替代 C 中的许多 case switch 语句 [英] Alternative to many case switch statement in C

问题描述

我有一个 8 位字节，代表 8 个物理交换机的状态.我需要为每次打开和关闭的开关排列做一些不同的事情.我的第一个想法是写一个 256 case switch 语句，但很快打字就变得乏味了.

I have a 8 bit byte that represents the states of 8 physical switches. I need to do something different for each permutation of switches being on and off. My first idea was to write a 256 case switch statement, but it quickly became tedious to type.

有没有更好的方法来做到这一点?

Is there a better way to do this?

我应该对功能更清楚一些.我有 8 个按钮，每个按钮都做一件事.我需要能够检测是否同时按下了多个开关，以便我可以同时运行这两个功能.

I should have been a bit clearer on the functions. I have 8 buttons that each do one thing. I need to be able to detect if multiple switches are pressed at once so I can run both functions at the same time.

推荐答案

您可以使用函数指针数组.小心用正值索引它 - char 可能会被签名.这是否比使用 switch 语句更乏味是有争议的 - 但执行肯定会更快.

You can use an array of function pointers. Be careful to index it by a positive value - a char might be signed. Whether this is any more tedious than using a switch statement is arguable - but execution will certainly be quicker.

#include <stdio.h>

// prototypes
int func00(void);
int func01(void);
...
int funcFF(void);

// array of function pointers
int (*funcarry[256])(void) = {
    func00, func01, ..., funcFF
};

// call one function
int main(void){
    unsigned char switchstate = 0x01;
    int res = (*funcarry[switchstate])();
    printf ("Function returned %02X\n", res);
    return 0;
}

// the functions
int func00(void) {
    return 0x00;
}
int func01(void) {
    return 0x01;
}
...
int funcFF(void) {
    return 0xFF;
}

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