xcode if else 语句的预期表达式错误
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Expected expression error for if else statement
提问by JSA986
Xcode complains about " Expected expression required" for second else ifstatement in my code. Ive tried using parenthesis from code I had looked at on here but that didn't work and not sure what expression it wants now? Works fine until I add a second else ifI realise this is probably basic objective C stuff but having never done an if statement for more then two items im a bit stuck
Xcode 对else if我的代码中的第二个语句抱怨“需要预期的表达式” 。我试过使用我在此处查看的代码中的括号，但这不起作用，并且不确定它现在想要什么表达式？工作正常，直到我添加第二个else if我意识到这可能是基本的目标 C 的东西，但从来没有为超过两个项目做过 if 语句我有点卡住了
-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
if ([text1 isFirstResponder])return arrStatus.count;
else
if ([text2 isFirstResponder]);return arrStatus2.count;
else ///<<<<< wants an expected expression here
if ([text3 isFirstResponder]);return arrStatus2.count;
}
回答by Alladinian
You just have an extra semicolon on your second ifstatement.
It should be: if ([text2 isFirstResponder]) return arrStatus2.count;
您的第二个if语句中只有一个额外的分号。它应该是：if ([text2 isFirstResponder]) return arrStatus2.count;
PS. You're making the same mistake on the 3rd ifas well... You should really consider using curly brackets even for one-liners.
附注。您在第 3 次if也犯了同样的错误......即使对于单行，您也应该真正考虑使用大括号。
回答by trojanfoe
You have spurious semi-colons after some of the ifstatements:
在某些if语句之后，您有虚假的分号：
if ([text2 isFirstResponder]); <--- here
Other than that your code is poorly indented and you should stop putting statements on the same line as the if/else iflines:
除此之外，您的代码缩进很差，您应该停止将语句与if/else if行放在同一行：
-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
if ([text1 isFirstResponder])
return arrStatus.count;
else if ([text2 isFirstResponder])
return arrStatus2.count;
else if ([text3 isFirstResponder])
return arrStatus2.count;
}
回答by Pieter Gunst
Your function/method is required to return something, in this case an NSInteger. Yet there is a possible situation in your code where there is no return statement. In your last else, if the if statement is not correct, nothing will be returned.
你的函数/方法需要返回一些东西，在这种情况下是一个 NSInteger。然而，您的代码中可能存在没有 return 语句的情况。在你最后的 else 中，如果 if 语句不正确，则不会返回任何内容。
if ([text1 isFirstResponder]) {
return arrStatus.count;
} else {
if ([text2 isFirstResponder]) {
return arrStatus2.count;
} else {
if ([text3 isFirstResponder]) {
return arrStatus2.count;
}
// nothing will be returned here
// you can return nil or actual 0
// return nil;
// return 0;
}
}
}
