我可以在C ++中的if语句中使用switch case的大小写

Question

#include <iostream>
using namespace std;

int main() {
    int a=2,b=2;
    switch(a){
    case 1:
        cout<<"A"<<endl;
        if(b==5){
            case 2:
                cout<<"A"<<endl;
        }
    case 3:
        cout<<"A"<<endl;
    }
    return 0;
}

not able to understand how this code outputs 2 "A"s,how can you put if statement outside of case

Answer 1

You don't have a break anywhere, so when case 2 is hit, it falls through to case 3 and prints the second A.

If you used different output in each case that would have been a bit more obvious.

And yes the grammar lets you put the case inside an if, the same as it allowed duff's device to compile.

Answer 2

它输出2'A 'A'因为你没有提供break语句。