如何为二进制和ASCII文件定义EOF [英] How EOF is defined for binary and ascii files

问题描述

我正在Windows(系统语言是日语)上编写C语言，但是我对二进制文件和ascii文件的EOF有疑问.

I'm programming C on Windows(system language is Japanese), and I have a problem about EOF of binary and ascii files.

上周我问了这个问题，一个好心人帮了我，但是我仍然无法真正理解程序在读取二进制文件或ascii文件时的工作方式.

I asked this question last week, a kind guy helped me, but I still can't really understand how the program works when reading a binary or an ascii file.

我做了以下测试:

Test1:

int oneChar;
iFile = fopen("myFile.tar.gz", "rb");
while ((oneChar = fgetc(iFile)) != EOF) {
        printf("%d ", oneChar);
}

Test2:

int oneChar;
iFile = fopen("myFile.tar.gz", "r");
while ((oneChar = fgetc(iFile)) != EOF) {
        printf("%d ", oneChar);
}

在test1情况下，对于二进制文件和ascii文件，一切运行正常.但是在test2中，程序在二进制文件中遇到 0x1A 时停止读取. (这是否表示 1A == EOF ??)ASCII表告诉我1A是一个称为 substitute 的控制字符(无论什么意思……)，当我printf( (％d"，EOF)，但是它给了我 -1 ...

In the test1 case, things worked perfectly for both binary and ascii files. But in test2, program stopped reading when it encountered 0x1A in a binary file. (Does this mean that 1A == EOF?) ASCII table tells me that 1A is a control character called substitute (whatever that means...) And when I printf("%d", EOF), however, it gave me -1...

我还发现了此问题，告诉我操作系统确切知道文件的结尾，所以我真的不需要在文件中找到EOF，因为EOF超出了字节范围(大约1A?)

I also found this question which tells me that the OS knows exactly where a file ends, so I don't really need to find EOF in the file, because EOF is out of the range of a byte (what about 1A?)

有人可以帮我清理一下吗?预先感谢.

Can someone clear things up a little for me? Thanks in advance.

推荐答案

这是Windows特定于文本文件的技巧:SUB字符，由 Ctrl + Z表示序列被fgetc解释为EOF.您不必在文本文件中包含1A即可从fgetc取回EOF，但是:一旦到达文件的实际末尾，将返回EOF.

This is a Windows-specific trick for text files: SUB character, which is represented by Ctrl+Z sequence, is interpreted as EOF by fgetc. You do not have to have 1A in your text file in order to get an EOF back from fgetc, though: once you reach the actual end of file, EOF would be returned.

标准未将1A定义为char值来表示EOF. EOF的常量的类型为int，其负值超出unsigned char的范围.实际上，fgetc返回int而不是char的原因是让它返回EOF的特殊值.

The standard does not define 1A as the char value to represent an EOF. The constant for EOF is of type int, with a negative value outside the range of unsigned char. In fact, the reason why fgetc returns an int, not char, is to let it return a special value for EOF.

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