How do you reverse a string in place in C or C++?

Question

How do you reverse a string in C or C++ without requiring a separate buffer to hold the reversed string?

Answer 1

Share my code. As a C++ learner, as an option to use swap(), I am humbly asking for comments.

void reverse(char* str) {
    int length = strlen(str);
    char* str_head = str;
    char* str_tail = &str[length-1];
    while (str_head < str_tail) 
        swap(*str_head++, *str_tail--);
}