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Tux9000
Asked: 2020-06-10 16:09:23 +0800 CST 2020-06-10 16:09:23 +0800 CST

Can an OR or AND be used with a Switch?

  • 772

Could I do something like this with C/C++?

    var a = 8;
        
    switch(a){ 
     case a>=12:
      console.log("a");
     break;
        
     case a>1 || a<6:
      console.log("aa");
     break;
        
     default:
      console.log("aaa");
     break;
    }

I tried something similar in C/C++ but I get an error when compiling, something like:

the value of 'a' cannot be used in a constant expression note: 'int a' is not a const

The code I tried was something like:

int miVar;
char letra;

cout<<"Digite el valor:"<<endl;
cin>>miVar;


switch(miVar){

    case miVar<=30000:
    letra = 'A';
    break;

    case (miVar>30000 & miVar<=60000):
    letra = 'B';
    break;

    default:
    letra = 'C';
    break;
}
c++

1 Answers

  1. Best Answer

    You can't, you have to use a constant value (defined at compile time).

    The error it shows you is because it tries to interpret the expression you pass to it as a constant and it can't.

    Also, even if a were a constant, what it would do to you would be to evaluate the expression on compilation and give you a boolean value, and that fixed value would be what it would compare. Don't use a curve because in C/C++ booleans are actually integer : the result would be equivalent to case 0 (if the expression evaluated to false ) or case [number other than 0] if the expression evaluated to true .

    The only thing similar to an or would be to put the values ​​in several cases and not put a break between them .

    switch (a) {
case 0: break;
case 1:
case 2:
case 3: // a esta línea se llega si a es 1, 2 ó 3, pero no 0
    • 3