Given a balanced expression that can contain opening and closing parenthesis, check if the expression contains any duplicate parenthesis or not.

is_duplicated.c

// Given a balanced expression that can contain opening and closing parenthesis, 
// check if the expression contains any duplicate parenthesis or not.
unsigned is_duplicated(char str[], stck * st) {
    int index = 0;
    char ch;
    while (str[index] != '\0') {
        ch = str[index]; 
        if (ch != ')') 
            push(ch, st);
        else {
            if (get_peek(*st) == '(')
                return 1;
            while (get_peek(*st) != '(')
                pop(st);
        }
        pop(st);
        index++;
    }
    return 0;
}