Xcode does not give an error of my (thought-to-be) typo:
Xcode没有给出我(想要)打错的错误:
NSString *theme = [[NSUserDefaults standardUserDefaults] objectForKey:@"theme"];
NSLog(@"Theme: %@", theme ?: @"Default");
It turns out:
事实证明:
NSLog(@"Theme: %@", theme ?: @"Default");
works same as:
是一样的:
NSLog(@"Theme: %@", theme ? theme : @"Default");
Is the above shorten syntax good for gcc only? Or it is part of Objective-C?
上述缩短语法仅适用于gcc吗?或者它是Objective-C的一部分?
1 个解决方案
#1
17
It's a GNU extension to the conditional expression in C:
它是对C中的条件表达式的GNU扩展:
From here:
从这里开始:
A GNU extension to C allows omitting the second operand, and using implicitly the first operand as the second also:
GNU扩展到C允许省略第二个操作数，并且隐式地使用第一个操作数作为第二个操作数:
a = x ? : y;
#1
17
It's a GNU extension to the conditional expression in C:
它是对C中的条件表达式的GNU扩展:
From here:
从这里开始:
A GNU extension to C allows omitting the second operand, and using implicitly the first operand as the second also:
GNU扩展到C允许省略第二个操作数，并且隐式地使用第一个操作数作为第二个操作数:
a = x ? : y;