C资料操作-示例代码存放

C文件操作--示例代码存放
from http://blog.csdn.net/lxf464384/archive/2007/10/27/1848714.aspx

Example/* FOPEN.C: This program opens files named "data" * and "data2".It  uses fclose to close "data" and * _fcloseall to close all remaining files. */#include <stdio.h>FILE *stream, *stream2;void main( void ){   int numclosed;   /* Open for read (will fail if file "data" does not exist) */   if( (stream  = fopen( "data", "r" )) == NULL )      printf( "The file 'data' was not opened\n" );   else      printf( "The file 'data' was opened\n" );   /* Open for write */   if( (stream2 = fopen( "data2", "w+" )) == NULL )      printf( "The file 'data2' was not opened\n" );   else      printf( "The file 'data2' was opened\n" );   /* Close stream */   if( fclose( stream ) )      printf( "The file 'data' was not closed\n" );   /* All other files are closed: */   numclosed = _fcloseall( );   printf( "Number of files closed by _fcloseall: %u\n", numclosed );}OutputThe file 'data' was openedThe file 'data2' was openedNumber of files closed by _fcloseall: 1

RemarksThe fseek function moves the file pointer (if any) associated with stream to a new location that is offset bytes from origin. The next operation on the stream takes place at the new location. On a stream open for update, the next operation can be either a read or a write. The argument origin must be one of the following constants, defined in Stdio.h: SEEK_CUR Current position of file pointer SEEK_END End of file SEEK_SET Beginning of file Example/* FSEEK.C: This program opens the file FSEEK.OUT and * moves the pointer to the file's beginning. */#include <stdio.h>void main( void ){   FILE *stream;   char line[81];   int  result;   stream = fopen( "fseek.out", "w+" );   if( stream == NULL )      printf( "The file fseek.out was not opened\n" );   else   {      fprintf( stream, "The fseek begins here: "                       "This is the file 'fseek.out'.\n" );      result = fseek( stream, 23L, SEEK_SET);      if( result )         printf( "Fseek failed" );      else      {         printf( "File pointer is set to middle of first line.\n" );         fgets( line, 80, stream );         printf( "%s", line );      }      fclose( stream );   }}OutputFile pointer is set to middle of first line.This is the file 'fseek.out'.

/**一个c语言文件操作例子代码参考**文件使用方式 　　　　　　　意 义*“rt”　　　　　　只读打开一个文本文件，只允许读数据*“wt”　　　　　　只写打开或建立一个文本文件，只允许写数据*“at”　　　　　　追加打开一个文本文件，并在文件末尾写数据*“rb”　　　　　　只读打开一个二进制文件，只允许读数据*“wb”　　　　 　 只写打开或建立一个二进制文件，只允许写数据*“ab” 　　　　 　追加打开一个二进制文件，并在文件末尾写数据*“rt+”　　　　　 读写打开一个文本文件，允许读和写*“wt+”　　　　　 读写打开或建立一个文本文件，允许读写*“at+”　　　　　 读写打开一个文本文件，允许读，或在文件末追加数 据*“rb+”　　　　　 读写打开一个二进制文件，允许读和写*“wb+”　　　　　 读写打开或建立一个二进制文件，允许读和写*“ab+” 　　　　　读写打开一个二进制文件，允许读，或在文件末追加数据*·字符读写函数 ：fgetc和fputc·字符串读写函数：fgets和fputs·数据块读写函数：freed和fwrite·格式化读写函数：fscanf和fprinf对于文件使用方式有以下几点说明：1. 文件使用方式由r,w,a,t,b，+六个字符拼成，各字符的含义是：r(read): 读w(write): 写a(append): 追加t(text): 文本文件，可省略不写b(banary): 二进制文件*/int main(){FILE *fp;char ch;if((fp=fopen("e10_1.c","rt"))==NULL){printf("Cannot open file strike any key exit!");exit(1);}ch=fgetc(fp);while (ch!=EOF){putchar(ch);ch=fgetc(fp);}fclose(fp);return 0;}

/**二、写字符函数fputc　fputc函数的功能是把一个字符写入指定的文件中，函数调用的  形式为： fputc(字符量，文件指针)； 其中，待写入的字符量可以是字符常量或变量，  例如：fputc('a',fp);其意义是把字符a写入fp所指向的文件中。　 对于fputc函数的使用也要说明几点：1. 被写入的文件可以用、写、读写，追加方式打开，    用写或读写方式打开一个已存在的文件时将清除原有的文件内容，写入字符从文件首开始。如需保留原有文件内容，希望写入的字符以文件末开始存放，必须以追加方式打开文件。被写入的文件若不存在，则创建该文件。2. 每写入一个字符，文件内部位置指针向后移动一个字节。3. fputc函数有一个返回值，如写入成功则返回写入的字符， 否则返回一个EOF。可用此来判断写入是否成功。[例10.2]从键盘输入一行字符，写入一个文件， 再把该文件内容读出显示在屏幕上。*/int main(){FILE *fp;char ch;if((fp=fopen("e10_1.c","wt+"))==NULL){printf("Cannot open file strike any key exit!");exit(1);}printf("input a string:\n");ch=getchar();while (ch!='\n'){fputc(ch,fp);ch=getchar();}rewind(fp);ch=fgetc(fp);while(ch!=EOF){putchar(ch);ch=fgetc(fp);}printf("\n");fclose(fp);return 0;}