fseek Linux 编程手册

最新推荐文章于 2025-10-28 09:36:01 发布

转载最新推荐文章于 2025-10-28 09:36:01 发布 · 333 阅读

C 同时被 2 个专栏收录

6 篇文章

订阅专栏

linux

6 篇文章

订阅专栏

本文通过一个C语言程序示例介绍了如何使用fseek和fread函数定位并读取二进制文件中的浮点数值。该程序首先创建了一个包含浮点数的数组，并将其写入二进制文件中。接着，程序利用fseek定位到第三个浮点数的位置，并使用fread读取该数值。文章详细展示了文件指针定位和读取的具体步骤。

#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