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Hi everyone.



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So in this session we are going to learn something which is called victors.



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So if you remember the oboe section so in loops with color no problem.



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We implemented a glass and then all the glass was dynamic added glass.



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Now what is a.



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So that is basically inbuilt dynamic getting so whenever we have a feeling that I want to use that dynamic



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Eddie what we will use we will use vector because it does invert it is provided by C++ so it isn't built



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and we can directly use vectors.



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Now what does that mean to properties of vector.



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So just like the dynamic any glass that is exactly same as dynamic any glass or what will happen.



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So the first minute properties basically you do not have to give the size of the vector add friend you



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do not have to give.



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So if you are creating an eddy.



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How do we create an edit V right in a and then we will give the sides for example the scientist in mark



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for creating the vector.



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You do not have to give size.



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So that is the main benefit of the vector.



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There is no need to give size.



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And the second benefit of using vector or whatever it is is basically you can insert as much number



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of elements as you want.



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If we consider the array you cannot push.



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You cannot insert more than 10 elements.



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You cannot insert eleven elements inside this area but if you are using vector since the event is dynamic.



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So what will happen.



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We all know the property of that base.



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Basically it will double the size of entities food so for example if the event plays initially of size



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to if you will push the two elements.



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Basically the vector is field then what will happen that will double in size.



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So now the current size of the vector is basically four and you can insert the elements here.



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Similarly if this compute that base is filled then what will happen vector will again depoliticize it.



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So the size will become it if this factory is full then the size will become 16.



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So effectively keep doubling its size and basically you can insert as much number of elements as you



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want but with Daddy.



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Once you give the size you cannot insert more than 10 elements in this case but with vector you can



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insert as much number of elements as you want.



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And initially you do not have to give any size to career development to these other main properties



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why we use vector.



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So now let's see that in action.



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Let us see how we can use vector so first let us let's see how do we create a vector so I have to write



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the keyword vector so I will write vector Victor V.



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So is this right or wrong this is wrong why.



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Because vector is implemented using templates.



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So basically you have to give that in a type also.



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So I want to create that proof in integers so you have to write what you want to store in your vector.



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I want to store integer so you have to give in Peterhead now.



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As discussed many times there are two ways to create work.



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One is using the static a location and the other one is basically dynamic integration so that I see



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this index for creating vector dynamically so start VB vector pointer.



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This is new keyword then vector in tejas and this syntax.



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So this is actually dynamic and this one is actually static and we all know the difference between the



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starting and the dynamic dynamic means we have to dilute it ourself.



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It will not be deleted automatically we have to delete this vector but if we are looking static memory



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then what will happen so this vector will get deleted automatically.



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Once it will reach out of scope.



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Simple.



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So now let's see how we can insert the elements inside the vector.



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So for inserting the elements inside the vector we have a function pushback.



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So we start pushing back and let's say I want to insert certain so the suggest what is the use of pushback.



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So suppose this is my vector no pushback means as the name suggests I will push the element at the last.



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So Ben will be pushed at the last but since at this point of time my back is empty.



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So Ben will be pushed out different because the vector is empty but if we will push more elements for



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example you will push quanta and then you will push too hard.



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Then what will happen.



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So first they will be pushed.



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Then they will be pushed.



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So this will be the state of the vector 10 20 and then 30.



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Okay so let's see pushback function in action.



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So let us push more elements.



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So let us copy this and we do not have to worry about size.



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If the vector gets filled it size will become double to push as much a number of elements as you want



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so currently the size of my VAT is basically three disk containing three elements.



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Now how do accessed those elements.



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So we have square brackets.



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So just like in every we can access the elements of the vector using this credit brackets so let us



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copy this and let us access the elements



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visible we want and we do.



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So I am pushing these three elements and then I am printing these three elements simple so let's then



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our program so basically we are getting added at this line and what does that.



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Let's see the edit is basically V was not declared in the scope so if you want to use vector what we



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have to do we have to include a file hash include vector



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so after including this file hash include vector it will not give us error so let's say in our program



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and this is my output.



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So that's how Victor is working



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now.



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Can I change the elements once I've inserted those elements obviously.



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So what I will use I will use square brackets to change the elements.



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So suppose I want to change the element presented index 1 So what I will do V of 1 is let's say a hundred.



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So initially it was 20.



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Now I change its value 200.



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So let's see



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so then a hundred and then thirty initially this hundred it was 20 so this squared Beckett's just like



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it used to work in error.



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It would also work for vectors so since vector it also has square brackets.



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So what is the need of push back function.



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So what I want to say here is.



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So initially I have three elements inside the vector.



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Now let's push the fourth element so can I push the elements using this grid backwards just like we



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used to do in eddies.



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Can we do this too.



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Are these two lines valid.



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So let us try to understand so if you will think logically these two lines should not work because if



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these two lines worked then what is the use of pushback function.



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So that means these two lines will not work.



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So why do we need pushback function.



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What is the importance of push back function.



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So push back function inside the push back function what will do so there are checks implemented it



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will check what is the current size of the vector if the vector is getting filled.



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I have to double the size.



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So all these things are implemented in push back function.



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That's why for inserting the element we will always use push back function so if you will use this then



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what will happen.



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So the size of the vector will not increase.



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So size increase class size of the vector will not increase.



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So what are the elements.



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Do I have.



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So I have 10.



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Then I have 20 and then I have 30.



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Let's see what is happening here.



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So suppose initially let's say the size of the vector is basically 2 Let's say initially it is.



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Let us assume it is not 2 actually but let us assume the size of the initial vectors basically 2.



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So that means this.



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This line will create a vector of size 2.



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So what is happening.



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This is my back.



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Push then I can push 10 then I am pushing 20 so I can push 20 then in order to push 30 what will happen.



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The size then actively become double the size the vector is basically food.



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So you can push the 30 element and you can push one more element you can push when what element the



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size of the event base food.



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Now what I'm doing here.



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Change the second element so this is hundred now print okay.



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Now what they are doing you are pushing the fourth element so fourth element will be 1 0 0 2 but you



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are pushing the fifth element.



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So this is the fifth element and add this memory you are pushing 1 2 3 4.



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So basically my vector only has this much amount of memory so this memory does not belong to me.



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So this memory does not belongs to us.



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So basically you are pushing an element you are pushing an element at such a memory location and that



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number location does not belong to us.



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Okay so this is basically wrong and this is also wrong.



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So let us experiment with something.



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So let us experiment something so after pushing at fourth and fifth indexes let us push more elements



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so we don't push back let's say twenty three and let's do push



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okay.



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So in order to spend everything so



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okay.



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So if I will run my program which would be output so ideally what should be our output.



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So initially I have pushed 10 then 20 then 30.



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Then I change its value 200 then I am pushing so 1 0 0 2 and then I am pushing 1 2 3 4.



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And then we don't push back 23 and we don't push back to the default so if I will execute our code this



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should be my output.



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Ideally this should be an output Okay so please remember ten hundred thirty one 0 0 2 1 2 3 4 and then



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this one.



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So let's see where that output is correct or not.



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Let's delete this one



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so an order does allow program.



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So this is the output.



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So let's see whether our output was wrong or right.



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So as discussed.



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So ideally what should be our output.



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So what I pushed I pushed pen then Bush 20 then pushed 30 then change its value 200.



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Then I pushed using these square brackets 1 0 0 2 and 1 2 3 4 and then I used push back function to



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insert 2 3 4 and 23 and 2 3 4.



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So I leave my output should be this 1 but obviously this is our idle output is not coming out.



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So what is happening.



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So when you are using push malfunction to insert these elements what pushback function will do.



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It will push the element at the last.



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So for vector.



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This is the last 30 is the last because we didn't use push back function to insert these two elements



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we do not use push back function to insert these two elements somewhat push back function.



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This is the last index.



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So what will happen more should be output 10 then hundred then 30.



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So basically 23 will come here and then 2 3 4 so 2 3 4 and then basically so these two are removed and



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then what is happening so.



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So these two are basically lost then I'm accessing this memory location and then I'm accessing this



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memory location.



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So these telemetry location are basically garbage values and analogous these two garbage values are



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basically 0 1 0.



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So these two garbage values are basically zero and zero.



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It could have been anything but in our case they both had zero.



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So that's why you should not you should never use brackets to insert.



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You should always use pushback.



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Function



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now one more thing.



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So basically so basically how this function is able to access the sixth element and similarly the fifth



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element this is able to accept the sixth element because what it will do so it will say so underlying



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this is Amanda Lang Eddy.



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So it will go towards start address.



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It will take six jumps ahead and it will print what now it is present at this garbage location.



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So zero is present.



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That's why as you're always getting printed simple now I have a benefit of using these grid backwards



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and the alternate is basically add function the alternate is basically use of ad function.



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So let's see how we can use ad function and what is the difference between the ad function and the square



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brackets so one thing is quite clear here.



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This is very wrong so never use square brackets to insert elements because the size of the area will



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not increase the size of the vector will not increase the size will not become double.



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So this is wrong.



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Now let us use add function



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so obviously let's remove this one.



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Let's come on out everything so I want to use add function.



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So currently I have three elements and then two elements here.



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So the size of the vector is basically 5



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so c out v don't at add function really big index.



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So let us print what this present at the next full and let us also check what is present at index X



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so basically index 4 is a valid index the size of the vector is currently 5.



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So the last index is basically 4.



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So this is actually a valid index but index X is not valid index 6 is not a valid index.



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So if we will run our program let's see what will be our output



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so see what is the output so at the next food duty for this peasant.



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But at index 6 which is not a valid index you can see out of range the size of the vector is basically



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5 and you are trying to access the sixth element.



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So basically it is giving us.



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Edit It is giving us added.



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So what we can say so this ad function.



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It basically checks whether the index is valid or invalid.



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So basically we can see that using the add function is much much safer than using this square backward.



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So add is much much safer because it will check the index if you will.



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So if you will right we got at 6.



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It will give us error that the size of the vector is basically 5 and you and you cannot access index



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X but if we will use the square brackets 6 then what will happen.



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It will go just like an array.



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It will go to the starting position.



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It will take six jumps ahead and it will print out everything whatever it is present.



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So the output will be garbage now which one is better.



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So obviously this memory does not belong to us.



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So this is basically very bad.



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Obviously this is much better.



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So this is much safer using the add function is safer.



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Okay.



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So.



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So now let us use for loop to I told our director so how we can use for loop so let us comment out everything



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so let's use for loop so just like we used to isolate over the array.



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We can also add later with the vector so i equals zero i.e. less than we thought size now Vidor size.



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This is an build function or don't give me how many elements are present inside the vector.



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So currently 5 elements are present so the value of your size is 5.



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And here you can use vilify.



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And here you can use the square brackets and you can use at.



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So at this.



237

00:17:27,660 --> 00:17:30,700

So inside the for loop both you can use both.



238

00:17:30,700 --> 00:17:36,820

You can use Square Beckett and you can also use at the boathouse same way because index is always valued



239

00:17:37,390 --> 00:17:43,680

because of the for loop Woodward size will be 5 here inside the for loop it is safe to use board square



240

00:17:43,690 --> 00:17:50,520

brackets as well as the add function Mutassim so if you will run the program what will be our output.



241

00:17:50,660 --> 00:17:59,750

It will print the content of the vector so this is the content then handed today 23 and 24.



242

00:17:59,790 --> 00:18:02,380

So now we know how do I get over direct bed.



243

00:18:02,430 --> 00:18:07,200

So just like the pushback function I also have Bob back.



244

00:18:07,280 --> 00:18:11,090

So what Bob that function will do so v dot Bob back



245

00:18:15,600 --> 00:18:17,170

So bob back function what it will lose.



246

00:18:17,180 --> 00:18:19,260

So it will pop out the last element.



247

00:18:20,610 --> 00:18:25,890

So what is the use of pushback Pushback will insert the element at last.



248

00:18:26,060 --> 00:18:29,060

And Bob Beck will remove the last element.



249

00:18:29,090 --> 00:18:31,490

So basically this was the last element to form.



250

00:18:31,490 --> 00:18:36,750

So this element will be removed and the seismic activity become forward so four elements will be printed.



251

00:18:36,770 --> 00:18:37,220

Let's see



252

00:18:43,460 --> 00:18:48,140

so four elements are getting printed the size the vectors containing only four elements



253

00:18:53,070 --> 00:18:54,740

normally just kind out everything.



254

00:18:54,800 --> 00:18:56,870

And let's do some experiments



255

00:19:02,540 --> 00:19:10,350

so let us use a for loop to insert the elements inside the vector so let's say I want to push a hundred



256

00:19:10,350 --> 00:19:16,610

elements so when it does push hundred elements so we don't push back



257

00:19:19,770 --> 00:19:31,260

a plus one so I am pushing hundred elements and let us also print out our vector so I equals zero.



258

00:19:31,260 --> 00:19:35,840

I list and we out size and I plus plus



259

00:19:39,530 --> 00:19:40,520

C outreach if I



260

00:19:43,800 --> 00:19:49,070

so I am pushing hundred elements and then I am printing those hundred elements simple.



261

00:19:49,090 --> 00:19:49,700

Let's see



262

00:19:54,230 --> 00:19:58,760

so these are the elements inserted starting from when they landed.



263

00:19:58,760 --> 00:20:01,790

So yes civil code is working fine.



264

00:20:01,900 --> 00:20:03,700

Now let us see.



265

00:20:04,190 --> 00:20:06,730

Now let us also print the size.



266

00:20:06,820 --> 00:20:08,510

So when I am pushing the elements.



267

00:20:08,530 --> 00:20:10,690

Let us also print the size of the vector.



268

00:20:11,200 --> 00:20:14,320

So see out v dot size



269

00:20:17,710 --> 00:20:17,940

now.



270

00:20:17,950 --> 00:20:23,190

What should be our output what we what size will contain.



271

00:20:23,190 --> 00:20:27,150

So this size function foster it will contain one element.



272

00:20:27,150 --> 00:20:29,580

Then it will contain two then three then four.



273

00:20:29,580 --> 00:20:33,690

So basically this Vidor size it will increase linearly.



274

00:20:33,690 --> 00:20:37,780

And finally the size of the vector will become a hundred simple.



275

00:20:37,800 --> 00:20:42,990

There should be an output 1 200 the size the Vidor size.



276

00:20:43,030 --> 00:20:46,140

So the size of a vector will increase one by one.



277

00:20:46,150 --> 00:20:58,680

Simple so let's remove this thing and now we are liberating the size so let us also right size it what



278

00:20:58,680 --> 00:20:59,790

is the size of the vector



279

00:21:03,040 --> 00:21:07,530

and let's give and line also so let's see



280

00:21:11,160 --> 00:21:16,930

so you can see when you push it when you enter size will become one when you push the second element



281

00:21:16,930 --> 00:21:18,130

the size becomes too.



282

00:21:18,190 --> 00:21:20,440

When you push the third element the size becomes three.



283

00:21:20,470 --> 00:21:21,260

And so on.



284

00:21:21,430 --> 00:21:26,370

And finally when you will push the hundredth element the size of the vector will you become a hundred



285

00:21:26,710 --> 00:21:28,800

simple.



286

00:21:28,810 --> 00:21:34,550

Now we also have a function capacity so I have a function capacity.



287

00:21:34,550 --> 00:21:37,020

So what this capacity function will do.



288

00:21:37,160 --> 00:21:43,400

So it will give me what is the capacity what is the current capacity of my vector that will give me



289

00:21:43,430 --> 00:21:50,510

what is the current capacity of my vector and the difference between capacity and sizes size will give



290

00:21:50,510 --> 00:21:52,190

me how many elements at present.



291

00:21:52,190 --> 00:21:55,540

So for example let's say three elements are present.



292

00:21:55,550 --> 00:22:00,860

So size will give me that three elements that present me this capacity will give me how many elements



293

00:22:01,010 --> 00:22:04,670

you can insert inside the vector for example for example six.



294

00:22:04,670 --> 00:22:07,390

So the capacity will be six.



295

00:22:07,430 --> 00:22:12,980

Now let us print but we will print capacity and size and I'll deliver it should happen.



296

00:22:12,980 --> 00:22:18,460

So that capacity will become double capacity will become double as soon as the vector is full.



297

00:22:18,470 --> 00:22:19,580

So let's check it out



298

00:22:23,920 --> 00:22:25,750

so let's print the capacity



299

00:22:32,470 --> 00:22:35,730

b don't capacity.



300

00:22:35,830 --> 00:22:42,790

So this is also an build function function of basically vector and let's remove sides from here



301

00:22:50,850 --> 00:22:53,790

okay so let's Renamo code and let's see what will happen



302

00:23:01,000 --> 00:23:03,380

so let's try to understand what is happening here.



303

00:23:03,400 --> 00:23:08,350

So initially the capacities 0 and the size is also 0.



304

00:23:08,620 --> 00:23:10,750

Strange array of size 0.



305

00:23:10,750 --> 00:23:17,700

So basically this means that at starting and it didn't really exist and is basically null it doesn't



306

00:23:17,740 --> 00:23:24,700

exist when you push the first element the capacity becomes 1 and the size becomes 2 when you will push.



307

00:23:24,700 --> 00:23:31,000

So this is the first element the capacity is 1 in the size is when so many will push the second element



308

00:23:31,680 --> 00:23:33,280

that capacity will become place.



309

00:23:33,280 --> 00:23:39,850

So this is the capacity capacity becomes two and size is also 2 when you will push the third element.



310

00:23:39,860 --> 00:23:44,840

The capacity will become for the size will become double the capacity will become double the size the



311

00:23:44,840 --> 00:23:46,880

vector is basically for now.



312

00:23:46,880 --> 00:23:52,100

So you can push the fourth element and the capacity is still full but when you're pushing the fifth



313

00:23:52,100 --> 00:23:54,860

element the capacity becomes double.



314

00:23:54,860 --> 00:24:02,780

So the capacity it's basically the vector capacities it so you can safely push element six.



315

00:24:02,780 --> 00:24:07,730

You can push the element seven you can push element date but when you are trying to push the ninth element



316

00:24:07,970 --> 00:24:17,420

the capacity doubles so it will become sixteen so you can push that element girl 13 14 and so on.



317

00:24:17,420 --> 00:24:24,140

So finally when you will try to push the 17th element capacity will become 32 and so on.



318

00:24:24,140 --> 00:24:26,930

So it will keep going on.



319

00:24:26,960 --> 00:24:34,150

So finally let's see so finally the capacity is undaunted.



320

00:24:34,220 --> 00:24:38,180

And this is enough to hold a hundred elements.



321

00:24:38,180 --> 00:24:44,820

So capacity 128 is enough to hold these main number of elements okay.



322

00:24:44,840 --> 00:24:50,660

So we have seen how to create best and dynamically we know how to push elements.



323

00:24:50,660 --> 00:24:56,290

We know the capacity function we know the size function we know the public back function.



324

00:24:56,290 --> 00:25:02,440

So this when we dart ball back we know how to pop element we know how to push element we know how to



325

00:25:02,440 --> 00:25:06,960

change the elements we know how do I create all the director.



326

00:25:07,730 --> 00:25:12,500

So pretty much we know all the major functions of Director Okay.



327

00:25:12,520 --> 00:25:20,970

So when lasting how to create a vector of a given size for example I want to create a vector let's say



328

00:25:20,970 --> 00:25:25,500

of size 10 so you can give size here to giving size is optional.



329

00:25:25,500 --> 00:25:30,630

If you want to give the size you can if you don't want to give then don't give okay.



330

00:25:30,640 --> 00:25:37,210

So what if you want to initialize this vector so comma let's say I want to initialize this vector with



331

00:25:37,210 --> 00:25:43,860

the minus two so this victory has been initialized all the 10 values are basically minus two.



332

00:25:43,880 --> 00:25:44,740

You can also see.



333

00:25:45,620 --> 00:25:57,530

So let us print this vector OK let's change the name B to so equals zero list and we do a plus plus



334

00:25:59,530 --> 00:26:00,520

and see out



335

00:26:03,520 --> 00:26:03,970

symbol



336

00:26:08,120 --> 00:26:08,340

okay.



337

00:26:08,350 --> 00:26:10,000

So we do large sites



338

00:26:21,400 --> 00:26:27,100

so we'll see the vector has been interfaced or the 10 elements are minus two.



339

00:26:27,120 --> 00:26:28,910

So that's how you initialize of the



340

00:26:33,200 --> 00:26:35,210

so it is not necessary to initialize the vector.



341

00:26:35,660 --> 00:26:43,050

So if you write like this vector of indigenous v V3 and you can only give size.



342

00:26:43,130 --> 00:26:44,480

So this is also correct.



343

00:26:45,140 --> 00:26:48,630

Okay so can we start the vector.



344

00:26:48,740 --> 00:26:50,950

So yes we can start direct it.



345

00:26:51,110 --> 00:26:52,760

I haven't ruled functions out.



346

00:26:52,910 --> 00:26:53,710

So what do we do.



347

00:26:54,970 --> 00:27:00,280

I will write like this for example I want to sort vector we to suicide we do not begin



348

00:27:03,310 --> 00:27:08,970

we do dart and so just like Eddie we have to give the starting in the end items.



349

00:27:09,190 --> 00:27:16,590

So sort of you got begin and we do not end and my vector will become sorted my vector will be sorted.



350

00:27:16,680 --> 00:27:23,790

Okay so we know how to initialize we know how to give how to create a vector of a given size we know



351

00:27:23,790 --> 00:27:29,490

how to sort of vector so pretty much we know all the functions all the major functions of the vector



352

00:27:30,770 --> 00:27:31,000

okay.



353

00:27:31,010 --> 00:27:33,480

So I think this is enough.



354

00:27:33,480 --> 00:27:35,420

I will show you in the next one by.