c - 当变量被隐藏时得到警告

Question

我通常想避免这样的代码:

#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，“更局部”的变量与更全局的变量具有相同的名称？

C-标准:C 99

Answer 1

gcc 和 clang 都支持 -Wshadow 标志，该标志将警告相互遮蔽的变量。例如，我从 gcc 收到的针对您的代码的警告如下:

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 记录标志 here并说:

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 中这看起来以前是不可能的，但是 seems to be fixed in recent versions .