如何从C中的命令行读取*

Question

我会直截了当地说.这是我的代码,我想从命令行参数中读取'*'字符,但它无法正常工作.我希望你能解释一下我做错了什么.

#include <stdio.h>
#include <stdlib.h>

int sum(int, int);
int rest(int, int);
int division(int, int);
int mult(int, int);
int module(int, int);

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

    char operator;
    int number1;
    int number2;
    int result;

    if(argc != 4){
        printf("Wrong parameter quantity (%d of 3 needed)\n", argc-1);
        return -1;
    }

    number1 = atoi(argv[1]);
    operator = *argv[2];
    number2 = atoi(argv[3]);

    switch(operator){
        case '+':
                result = sum(number1, number2);
                printf("%d %c %d = %d\n", number1, operator, number2, result);
                break;
        case '-':
                result = rest(number1, number2);
                printf("%d %c %d = %d\n", number1, operator, number2, result);
                break;
        case '/':
                result = division(number1, number2);
                printf("%d %c %d = %d\n", number1, operator, number2, result);
                break;
        case '*':
                result = mult(number1, number2);
                printf("%d %c %d = %d\n", number1, operator, number2, result);
                break;
        case '%':
                result = module(number1, number2);
                printf("%d %c %d = %d\n", number1, operator, number2, result);
                break;
        default:
                printf("Error. Wrong operator inserted (%d, %c)\n", operator, operator);
                return -2;
    }

    return 0;
}

int sum(number1, number2){
    return number1 + number2;
}

int rest(number1, number2){
    return number1 - number2;
}

int division(number1, number2){
    return number1 / number2;
}

int mult(number1, number2){
    return number1 * number2;
}

int module(number1, number2){
    return number1 % number2;
}

我知道我的错误是这行,operator = *argv[2];但我不知道当'*'字符通过命令行参数传递时会发生什么.对于所有其他符号(+, - ,/,%)一切正常.我在Ubuntu中对此进行编码,并使用gcc在命令行中进行编译.

Answer 1

问题不在你的程序中.这就是你如何称呼它.

UNIX/Linux shell自动*在命令行上扩展到当前目录中的所有文件.为了防止这种情况,您需要引用它.

所以不要这样做

./prog 3 * 4

做这个:

./prod 3 "*" 4

或这个:

./prod 3 \* 4