如何初始化一个为（;;）在空调回路几个变量？ [英] How to initialize several variables in a for (;;) loop in C?

问题描述

我认为人们可以在为环路初始化几个变量：

I thought one could initialize several variables in a for loop:

for (int i = 0, char* ptr = bam; i < 10; i++) { ... }

不过，我刚刚发现这是不可能的，GCC提供了以下错误：

But I just found out that this is not possible, gcc gives the following error:

error: expected unqualified-id before 'char'

难道真的，你不能在为环路初始化不同类型的变量？

Is it really true that you can't initialize variables of different types in a for loop?

推荐答案

您可以（但一般不宜）使用当地的结构类型。

You can (but generally shouldn't) use an local struct type.

for ( struct { int i; char* ptr; } loopy = { 0, bam };
      loopy.i < 10 && * loopy.ptr != 0;
      ++ loopy.i, ++ loopy.ptr )
    { ... }

---

由于C ++ 11，你可以更优雅初始化各个部分，只要它们不依赖于一个局部变量：

---

Since C++11, you can initialize the individual parts more elegantly, as long as they don't depend on a local variable:

for ( struct { int i = 0; std::string status; } loop;
      loop.status != "done"; ++ loop.i )
    { ... }

这是只是几乎足以可​​读性真正使用。

This is just almost readable enough to really use.

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