Reversing a string.

string_reverse.c

# include<stdio.h>
# include<string.h>

# define SWAP(a, b) {char tmp; tmp=a; a=b; b=tmp;}

int main(){
    char str[80];
    int len, i;

    scanf("%[^\n]*c", str);
    len = strlen(str);

    for (int i=0; i<(len/2); i++){
        SWAP(str[i], str[len-(i+1)]);
//        printf("Pass %d: %s\n", i+1, str);
    }

    printf("%s\n", str);

    return 0;
}