fread (翻译 man 3)-优快云博客

//注意：
//1 完成次写操(fwrite())作后必须关闭流(fclose());
//2 完成一次读操作(fread())后，如果没有关闭流(fclose()),则指针(FILE * fp)自动向后移动前一次读写的长度，
//不关闭流继续下一次读操作则接着上次的输出继续输出;
//3 fprintf() ：按格式输入到流，其原型是int fprintf(FILE *stream, const char *format[, argument, ...]);
//其用法和printf()相同，不过不是写到控制台，而是写到流罢了。注意的是返回值为此次操作写入到文件的字节数。
//如int c = fprintf(fp, "%s %s %d %f", str1,str2, a, b) ;str1：10字节；str2： 10字节；a：2字节；b：8字节，c为33，
//因为写入时不同的数据间自动加入一个空格。

FREAD(3)                      Linux Programmer's Manual                      FREAD(3)

NAME

       fread, fwrite - binary stream input/output

//二进制流的输入输出

SYNOPSIS

       #include <stdio.h>

       size_t fread(void *ptr, size_t size, size_t nmemb, FILE *stream);

       size_t fwrite(const void *ptr, size_t size, size_t nmemb,
                     FILE *stream);

DESCRIPTION

       The function fread() reads nmemb elements of data, each size bytes long, from
       the stream pointed to by stream, storing them at the location given by ptr.
//fread()从stream指向的流中读出nmemb个元素,每次size个,存储在ptr指定的区域内
       The function fwrite() writes nmemb elements of data, each size bytes long, to
       the stream pointed to by stream, obtaining them from the location given by
       ptr.
//fwrite()向stream指向的流中写入nmemb个元素,每次size个,从ptr指定的区域内得到的数据
       For nonlocking counterparts, see unlocked_stdio(3).

//对于非锁定的情况,使用see unlocked_stdio()

RETURN VALUE

       fread() and fwrite() return the number of items successfully read or written
       (i.e., not the number of characters).  If an error occurs, or the end-of-file
       is reached, the return value is a short item count (or zero).
//fread() 和 fwrite()返回成功读和写的数目(不是字符的数目).当错误发生或者遇到EOF,返回值是
//short类型?(或者是0)
       fread() does not distinguish between end-of-file and error, and callers must
       use feof(3) and ferror(3) to determine which occurred.

//fread()并不辨别EOF和error,调用者必须使用feof(3) 和 ferror(3)来判断到底是哪个发生了.

CONFORMING TO

       C89, POSIX.1-2001.

COLOPHON

       This page is part of release 3.29 of the Linux man-pages project.  A
       description of the project, and information about reporting bugs, can be found
       at http://www.kernel.org/doc/man-pages/.

GNU                                   1996-05-17                             FREAD(3)