"f"表示号码后 [英] "f" after number

问题描述

数字后的f表示什么?这是C还是Objective-C的?不将其加到常数上有什么区别吗?

What does the f after the numbers indicate? Is this from C or Objective-C? Is there any difference in not adding this to a constant number?

CGRect frame = CGRectMake(0.0f, 0.0f, 320.0f, 50.0f);

你能解释为什么我不只是写:

Can you explain why I wouldn't just write:

CGRect frame = CGRectMake(0, 0, 320, 50);

推荐答案

CGRect frame = CGRectMake(0.0f, 0.0f, 320.0f, 50.0f);

使用浮点常量. (常数0.0通常在Objective-C中声明一个双精度；在末尾加一个f-0.0f-将该常数声明为(32位)浮点数.)

uses float constants. (The constant 0.0 usually declares a double in Objective-C; putting an f on the end - 0.0f - declares the constant as a (32-bit) float.)

CGRect frame = CGRectMake(0, 0, 320, 50);

使用整数，该整数将自动转换为浮点数.

uses ints which will be automatically converted to floats.

在这种情况下，两者之间没有(实际的)区别.

In this case, there's no (practical) difference between the two.

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