Question

This part alone is crashing my program. Why is that? This is to add a ‘u’ after each ‘p’ in the string.

for(int i=0;i<s.size();i++)
{
    if((s[i]=='p'))
    {
        s.insert(i,1,'u');
    }
}
cout<<"after adding u after each p: "<<s;

Answer 1

(You’ve written ‘u’ instead of ‘h’ in your code.)

Let’s assume you have the string that is just “p”. So s[0] == ‘p’. Now you insert ‘h’ at 0 so the string is now “hp” (the h is before the p, not after it as you intended). In the next iteration i is 1 and there is a p (it just moved there) so another h will be inserted. This goes on until you run out of memory.

Try:

s.insert(i + 1, 1, 'h');