c++ replace what with with on char array(string) - c++

Question

I have the task to write a function char * stringReplace(const char * str, const char * what, const char * with) which replaces "what" with "with" on a new string with the correct length. So Inside the function I created dynamic array, which the function returns. But my question is how can I delete it after, as If i try to delete it in the main function, after i use it, it says it's undefined. Aren't dynamic arrays without a scope or I'm wrong?
Here's my code:
#include <iostream>
#include <string.h>
using namespace std;
bool areTheSame(const char * str, const char * what, unsigned p)
{
return areEqual;
}
unsigned howManyTimes(const char * str, const char * what)
{
}
char * stringReplace(const char * str, const char * what, const char * with)
{
}
int main()
{
char str[1000];
char what[1000];
char with[1000];
cout << "Enter your string\n";
cin.getline(str, 1000);
cout << "\nEnter \"what\" you want to replace\n";
cin.getline(what, 1000);
if (strlen(str) < strlen(what))
{
cout << "\"What\" contains more characters than the string!\n";
return 0;
}
cout << "\nEnter with what you want to replace it\n";
cin.getline(with, 1000);
cout << "\nYour string with replaced words looks like\n";
cout << stringReplace(str, what, with) << endl;
return 0;
}
P.S I deleted parts of the code as I found the answer I wanted and there is still time for the task, and I'm not sure I'm allowed to post my code publicly

Answer 1

You have to delete it in order to avoid memory leak. You can do something like this:
int main()
{
char str[1000];
char what[1000];
char with[1000];
char *replaced;
cout << "Enter your string\n";
cin.getline(str, 1000);
cout << "\nEnter \"what\" you want to replace\n";
cin.getline(what, 1000);
if (strlen(str) < strlen(what))
{
cout << "\"What\" contains more characters than the string!\n";
return 0;
}
cout << "\nEnter with what you want to replace it\n";
cin.getline(with, 1000);
cout << "\nYour string with replaced words looks like\n";
replaced = stringReplace(str, what, with);
cout << replaced << endl;
delete [] replaced;
return 0;
}
However note that this isn't the best pratice to split allocation/deallocation responsibility.