如何使用 C 将具有 2 个变量的 IF 语句转换为 switch 函数? [英] How do I transform an IF statement with 2 variables onto a switch function using C?

问题描述

我有一个 IF 语句，我想将它转换为一个 Switch 语句......但它有 2 个变量！是否可以在 C 上完成?

I have an IF-statement that I want to transform into a Switch-statement... But it has 2 variables! Is it possible to do it on C?

这是一个石头、纸、剪刀的游戏:

It is a rock, paper, scissors game:

(R代表石头，P代表纸，S代表剪刀)

(R for rock, P for Paper, S for Scissors)

     char play1, play2;

     printf("
Player 1 - Enter your Play: ");
     scanf ("%c", &play1);
     printf("
Player 2 - Enter your Play: ");
     scanf (" %c", &play2); 


     if (play1 == 'R' && play2 == 'P') {
       printf ("Paper wins!"); }
      else if (play1 == 'R' && play2 == 'S') {
        printf ("Rock wins!");}
      else if (play1 == 'R' && play2 == 'R) {
        printf ("Draw!");}

而且我必须为其他选项这样做，所以最好使用 switch！

and I have to do this for the others options, so it would be better to use switch!

推荐答案

#include <stdio.h>

#define SWITCH(a, b) char _a = a; char _b = b; if (0)
#define CASE(a, b) } else if ((a == _a) && (b == _b)) {

int main(void)
{
    char play1, play2;

    printf("
Player 1 - Enter your Play:");
    scanf ("%c", &play1);
    getchar();
    printf("
Player 2 - Enter your Play:");
    scanf ("%c", &play2);
    getchar();

    SWITCH(play1, play2) {
        CASE('R','P') printf ("Paper wins!");
        CASE('R','S') printf ("Rock wins!");
        CASE('R','R') printf ("Draw!");
    }
    return 0;
}

这是个笑话:P

:"的大小写支持

#define PASTE(a, b) a##b
#define LABEL(a, b) PASTE(a, b)
#define SWITCH(a, b) char _a = a; char _b = b; if (0)
#define CASE(a, b) } else if ((a == _a) && (b == _b)) { LABEL(LBL, __LINE__)

但不适用于:

CASE('R','R'): printf ("Draw a!"); CASE('S','R'): printf ("Draw!");

两个case在同一行

解决方法:

#define SWITCH(a, b) char _a = a; char _b = b; if (0)
#define CASE(a, b) } else if ((a == _a) && (b == _b)) {switch(1) case 1

希望没有人使用它:)

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