fseek 是做什么的？
What does fseek do?
我是 C 的新手，正在使用 fseek。我的问题是，它到底有什么作用？
例如：fseek(FILE *stream, -1, SEEK_CUR) 将向后读取 1 个字符，那么它是否已经在文件末尾？
这是否意味着 fseek(FILE *stream, 0, SEEK_CUR) 什么都不做？
我们如何将 fseek 之后的函数应用于数据结构？
I'm new to C and am using fseek. My question is, what exactly does it do?
fseek 为 stream 指向的流设置文件位置指示符。新位置将由偏移量结合标志给出：
对于SEEK_SET，偏移量是相对于文件的开头。
对于SEEK_CUR，偏移量是相对于当前指标位置的。
对于SEEK_END它是相对于文件结尾的。
eg: fseek(FILE *stream, -1, SEEK_CUR) will read 1 character backwards, so is it already at the end of the file?
可能在开头，可能在中间，也可能在结尾，当前位置就是现在所在的位置。如果指标位于文件末尾，它将向后移动一个字节。
它不读取字符，如前所述，它将指示器从当前位置偏移到所需位置，如上所述。
Does that mean fseek(FILE *stream, 0, SEEK_CUR) does nothing?
实际上它没有做任何可见的事情，因为偏移量为 0 它不移动指标，它只是将它放在相同的位置。它确实清除文件结束状态（重置 EOF 标志 ）。
来自 C11 N1570 §7.21.9.2
#include <stdio.h>
int fseek(FILE *stream, long int offset, int whence);
Description:
2 The fseek function sets the file position indicator for the stream pointed to by stream. If a read or write error occurs, the error indicator for the stream is set and fseek fails.
3 For a binary stream, the new position, measured in characters from the beginning of the file, is obtained by adding offset to the position specified by whence. The specified position is the beginning of the file if whence is SEEK_SET, the current value of the file position indicator if SEEK_CUR, or end-of-file if SEEK_END. A binary stream need not meaningfully support fseek calls with a whence value of SEEK_END.
4 For a text stream, either offset shall be zero, or offset shall be a value returned by an earlier successful call to the ftell function on a stream associated with the same file and whence shall be SEEK_SET.
5 After determining the new position, a successful call to the fseek function undoes any effects of the ungetc function on the stream, clears the end-of-file indicator for the stream, and then establishes the new position. After a successful fseek call, the next operation on an update stream may be either input or output.
Returns:
6 The fseek function returns nonzero only for a request that cannot be satisfied.
我是 C 的新手，正在使用 fseek。我的问题是，它到底有什么作用？
例如：fseek(FILE *stream, -1, SEEK_CUR) 将向后读取 1 个字符，那么它是否已经在文件末尾？
这是否意味着 fseek(FILE *stream, 0, SEEK_CUR) 什么都不做？
我们如何将 fseek 之后的函数应用于数据结构？
I'm new to C and am using
fseek. My question is, what exactly does it do?
fseek 为 stream 指向的流设置文件位置指示符。新位置将由偏移量结合标志给出：
对于
SEEK_SET，偏移量是相对于文件的开头。对于
SEEK_CUR，偏移量是相对于当前指标位置的。对于
SEEK_END它是相对于文件结尾的。
eg:
fseek(FILE *stream, -1, SEEK_CUR)will read 1 character backwards, so is it already at the end of the file?
可能在开头，可能在中间，也可能在结尾，当前位置就是现在所在的位置。如果指标位于文件末尾，它将向后移动一个字节。
它不读取字符，如前所述，它将指示器从当前位置偏移到所需位置，如上所述。
Does that mean
fseek(FILE *stream, 0, SEEK_CUR)does nothing?
实际上它没有做任何可见的事情，因为偏移量为 0 它不移动指标，它只是将它放在相同的位置。它确实清除文件结束状态（重置 EOF 标志
来自 C11 N1570 §7.21.9.2
#include <stdio.h> int fseek(FILE *stream, long int offset, int whence);Description:
2 The
fseekfunction sets the file position indicator for the stream pointed to bystream. If a read or write error occurs, the error indicator for the stream is set andfseekfails.
3 For a binary stream, the new position, measured in characters from the beginning of the file, is obtained by adding offset to the position specified bywhence. The specified position is the beginning of the file ifwhenceisSEEK_SET, the current value of the file position indicator ifSEEK_CUR, or end-of-file ifSEEK_END. A binary stream need not meaningfully support fseek calls with awhencevalue ofSEEK_END.
4 For a text stream, eitheroffsetshall be zero, oroffsetshall be a value returned by an earlier successful call to the ftell function on a stream associated with the same file andwhenceshall beSEEK_SET.
5 After determining the new position, a successful call to thefseekfunction undoes any effects of the ungetc function on the stream, clears the end-of-file indicator for the stream, and then establishes the new position. After a successfulfseekcall, the next operation on an update stream may be either input or output.Returns:
6 The
fseekfunction returns nonzero only for a request that cannot be satisfied.