How to dynamically increase the array size?

Question

I\'ve been trying to make a program that adds 2 arrays of different size. But I would like to know to to dynamically increase the array size capacity? Ex: array[4] then upgrade

Answer 1

#include <stdio.h>
#include <stdlib.h>
int main()
{
int *p,*q;
int i;
p=(int *)malloc(5*sizeof(int));
p[0]=3;p[1]=5;p[2]=7;p[3]=9;p[4]=11;
q=(int *)malloc(10*sizeof(int));
for(i=0;i<5;i++)
q[i]=p[i];
free(p);
p=q;
q=NULL;
for(i=0;i<5;i++)
printf("%d \n",p[i]);
return 0;
}

Answer 2

   int* newArr = new int[new_size];
   std::copy(oldArr, oldArr + std::min(old_size, new_size), newArr);
   delete[] oldArr;
   oldArr = newArr;

Answer 3

You can't change the size of the array, but you don't need to. You can just allocate a new array that's larger, copy the values you want to keep, delete the original array, and change the member variable to point to the new array.

1. Allocate a new[] array and store it in a temporary pointer.

2. Copy over the previous values that you want to keep.

3. Delete[] the old array.

4. Change the member variables, ptr and size to point to the new array and hold the new size.