CODEWITHSUNDEEP
objective-ccconstantsswitch-statement
dan983
dan983

Reputation: 494

Switch Statement constant issue

- (void)change:(int)a {
   int number = a;
   int max = 10;

   switch(max) {
     case number:
       //Do something
       break;

       //.... more cases
   }
}

This is just a small example of the issue I can't seem to solve. I have looked at similar posts and answers usually include using constants via a #define or enum, however these are great when you have a constant that is fixed but if the value is passed through as a parameter how could I do this? if it's possible at all. Any advice would be appreciated.

Upvotes: 0

Views: 408

Answers (2)

Richard Chambers
Richard Chambers

Reputation: 17623

A switch statement is used to test the value of a variable against a list of constant expressions. The difference between a switch with its various case statements and a series of if/elseif statements for the same comparisons is more of a syntax difference than a logic difference.

However the if/elseif statements are more flexible since they do not require constant expressions and you can also use more complex logical expressions in the if/elseif as well.

For instance:

switch (iValue) {
    case 1:
        break;
    case 4:
        break;
    default:
        break;
}

has the same meaning as this series of if/elseif statements:

if (iValue == 1) {
} else if (iValue == 4) {
} else {
}

Most of the time a compiler will generate a series of if/elseif code when it is generating the code for a switch statement. So the actual code generated by the compiler for an if/elseif statement series is similar to the code generated for a switch statement.

Upvotes: 0

Jacob Relkin
Jacob Relkin

Reputation: 163288

In a nutshell, case statements can only operate on constant expressions, so if you need more dynamic conditionals, you will have to use if statements.

Upvotes: 3

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