title=VARIABLE cannot appear in a constant-expression

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Causes[edit]

Using a variable for a switch case statement[edit]

While a switch statement often use a variable for an argument, their case statements cannot use variables as arguments.

int foo = 7;
int bar = 4;
switch(foo) {
   case bar: 
      cout << "This is case 0" << endl; 
}

Solution: Make the case statement's argument a constant

int foo = 7;
const int bar = 4;
switch(foo) {
   case bar: 
      cout << "This is case 0" << endl; 
}

Notes[edit]

  • Message found in GCC version 4.5.1
  • In GCC version 3.2.3, reported as: case label does not reduce to an integer constant
  • This message can come up about strings- however, you cannot make a string constant