Question

write a c++ program to reverse the string using pointers? please help

Answer 1

do you have a char buffer for the result?

Answer 2

do you have to use char arrays or std::string?

Answer 3

OK, here is an in-place solution:

#include <iostream>

void reverse(char* s)
{
const int n = strlen(s);
for (int i = 0; i < n / 2; ++i)
{
char c = s[i];
s[i] = s[n - 1 - i];
s[n - 1 - i] = c;
}
}

int main(int argc, char *argv[])
{
char s[] = "hello, world";
reverse(s);
std::cout << s << std::endl;
return 0;
}

Answer 4

#include "stdafx.h"

const int strLen=6;
char szStart[strLen] = "Hello";
char szEnd[strLen] = "";

int _tmain(int argc, _TCHAR* argv[])
{
//declare the pointers
char* pszStart = szStart;
char* pszEnd = szEnd;

//make the destination pointer point to the end of the string,
//-2 because of the end of string char. Without it we would copy the
//string exactly reversed and the end of strign would be the first char
//and we would see nothing :D
pszEnd += strLen-2;

//1) dereference the pointers
//2) assign source char to destination char
//3) decrease the destination pointer and,
//4) increase the source pointer
//5) lastly check we are not assigning the end of string char and if so quit while
//check we are not at the end of the string
while ((*pszEnd-- = *pszStart++) != NULL);

return 0;
}

Answer 5

Of course this is really a c style app. Todo a c++ version of this really misses the point of c++. It is definitely overkill to use classes for tis type of problem but I suppose it cold be done. Char class, and a string reverser class.
c++ is mainly used in larger systems to encapsulate complexity and simplify interfaces between modules.