Question

我做了三个不同的功能。我正在尝试让用户选择要操作的功能。为此，我正在尝试使用switch语句。用户输入两个数字，然后选择要对这些数字进行操作的功能。这是我的当前代码，无法正常工作。函数MultbyTwo，isFirstBigger和addVat。

#include <stdio.h>

int multbyTwo (int a){
    return a*2;
}

int isFirstBigger (int a, int b){
    if (a<b){
    printf("1");
    }
    else {
    printf("0");
    }
}

float addVat(float a, float 20){
    return (a/100)*20;
}

int main(){


    int a,b;
    int choice;
    printf("Which Function [0:multbyTwo,1:isFirstBigger,2:addVat]:");
    scanf("%d",&choice);

    printf("a:\n");
    scanf("%f",&a);
    printf("b:\n");
    scanf("%f",&b);

    switch (choice){
        case 0: printf(multbyTwo(a));
            break;
        case 1: printf(isFirstBigger(a,b));
            break;
        case 2: printf(addVat(a));
            break;
    }

}

Answer 1

除了我在评论中提到的问题之外，您的printf调用中还缺少格式字符串。这是您的代码的有效版本，无论我更改了什么地方，都添加了“ ///”注释：

#include <stdio.h>

int multbyTwo(int a) {
    return a * 2;
}

int isFirstBigger(int a, int b) {
    if (a < b) {
    //  printf("%s", "1"); /// You print the result in main!
        return 1; /// You MUST return a value!
    }
    else {
    //  printf("%s", "0"); /// You print the result in main!
        return 0; /// You MUST return a value!
    }
}

float addVat(float a, float vat) { /// Change here to allow a value of vat to be passed
    return (a / 100) * vat;        /// ... and here to use the passed value (not fixed)
}

int main() {
    int a, b;
    int choice;
    printf("Which Function [0:multbyTwo,1:isFirstBigger,2:addVat]:");
    scanf("%d", &choice);

    printf("a:\n");
    scanf("%d", &a); /// Use %d for integers - %f is for float types
    printf("b:\n");
    scanf("%d", &b); /// Use %d for integers - %f is for float types

    switch (choice) { /// each call to printf MUST have the format string as the first argument...
        case 0: printf("%d", multbyTwo(a));///
            break;
        case 1: printf("%d", isFirstBigger(a, b));///
            break;
        case 2: printf("%f", addVat((float)a, 20));/// Now, we must pass the value of "vat" to use in "addVat()"
            break;
    }
    return 0; /// It's good practice to always have this explicit "return 0" in main!
}

希望对您有所帮助！（但是我不得不说，还有很多改进的空间。）

随时要求进一步的澄清和/或解释。

我正在尝试制作一个可以运行不同功能的程序，具体取决于用户在C语言中的选择

1 个答案: