fseek Linux 编程手册

#include <stdio.h>#include <stdlib.h> int main(void){    /* Prepare an array of f-p values. */    #define SIZE 5    double A[SIZE] = {1.,2.,3.,4.,5.};    /* Write array to a file. */    FILE * fp = fopen("test.bin", "wb");    fwrite(A,sizeof(double),SIZE,fp);    fclose (fp);     /* Read the f-p values into array B. */    double B[SIZE];    fp = fopen("test.bin","rb");     /* Set the file position indicator in front of third f-p value. */    if (fseek(fp,sizeof(double)*3L,SEEK_SET) != 0)    {       if (ferror(fp))       {          perror("fseek()");          fprintf(stderr,"fseek() failed in file %s at line # %d\n", __FILE__,__LINE__-5);          exit(EXIT_FAILURE);       }    }     int ret_code = fread(B,sizeof(double),1,fp);   /* read one f-p value  */    printf("%.1f\n", B[0]);                        /* print one f-p value */     fclose(fp);    return EXIT_SUCCESS;}

结果输出

4.0

fseek参数解释

stream-file stream to modify 将要改变的文件流offset-number of characters to shift the position relative to origin 相对于origin 位置偏移的字符个数origin-position to which offset is added. It can have one of the following values: SEEK_SET, SEEK_CUR, SEEK_END位置信息：开始，当前以及结尾