什么为c的值，如果c = A，B; [英] What is value of c, if c =a,b;

问题描述

  int类型的= 0;
INT B = 1;
INT C = A，B;
INT D =（A，B）;
 

解决方案

初始化之外，逗号在 A，B 是的逗号运算符和计算结果为 b 。在该行的括号涉及 D 使得这种这种情况。因此，该行实际上只是相当于：

  INT D = B：
 

然而，在涉及 C 行了，这不是用逗号的。相反，它只是一个变量定义的列表，等同于：

  INT C = A;
INT B：
 

（这因此不会编译，因为的重新定义b ！）

int a=0;
int b=1;
int c=a,b;
int d=(a,b);

解决方案

Outside of an initialization, the comma in a,b is the comma operator, and evaluates to b. The parentheses in the line involving d makes this such a case. So that line is really just equivalent to:

int d = b;

However, in the line involving c, this is not a use of the comma operator. Instead, it's just a list of variable definitions, equivalent to:

int c = a;
int b;

(Which consequently will not compile, due to redefinition of b!)

这篇关于什么为c的值，如果c = A，B;的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！