C語言 文件I/O：實現結構體數據 存儲到文件和從文件讀取

這是一個初步試驗！是爲了下一步的創建班級學生管理系統做準備

效果：

ClassInfo.h源碼

#define MAX_STUDENT 50 //班級最大學生人數
#define MAX_NAME_SPACE 30 //學生名稱最大空間
#define MAX_CLASS_NAME_SPACE 20 //班級名稱最大空間
#define MAX_ID_SPACE 20 //班級ID最大空間

typedef struct student_
{
        char classId[MAX_ID_SPACE];
        char name[MAX_NAME_SPACE];
        int age;
        int id;
        struct student_ * nextStu;
}Student,*PStudent;

typedef struct class_
{
        char className[MAX_CLASS_NAME_SPACE];
        char classId[MAX_ID_SPACE];
        struct class_ * next_Class;
        PStudent firstStu;
}Class,*PClass;

void viewClass(PClass rootClass)
{
    PClass tc = rootClass;
    if(tc==NULL)
    {
        printf("未創建任何班級，無法遍歷");
        return;
    }
    system("cls");
    while(tc!=NULL)
    {
        printf("------------------------------------\n");
        printf("班級ID：%s\n",(tc->classId));
        printf("班級名稱：%s\n",(tc->className));
        tc=tc->next_Class;
    }
    printf("------------------------------------\n");
    return;
}

main.c源碼

#include <stdio.h>
#include <stdlib.h>
#include <sys/fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include "Class_Info.h"
#include <string.h>

int main()
{
    //僅僅測試核心操作：存儲和讀取數據包
    PClass newclass = (PClass)calloc(1,sizeof(Class));
    printf("請輸入班級編號(如:201309001)：");
    gets(newclass->classId);
    printf("請輸入班級名稱(如:13軟件2班)：");
    gets(newclass->className);
    newclass->firstStu=NULL;
    newclass->next_Class = NULL;

    //查看結構體（對象）的內容
    viewClass(newclass);

    FILE * fp;

    if((fp = fopen("./Class.dat","r+"))==NULL)
    {
        printf("找不到Class.dat文件!\n");

        if((fp = fopen("./Class.dat","w+"))==NULL)
        {

            perror("fopen failed! ");
            return -1;
        }
        printf("已自動生成Class.dat\n");
    }

    //寫入鏈表的數據到文件 大小+數據
    int slen = strlen(newclass->classId);
    fwrite(&slen,sizeof(int),1,fp);
    fwrite(newclass->classId,slen,1,fp);

    slen = strlen(newclass->className);
    fwrite(&slen,sizeof(int),1,fp);
    fwrite(newclass->className,slen,1,fp);

    fclose(fp);
    getchar();

    printf("讀取文件數據到鏈表！\n");


    //創建新的結構體對象
    PClass readClass = (PClass)calloc(1,sizeof(Class));
    readClass->firstStu=NULL;
    readClass->next_Class=NULL;
    slen=0;

    if((fp = fopen("./Class.dat","r+"))==NULL)
    {
        perror("找不到Class.dat文件!");
        return -1;
    }

    //讀取Class.dat中的數據 格式 ： 數據大小+數據
    fread(&slen,sizeof(int),1,fp);
    printf("\n第一個數據大小：%d\n",slen);
    fread(readClass->classId,slen,1,fp);
    printf("第一個數據內容：%s\n",readClass->classId);

    fread(&slen,sizeof(int),1,fp);
    printf("第二個數據大小：%d\n",slen);
    fread(readClass->className,slen,1,fp);
    printf("第二個數據內容：%s\n",readClass->className);

    fclose(fp);

    //釋放鏈表頭的指針（因爲當前就一個數據）
    free(newclass);
    free(readClass);

    getchar();

    return 0;
}