C string reversal

str_reverse.c

int main()
{
    char s[20], r[20];
    int begin, end, count = 0;

    printf("Input a string\n");
    scanf("%s", s);

    // Calculating string length
    while (s[count] != '\0')
        count++;

    end = count - 1;

    for (begin = 0; begin < count; begin++) {
        r[begin] = s[end];
        end--;
    }

    r[begin] = '\0';

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

    return 0;
}