FOPEN

NAME
SYNOPSIS æ»è§
DESCRIPTION æè¿°
RETURN VALUE è¿åå¼
ERRORS
CONFORMING TO æ ååè
SEE ALSO åè§
è·

---

NAME

fopen, fdopen, freopen - æå¼æµ

SYNOPSIS æ»è§

#include <stdio.h>

FILE *fopen(const char *path, const char *mode);
FILE *fdopen(int fildes, const char *mode);
FILE *freopen(const char *path, const char *mode, FILE *stream);

DESCRIPTION æè¿°

å½æ° fopen æå¼æ件å为 path æåçå符串çæ件ï¼å°ä¸ä¸ªæµä¸å®å³èã

åæ° mode æåä¸ä¸ªå符串ï¼ä»¥ä¸ååºåä¹ä¸å¼å§ (åºåä¹åå¯ä»¥æéå çå符):

	r		æå¼ææ¬æ件ï¼ç¨äºè¯»ãæµè¢«å®ä½äºæ件çå¼å§ã
	r+		æå¼ææ¬æ件ï¼ç¨äºè¯»åãæµè¢«å®ä½äºæ件çå¼å§ã
	w		å°æ件é¿åº¦æªæ为é¶ï¼æèå建ææ¬æ件ï¼ç¨äºåãæµè¢«å®ä½äºæ件çå¼å§ã
	w+		æå¼æ件ï¼ç¨äºè¯»åãå¦ææ件ä¸åå¨å°±å建å®ï¼å¦åå°æªæ- å®ãæµè¢«å®ä½äºæ件çå¼å§ã
	a		æå¼æ件ï¼ç¨äºè¿½å  (å¨æ件尾å)ãå¦ææ件ä¸å- å¨å°±å建å®ãæµè¢«å®ä½äºæ件çæ«å°¾ã
	a+		æå¼æ件ï¼ç¨äºè¿½å  (å¨æ件尾å)ãå¦ææ件ä¸å- å¨å°±å建å®ã读æ件çåå§ä½ç½®æ¯æ件çå¼å§ï¼ä½æ¯è¾åºæ»æ¯è¢«è¿½åå°æ件çæ«å°¾ã

å符串 mode ä¹å¯ä»¥åå«åæ¯ ‘‘b’’ ä½ä¸ºæåä¸ä¸ªå- 符ï¼æèæå¥å°ä¸é¢æå°çä»»ä½åå符çå符串ç两个å符ä¸é´ãè¿æ ·åªæ¯ä¸ºäºå ANSI X3.159-1989 (‘‘ANSI C’’) æ å严格ä¿æå¼å®¹ï¼æ²¡æå®éçææï¼å¨ææçéµå¾ª POSIX çç³»ç»ä¸ï¼‘‘b’’ é½è¢«å¿½ç¥ï¼åæ¬ Linuxã(å¶ä»ç³»ç»å¯è½å°ææ¬æ件åäºè¿å¶æ件åºå«å¯¹å¾ï¼å¦æå¨è¿è¡äºè¿å¶æ件ç I/Oï¼é£ä¹æ·»å  ‘‘b’’ æ¯ä¸ªå¥½ä¸»æï¼å ä¸ºä½ çç¨åºå¯è½ä¼è¢«ç§»æ¤å°é Unix ç¯å¢ä¸ã)

ä»»ä½æ°å»ºçæ件å°å·ææ¨¡å¼ S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH (0666)ï¼ç¶å以è¿ç¨çæ©ç å¼ umask å ä»¥ä¿®æ¹ (åè§ umask(2)) ã

å¨è¯»/åæµä¸è¿è¡ç读ååæä½å¯ä»¥ä»¥ä»»æç顺åºæ··å使ç¨ã注æ ANSI C è¦æ±æ件å®ä½å½æ°åªè½æå¥å¨è¾åºåè¾å¥ä¹é´ï¼é¤éè¾å¥æä½éå°äºæ件ç»æ符ã(å¦æ没æéå°è¿ç§æåµï¼é£ä¹è¯»åæ»æ¯è½è¿åé¤äºæè¿åå¥å容ä¹å¤çç»æã) å æ¤ï¼æ好 (å¨ Linux ä¸ææ¶æ¯å¿é¡»ç) å¨å¯¹è¿æ ·çæµè¿è¡çåå读æä½ä¹é´å å¥ä¸ä¸ª fseek ææ¯ fgetpos æä½ãè¿ä¸ªæä½å¯ä»¥æ¯å¯¹æ¾å¼çå®ä½çè°ç¨ (ä¾å¦å¨ fseek(..., 0L, SEEK_CUR) ä¸é£æ ·)ï¼å©ç¨åæ¶åççå¯ä½ç¨ã(?)

以追å æ¹å¼æå¼æ件 (以 a ä½ä¸º mode ç第ä¸ä¸ªå符) å°ä½¿å¾ææåç»- ç对è¿ä¸ªæµçåæä½åçå¨æ件æ«å°¾ï¼å°±å¥½åå¨åä¹åè°ç¨äº

fseek(stream,0,SEEK_END);

ä¸æ ·ã

å½æ° fdopen å°ä¸ä¸ªæµå³èå°å·²åå¨çæ件æè¿°ç¬¦ï¼ fildes. æµçæ¨¡å¼ mode (åå¼ä¸º "r", "r+", "w", "w+", "a", "a+" ä¹ä¸) å¿é¡»ä¸æ件æ述符ç模å¼æ³å¹éãæ°çæµçå®ä½æ è¯è¢«è®¾ç½®ä¸º fildes åæçå¼ï¼é误åæ件ç»ææ è®°è¢«æ¸é¤ãæ¨¡å¼ "w" æè "w+" ä¸ä¼æªæ- æ件ãæ件æ述符ä¸ä¼è¢«å¤å¶ï¼å¨å³éç± fdopen å建çæµæ¶ï¼ä¹ä¸ä¼è¢«å³é- ã对å±äº«åå对象å®æ½ fdopen çç»ææ¯æªå®ä¹çã

å½æ° freopen æå¼å称为 path æåçå符串çæ件ï¼å°å®ä¸ stream æåçæµå³èãåå§çæµ (å¦æåå¨çè¯) 被å³éãåæ° mode ä¸å¨å½æ° fopen ä¸- ç¨æ³ä¸è´ãå½æ° freopen 主è¦çç¨å¤æ¯æ¹åä¸æ åææ¬æµ (stderr, stdin, æ stdout) ç¸å³èçæ件

RETURN VALUE è¿åå¼

å¦ææåæ§è¡äº fopen, fdopen å freopen å°è¿åä¸ä¸ªæåæ件对象 FILE çæéãå¦åï¼å°è¿å NULL 并å°è®¾ç½®å¨å±åé errno çå¼æ¥æ示é误åçã

ERRORS

EINVAL

为 fopen, fdopen, æ freopen æä¾çåæ° mode éæ³ã

å½æ° fopen, fdopen å freopen ä¹æå¯è½å¤±è´¥å¹¶ç½® errno 为 malloc(3) æå®çå¼ã

å½æ° fopen ä¹æå¯è½å¤±è´¥å¹¶ç½® errno 为 open(2) æå®çå¼ã

å½æ° fdopen ä¹æå¯è½å¤±è´¥å¹¶ç½® errno 为 fcntl(2) æå®çå¼ã

å½æ° freopen ä¹æå¯è½å¤±è´¥å¹¶ç½® errno 为 open(2), fclose(3) å fflush(3) æå®çå¼ã

CONFORMING TO æ ååè

å½æ° fopen å freopen éµå¾ª ANSI X3.159-1989 (‘‘ANSI C’’) æ åãå½æ° fdopen éµå¾ª IEEE Std1003.1-1988 (‘‘POSIX.1’’) æ åã

SEE ALSO åè§

open(2), fclose(3), fileno(3)

è·

æ¬é¡µé¢ä¸æçç±ä¸æ man æå页计åæä¾ã
ä¸æ man æå页计åï¼https://github.com/man-pages-zh/manpages-zh

---