Compile Error with: switch, "expected expression before"

Cut to the chase I have recreated my problem as it is fairly self explanatory.

this complies without error:

switch (n) {
case 1:
NSLog(@"");
NSString *aStr;
break;
default:
break;
}

this compiles with error and it's only missing the NSLog():

switch (n) {
case 1:
NSString *aStr;
break;
default:
break;
}

it throws an error at compile "Expected expression before 'NSString'"

Am I missing something here?

52962 次浏览

小开

最佳答案

In normal C you'd have to enclose this in brackets in both cases. I suspect this may fix your problem:

case 1:
{
NSLog(@"");
NSString *aStr;
break;
}

See this SO question for more info.

Another way to get around this problem is to put a statement between the case label and the first declaration as you've done in your working example above. See the comments and Quinn Taylor's answer for more info.

小开

You can't declare a variable as the first statement in a case without brackets, and in many other contexts in C-based languages. See Declaring variables inside a switch statement for details.

小开

case 0: {
Loading my nib file;
break;
}
case 1: {
Loading another nib file;
break;
}
Note that if you don't have an assignment (x = y) right after the case it won't be a problem. For example: