当变量被遮盖时得到警告 [英] Get warning when a variable is shadowed

问题描述

我通常想避免这样的代码：

I generally want to avoid code like this:

#include <stdio.h>

int main(int argc, char *argv[]){

  int n = 3;

  for (int n = 1; n <= 10; n++){
    printf("%d\n", n);
  }

  printf("%d\n", n);
}

如何找到变量的这种用法？这意味着在同一个函数中，局部变量与全局变量具有相同的名称吗？

How can I find such usage of variables? That means, that in the same function a "more local" variable has the same name as a more global variable?

C-Standard：C 99

C-Standard : C 99

推荐答案

gcc和clang都支持 -Wshadow 标志，该标志将警告那些隐藏了一个的变量另一个。例如，我从 gcc 收到的关于您的代码的警告如下：

Both gcc and clang support the -Wshadow flag which will warn about variables that shadow one another. For example the warning I receive from gcc for your code is the following:

warning: declaration of ‘n’ shadows a previous local [-Wshadow]
for (int n = 1; n <= 10; n++){
         ^
warning: shadowed declaration is here [-Wshadow]
int n = 3;
    ^

gcc 记录了在此处标记并说：

每当局部变量或类型声明遮盖另一个
变量，参数，类型，类成员（在C ++中）或实例变量
（在Objective-C中）或当内置功能被遮盖。请注意
，在C ++中，编译器会在局部变量遮盖
显式typedef时发出警告，但在遮盖struct / class / enum时不会发出警告。

Warn whenever a local variable or type declaration shadows another variable, parameter, type, class member (in C++), or instance variable (in Objective-C) or whenever a built-in function is shadowed. Note that in C++, the compiler warns if a local variable shadows an explicit typedef, but not if it shadows a struct/class/enum.

在Visual Studio中，这似乎以前是不可能的，但是

In Visual Studio this looks like it was not possible before but seems to be fixed in recent versions.

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