如何简化c ++中的多个if-else-if语句 [英] How to simplify multiple if-else-if statements in c++

问题描述

假设我有四个函数用于四种情况：

Suppose I have four functions for four cases:

void ac() {
 //do something
}
void ad() {
 //do something
}
void bc() {
 //do something
}
void bd() {
 //do something
}

void f(bool a, bool b, bool c, bool d) {
    if(a and c) {
        ac();
    }
    else if(a and d) {
        ad();
    }
    else if(b and c) {
        bc();
    }
    else if(b and d){
        bd();
    }
    else {
            throw 1;
    }
}

对于2乘2的情况来说很简单，在更复杂的情况下，
这可以得到非常乏味。是否有办法简化此操作？

For the 2 by 2 situation it's quite simple, but in more complex situations, this can get very tedious. Is there a way to simplify this?

推荐答案

#define A 0x1
#define B 0x2
#define C 0x4
#define D 0x8

void f(bool a, bool b, bool c, bool d) {
    int mask = 0;
    if( a ) mask |= A;
    if( b ) mask |= B;
    if( c ) mask |= C;
    if( d ) mask |= D;
    // Alternative is to use mask as a subscript in an array of function pointers.
    switch( mask ) {
    case A|C: ac(); break;
    case A|D: ad(); break;
    case B|C: bc(); break;
    default: bd(); break;
    }
}

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