c - C编译器如何解释以下代码序列

Question

这个问题已经有答案了:

What does the comma operator , do? (8 个回答)

已关闭 7 年前。

我有这个 C 代码行:

int a;
a = (1, 2, 3);

printf("%d", a);

为什么值 3被打印？ (最后一个)。

Answer 1

逗号运算符计算其所有“成员”，但返回最后一个表达式的值。
来自 C11 标准:

The left operand of a comma operator is evaluated as a void expression; there is a sequence point between its evaluation and that of the right operand. Then the right operand is evaluated; the result has its type and value.