reverse.cpp

/* Problem 1.2: Implement a function void reverse(char* str)
 * in C or C++, which reverses a null-terminated string.
 * @author: Rafayel Mkrtchyan
 * @date:   9/14/2015
 */
 
#include <iostream>

/* This function takes an iterative approach to problem
 * using an O(n) speed.
 */
void reverse_string(char* str) {
    char* sameStr = str;
    char temporary;
    if (str) {
        while(*sameStr) {
            ++sameStr;
        }
        --sameStr;
        while (str < sameStr) {
            temporary = *str;
            *str++ = *sameStr;
            *sameStr-- = temporary;
        }
    }
}

int main() {
    std::string str = "Berkeley";
    char* writable = new char[str.size() + 1];
    std::copy(str.begin(), str.end(), writable);
    writable[str.size()] = '\0';
    reverse_string(writable);
    std::cout << writable << std::endl;
    delete[] writable;
    return 0;
}