VC文件读写函数.doc.docVIP

VC文件函数 1．文件的打开函数FILE *fopen( const char *filename, const char *mode );FILE *_wfopen( const wchar_t *filename, const wchar_t *mode );参数：filename 文件的名称mode 打开文件的模式返回值：成功的打开文件的话返回 文件的指针 否则返回NULL表示打开文件错误注：r 只读方式打开w 以写入方式打开a 从文件的尾端写入数据，要是文件不存在则创建后写入数据r+ 以读写方式打开（文件必须存在）w+ 打开一个可以读写的文件，如果该文件存在则覆盖写入a+ 打开文件并追加写入源于stdio.h实例：#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 );}输出：The file data was openedThe file data2 was openedNumber of files closed by _fcloseall: 1 2．当前文件指针位置获取函数long ftell( FILE *stream );参数：stream 文件指针返回值：当前文件指针的位置实例：#include stdio.h FILE *stream; void main( void ){?? long position;?? char list[100];?? if( (stream = fopen( ftell.c, rb )) != NULL )?? {????? /* Move the pointer by reading data: */????? fread( list, sizeof( char ), 100, stream );????? /* Get position after read: */????? position = ftell( stream );????? printf( Position after trying to read 100 bytes: %ld\n,????????????? position );????? fclose( stream );?? }}输出：Position after trying to read 100 bytes: 100 3.文件读取函数size_t fread( void *buffer, size_t size, size_t count, FILE *stream )参数： buffer 文件读取缓冲区 size 读取数据的类型 count 读取数据的个数 stream 文件指针返回值：实际读取的数据个数源于stdio.h例子：FILE* fp;char* buffer=new char[1024];long realLength=fread(buffer,sizeof(char),1024,fp);////处理过程//delete buffer;fclose(fp); 4.文件的写入函数size_t fwrite( co