C语言库函数pread pwrite

最新推荐文章于 2025-05-12 18:55:27 发布

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最新推荐文章于 2025-05-12 18:55:27 发布

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分类专栏： C语言

本文链接：https://blog.youkuaiyun.com/qq_23929673/article/details/95725002

本文详细探讨了C语言中的库函数pread和pwrite，如何利用它们进行文件的直接读写操作，特别是在处理结构体数据时，能够直接将结构体内容写入文件并直接读取，避免了额外的数据拆解步骤。

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这里注意一下，结构以结构的格式写入文件，获取的时候可以直接赋值给结构，不需要中间获取再拆解

NAME
       pread, pwrite - read from or write to a file descriptor at a given offset

SYNOPSIS
       #include <unistd.h>

       ssize_t pread(int fd, void *buf, size_t count, off_t offset);

       ssize_t pwrite(int fd, const void *buf, size_t count, off_t offset);

DESCRIPTION
       pread() reads up to count bytes from file descriptor fd at offset offset (from the start of the file) into the buffer starting at buf.  The file offset is not changed.

       pwrite() writes up to count bytes from the buffer starting at buf to the file descriptor fd at offset offset.  The file offset is not changed.

       The file referenced by fd must be capable of seeking.

RETURN VALUE
       On  success, the number of bytes read or written is returned (zero indicates that nothing was written, in the case of pwrite(), or end of file, in the case of pread()), or -1
       on error, in which case errno is set to indicate the er