One of the problems in K. N. King’s C Programming: A Modern Approach asks the reader to write a function that takes a string and, using two pointers, reverses it.

I spent about two hours fighting against this relatively simple problem. Why? Because the part of my mind that understands with pointer arithmetic wasn’t engaged. The solution is relatively simple:

// This program will reverse a string.
#include <stdio.h>

#include <strings.h>
int main(void) {
	char str[] = "abcdefg";

	char* pFirst = str;

	char* pLast = pFirst + strlen(str) - 1;

	char temp;
	while (pLast > pFirst) {

		temp = *pFirst;

		*pFirst++ = *pLast;

		*pLast-- = temp;

	}
	puts(str);
	return 0;

}