4. 文件的顺序读写
4.1 对比一组函数：
scanf/fscanf/sscanf
rintf/fprintf/sprintf
5. 文件的随机读写
5.1 fseek
根据文件指针的位置和偏移量来定位文件指针。
int fseek ( FILE * stream, long int offset, int origin );
例子：
/* fseek example */ #include <stdio.h> int main () { FILE * pFile; pFile = fopen ( "example.txt" , "wb" ); fputs ( "This is an apple." , pFile ); fseek ( pFile , 9 , SEEK_SET ); fputs ( " sam" , pFile ); fclose ( pFile ); return 0; }
5.2 ftell
返回文件指针相对于起始位置的偏移量
long int ftell ( FILE * stream );
例子：
/* ftell example : getting size of a file */ #include <stdio.h> int main () { FILE * pFile; long size; pFile = fopen ("myfile.txt","rb"); if (pFile==NULL) perror ("Error opening file"); else { fseek (pFile, 0, SEEK_END); // non-portable size=ftell (pFile); fclose (pFile); printf ("Size of myfile.txt: %ld bytes.\n",size); } return 0; }
5.3 rewind
让文件指针的位置回到文件的起始位置
void rewind ( FILE * stream );
例子：
/* rewind example */ #include <stdio.h> int main () { int n; FILE * pFile; char buffer [27]; pFile = fopen ("myfile.txt","w+"); for ( n='A' ; n<='Z' ; n++) fputc ( n, pFile); rewind (pFile); fread (buffer,1,26,pFile); fclose (pFile); buffer[26]='\0'; puts (buffer); return 0; }
