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 
#include 
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;
}