我可以在for循环的初始化中声明不同类型的变量吗？ [英] Can I declare variables of different types in the initialization of a for loop?

问题描述

为什么这个C ++代码不能在VS2010下编译：

Why does this C++ code not compile under VS2010:

for ( int a = 0, short b = 0; a < 10; ++a, ++b ) {}

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while this one does:

short b = 0;
for ( int a = 0; a < 10; ++a, ++b ) {}

是否禁止在循环初始化中的不同类型的两个变量的声明？

Is the declaration of two variables of different types inside the for-loop initializer prohibited? If so, how can you work around it?

推荐答案

是的，这是禁止的。正如在其他方面你不能在一个声明语句中声明不同类型的变量（ edit ：modulo @MrLister提到的声明器修饰符）。您可以为（struct {int a = 0; short b = 0;} d; da <10;}声明结构

Yes, that is prohibited. Just as otherwise you cannot declare variables of differing types in one declaration statement (edit: modulo the declarator modifiers that @MrLister mentions). You can declare structs

for (struct { int a = 0; short b = 0; } d; d.a < 10; ++d.a, ++d.b ) {}

C ++ 03代码：

C++03 code:

for (struct { int a; short b; } d = { 0, 0 }; d.a < 10; ++d.a, ++d.b ) {}

当然，当 0 ，您可以完全省略初始值设置，并写 = {} 。

Of course when all are 0, you can omit the initializers altogether and write = { }.

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