如果我忘记为文件指针分配空值，如何检查文件是否打开 [英] How to check a file is opened or not if i forgot to assign null to file pointer

问题描述

我已经打开文件

FILE *fp = fopen("file.txt","r");
fclose(fp);

场景是我忘记为fp分配空值 现在，我想使用相同的fp指针

scenario is that I forgot to assign null to fp Now I want to check whether this file is open or not using same fp pointer

推荐答案

您不能. fp的值在关闭后不确定: http://www.iso -9899.info/n1256.html#7.19.3p4

You can't. The value of fp after closing it is indeterminate: http://www.iso-9899.info/n1256.html#7.19.3p4

这意味着对其进行任何操作都会导致未定义的行为.

This means any operation on it results in undefined behaviour.

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