tring function

hello
can anyone write me a function for string reversal
without using string functions and without using a temporary
character array
to store the reversed string

This code will only work in release mode if you're using VC++6. I don't know why, but VC++6 probably protects memory writes to make debugging easier or something. Anyway it works in release mode.

Code:

---

#include <iostream>

char *revstr(char *str)
{
        int length = strlen(str)-1;
        char *pstrstart = str;
        char *pstrend = str + length;

        while((pstrend - pstrstart) > 0)
        {
                //swap characters
                *pstrstart = *pstrstart ^ *pstrend;
                *pstrend  = *pstrstart ^ *pstrend;
                *pstrstart = *pstrstart ^ *pstrend;
                pstrstart++;
                pstrend--;
        }

        return str;
}


int main()
{
        char *str = "abcde";
        std::cout << "revstr(\"abcde\") => " << revstr(str) << std::endl;
       
        return 0;
}

---

Oops, just realised I had a string function in there (strlen).

Here's the alternative:

Code:

---

#include <iostream>

char *revstr(char *str)
{
        char *pstrstart = str;
        char *pstrend = str;
        while(*(pstrend+1) != '\0')
                pstrend++;

        int length = pstrend - pstrstart-1;
       
        while((pstrend - pstrstart) > 0)
        {
                //swap characters
                *pstrstart = *pstrstart ^ *pstrend;
                *pstrend  = *pstrstart ^ *pstrend;
                *pstrstart = *pstrstart ^ *pstrend;
                pstrstart++;
                pstrend--;
        }

        return str;
}


int main()
{
        char *str = "abcde";
        std::cout << "revstr(\"abcde\") => " << revstr(str) << std::endl;
       
        return 0;
}

---

thank you HarryW

it is fine
:p