NAME

fread, fwrite - 二進(jìn)制流的輸入/輸出  

總覽 (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);  

描述 (DESCRIPTION)

函數(shù) fread 從 stream 指定 的 流 里面 讀取 nmemb 個(gè) 數(shù)據(jù)單元, 每個(gè) 單元 有 size 個(gè) 字節(jié), 然后 存放在 ptr 指定 的 數(shù)據(jù)區(qū).

函數(shù) fwrite 向 stream 指定 的 流 輸出 nmemb 個(gè) 數(shù)據(jù)單元, 每個(gè) 單元 有 size 個(gè) 字節(jié), 數(shù)據(jù) 來源 由 ptr 指針 指出.

相應(yīng)的 無(wú)鎖函數(shù)(non-locking) 參見 unlocked_stdio(3).  

返回值 (RETURN VALUE)

fread 和 fwrite 返回 成功 讀/寫 的 單元數(shù) (也就是說, 不是字節(jié)數(shù)). 如果 出現(xiàn) 錯(cuò)誤 或 到達(dá)文件末尾, 函數(shù) 返回 縮小的 單元數(shù) (或0).

fread 不能 區(qū)分 錯(cuò)誤 和 文件末尾, 調(diào)用者 必須 通過 feof(3) 和 ferror(3) 判斷 發(fā)生了 什么.  

參考標(biāo)準(zhǔn) (CONFORMING TO)

函數(shù) fread 和 fwrite 遵循 ANSI X3.159-1989 (``ANSI C'').  

另見 (SEE ALSO)

read(2), write(2), feof(3), ferror(3), unlocked_stdio(3)  

#p#

NAME

fread, fwrite - binary stream input/output  

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.

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.

For non-locking counterparts, see unlocked_stdio(3).  

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 does not distinguish between end-of-file and error, and callers must use feof(3) and ferror(3) to determine which occurred.  

CONFORMING TO

The functions fread and fwrite conform to ANSI X3.159-1989 (``ANSI C'').  

SEE ALSO

read(2), write(2), feof(3), ferror(3), unlocked_stdio(3)