计算器程序问题

Question

I am trying to work out why this program is not working. It is supposed to perform operations like

5 * 4 = 20 4 + 2 * 8 = 20 6/3 - 2 = 0.

However, things are not working.

Instructions are:

Write a C program called calculate that performs simple arithmetic operations. The program takes 3 or 5 arguments from the command line.

I am not sure what to do now.

int calc(int x, char op, int y) {
    if (op == '+') {
        return (x+y);
    }
    if (op == '-') {
        return (x-y);
    }
    if (op == 't') {
        return (x*y);
    }
    if (op == '/') {
        return (x/y);
    }
}

int main(int argc, char *argv[]) {
    int a,b,c,result,doOp;
    char op1, op2;

    if (argc == 4 || argc == 6) {
        a = atoi(argv[1]);
        b = atoi(argv[3]);
        op1 = *argv[2];
    } else {
        printf("Wrong number of arguments!");
        return 0;
    }

    if (argc == 6) {
        c = atoi(argv[5]);
        op2 = *argv[4];

        if ((op1 == '+' || op1 == '-') && (op2 == '/' || op2 == 't')) {
            result = calc(a, op1, calc(b, op2, c));
            printf("%d", result);
        }

        if ((op2 == '+' || op2 == '-') && (op1 == '/' || op1 == 't')) {
             result = calc((calc(a, op1, b)), op2, c);
             printf("%d", result);
        } else {
             result = calc((calc(a, op1, b)), op2, c);
             printf("%d", result);
        }
    }

    if (argc == 4) {
        result = calc(a, op1, b);
        printf("%d", result);
    }
    return 0;
}

Answer 1

Here you go Alireza. The problems are several, but the main one was the missing "else" in your check to see which calculator sequencing to use.

int calc(int x, char op, int y) {

    if (op == '+') {
        return (x+y);
    }
    if (op == '-') {

        return (x-y);
    }
    if (op == 't') {

        return (x*y);
    }
    if (op == '/') {
        return (x/y);
    }

    printf("Unknown operator!"); // added error check
}

int main(int argc, char *argv[]) {

    int a,b,c,result,doOp;
    char op1, op2;

    if (argc == 4 || argc == 6) {

        a = atoi(argv[1]);
        b = atoi(argv[3]);
        op1 = *argv[2];

    } else {
        printf("Wrong number of arguments!");
        return 0;
    }

    if (argc == 6) {
        c = atoi(argv[5]);
        op2 = *argv[4];

        if ((op1 == '+' || op1 == '-') && (op2 == '/' || op2 == 't')) {

            result = calc(a, op1, calc(b, op2, c));
            printf("%d", result);
        }
        // added else if
        else if ((op2 == '+' || op2 == '-') && (op1 == '/' || op1 == 't')) {

            result = calc((calc(a, op1, b)), op2, c);
            printf("%d", result);
        }
        else {
            result = calc((calc(a, op1, b)), op2, c);
            printf("%d", result);
        }
    }

    if (argc == 4) {

        result = calc(a, op1, b);
        printf("%d", result);
    }

    return 0;
}