如果调用 fclose(0)，这会关闭标准输入吗？

如果调用 fclose(0)，这会关闭标准输入吗？

我问这个问题的原因是由于某种原因，stdin 在我的应用程序中被关闭，我不明白为什么。我检查了 fclose (stdin)，但这不在应用程序中，所以我想知道 fclose(0) 是否会导致未定义的行为，例如关闭 stdin？

如果没有，stdin 可能被错误关闭的其他方式是什么？

的签名fclose这是：

int fclose ( FILE * stream );

That means, fclose expects a pointer to FILE object. So if you pass 0, instead of a pointer, 0 would be understood as NULL pointer¹. If its NULL pointer, how do you expect it to close stdin? It will not close. Use fclose(stdin), as stdin itself is a pointer to FILE object.

我觉得你很困惑stdin具有整数类型的文件描述符，通常表示为fd。确实如此fd输入流的0。所以如果你想使用fd（代替FILE*），那么你必须使用close from <unistd.h>.

#include <unistd.h>
int close(int fildes);

那是，close(0)将关闭标准输入。

_{1 : It seems interesting that if you had passed 1 to fclose with the intention to close stdout, your code wouldn't even compile, and you would immediately see the problem with your code at compile-time itself. Now the question is, why would it not compile? Because unlike 0, 1 is not implicitly converted into pointer type. The compiler would generate message like "error: invalid conversion from ‘int’ to ‘FILE*’. See the error and line number here at ideone http://www.ideone.com/mz0yx.}