Can I declare variables inside an Objective-C switch statement?
Objective CSwitch StatementObjective C Problem Overview
I think I'm going blind, because I can't figure out where the syntax error is in this code:
if( cell == nil ) {
titledCell = [ [ [ TitledCell alloc ] initWithFrame:CGRectZero
reuseIdentifier:CellIdentifier ] autorelease
];
switch( cellNumber ) {
case 1:
NSString *viewDataKey = @"Name";
etc...
When I try to compile it, I'm getting an Error: syntax error before '*' token on the last line.
Sorry for such a basic question, but what am I missing?
Objective C Solutions
Solution 1 - Objective C
I don't have a suitable Objective-C compiler on hand, but as long as the C constructs are identical:
switch { … }
gives you one block-level scope, not one for each case
. Declaring a variable anywhere other than the beginning of the scope is illegal, and inside a switch
is especially dangerous because its initialization may be jumped over.
Do either of the following resolve the issue?
NSString *viewDataKey;
switch (cellNumber) {
case 1:
viewDataKey = @"Name";
…
}
switch (cellNumber) {
case 1: {
NSString *viewDataKey = @"Name";
…
}
…
}
Solution 2 - Objective C
You can't declare a variable at the beginning of a case statement. Make a test case that just consists of that and you'll get the same error.
It doesn't have to do with variables being declared in the middle of a block — even adopting a standard that allows that won't make GCC accept a declaration at the beginning of a case statement. It appears that GCC views the case label as part of the line and thus won't allow a declaration there.
A simple workaround is just to put a semicolon at the beginning of the case so the declaration is not at the start.
Solution 3 - Objective C
In C you only can declare variables at the begining of a block before any non-declare statements.
{
/* you can declare variables here */
/* block statements */
/* You can't declare variables here */
}
In C++ you can declare variables any where you need them.
Solution 4 - Objective C
You can create a variable within a switch statement but you will have to create it within a block so that the scope of that variable is defined.
Example:
switch(number){
case 1:
{
// Create object here
// object is defined only for the scope of this block
}
break;
case 2:
{
// etc.
}
break;
default:
break;
}
Solution 5 - Objective C
Might it not be valid to declare a variable within a switch block?
Solution 6 - Objective C
How to solve the warning:
1.Insert one ;
in the first line of your case block
2.Put codes inside braces