Equal strings not equal? [duplicate]

问题

Possible Duplicate:
Understanding NSString comparison in Objective-C

I'v encountered strange things in objective-c, I'm trying to compare cell.label with elements title which is string. to identify whever it is a cell I am looking for.

NSLog(@"%@", cell.textLabel.text);
NSLog(@"%@", [_dropDownSelection1.elements[1] title]);
if(cell.textLabel.text == [_dropDownSelection1.elements[1] title]){
    NSLog(@"Positive");
}
else{
    NSLog(@"Negative");
}

NSLog prints that the text in both is exactly the same, but still i always end up with negative... Why is that?

回答1:

You should use [cell.textLabel.text isEqualToString:[_dropDownSelection1.elements[1] title]] to compare the strings.

回答2:

You are comparing pointers with one another, not the strings.

Use IsEqual instead.

回答3:

You can't compare them like that.

See the section Identifying and comparing strings on the Objective-C docs.

回答4:

Here is the code which worked for me! I don't know why but, without initializing variables i couldn't get it work, even using isEqualToString as provided above.

NSLog(@"CELL:%@", cell.textLabel.text);
NSLog(@"ELEM:%@", [_dropDownSelection1.elements[1] title]);
NSString *labl = cell.textLabel.text;
NSString *tit = [_dropDownSelection1.elements[1] title];

if([labl isEqualToString:tit])
{

    NSLog(@"Positive");
}
else{
    NSLog(@"Negative");

}

回答5:

Method for compare two strings is isEqualToString:

Your code is like this

NSLog(@"%@", cell.textLabel.text);
NSLog(@"%@", [_dropDownSelection1.elements[1] title]);

if(cell.textLabel.text isEqualToString:[_dropDownSelection1.elements[1] title])
{
NSLog(@"Positive");
}
else
{
NSLog(@"Negative");
}

来源：https://stackoverflow.com/questions/13082427/equal-strings-not-equal

标签

objective-c

ios

nsstring