学习笔记第八章文件

12月

8.1 文件输入输出

linux 用 > 和 < 做重定向

$></cat_post_image><ul><li>打开文件的标准代码：</li></ul><pre><code> FILE *fp = fopen("file","r"); if(fp){ fscanf(fp,...); fclose(fp); }else{ ... }</code></pre><ul><li>Example 01：</li></ul><pre><code> #include <stdio.h> int main(int argc,char const *argv[]){ FILE *fp = fopen("12.in","r"); if(fp){ int num; fscanf(fp,"%d",&num); printf("%d\n",num); fclose(fp); } else{ printf("无法打开文件\n"); } return 0; }</code></pre><h3>fopen</h3><cat_post_image><img src=$

8.4 文件中定位

Example 02：
- read.c

    #include <stdio.h>
    #include "student.h"
    void read(FILE *fp,int index);
    int main(){
        FILE *fp = fopen("student.data","r");
        if(fp){
            fseek(fp,0L,SEEK_END);
            long size = ftell(fp);
            int number = size / sizeof(Student);
            int index = 0;
            printf("有%d个数据，你要看第几个：",number);
            scanf("%d",&index);
            read(fp,index-1);
            fclose(fp);
        }
        return 0;
    }
    void read(FILE *fp,int index){
        fseek(fp,index * sizeof(Student),SEEK_SET);
        Student stu;
        if(fread(&stu,sizeof(Student),1,fp) == 1){
            printf("第%d个学生：",index+1);
            printf("\t姓名：%s\n",stu.name);
            printf("\t性别：");
            switch(stu.gender) {
                case 0:printf("男\n");break;
                case 1:printf("女\n");break;
                case 2:printf("其他\n");break;
            }
            printf("\t年龄：%d\n",stu.age);
        }
    }