本文介绍了哪些事件可能导致错误返回非零值?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧! 问题描述 哪些事件可能导致 ferror()返回非零值,并且在哪些事件之后应该检查 ferror()?What events can cause ferror() to return non-zero and after what events should one check ferror()? http:// www .cplusplus.com / reference / cstdio / ferror / 打开,阅读,关闭? ferror()的返回值会自发改变吗?例如,如果程序检查 ferror(stream),则小睡片刻而不与与 FILE 对象进行交互c $ c> stream ,然后再次检查 ferror(stream),返回值是否会有所不同?Will the return value of ferror() ever change spontaneously? E.g., if a program checks ferror(stream), takes a nap without interacting with the FILE object associated with stream, and then checks ferror(stream) again, will the return value ever be different?其中任何一项是由标准强制执行的吗?Is any of this mandated by standards?推荐答案主要是底层系统返回的错误调用(例如 read , write , lseek , close ),这将导致流的错误位被设置。It is primarily errors returned from the underlying system calls (e.g. read, write, lseek, close) that will cause the stream's error bit to be set.很多 f ___() stdio.h 中的/ code>函数表明,如果到达文件末尾或发生错误,则 ferror() 或 feof()将说明原因。 fscanf ,例如:Many f___() functions from stdio.h indicate that if the end-of-file is reached, or an error occurs, ferror() or feof() will indicate why. fscanf, for example: 如果输入结束,则返回值 EOF 在首次成功转换或匹配失败发生之前到达。如果发生读取错误,也会返回 EOF ,在这种情况下,流的错误指示符(请参见 ferror( 3)设置),并设置 errno 表示错误。 The value EOF is returned if the end of input is reached before either the first successful conversion or a matching failure occurs. EOF is also returned if a read error occurs, in which case the error indicator for the stream (see ferror(3)) is set, and errno is set indicate the error. stdio.h 中的函数是同步的-没有后台线程在做什么,所以不,错误位(从 ferror())永远不会自发改变。 Functions from stdio.h are synchronous - there's no background thread doing anything, so no, the error bit (returned from ferror()) will never spontaneously change. It will only be affected by a call to libc by your application.对于非常好奇的人,可以克隆GLibc。 Git存储库( git://sourceware.org/git/glibc.git )并查看代码本身。 For the very curious, one could clone the GLibc Git repository (git://sourceware.org/git/glibc.git) and have a look at the code itself. ferror()本质上只是检查 _IO_ERR_SEEN 文件的 _flags 字段中的位。 grep 表示该常数将向您显示已设置/清除的所有位置。ferror() essentially just checks for the _IO_ERR_SEEN bit in the file's _flags field. greping for that constant will show you all of the places it is set/cleared. 这篇关于哪些事件可能导致错误返回非零值?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持! 09-17 10:44