本文实例为大家分享了C语言就餐管理系统的具体代码，供大家参考，具体内容如下

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#define N 20
#define M 20
struct student
{char num[20];
 char name[10];
 float dietfee;
 
};
struct diet
{char date[20];
char breakfast[100];
char lunch[100];
char supper[100];
};
void menu();
void reads();
void readss();
void addstudent();
void adddiet();
void addfee();
void query();
void show();
void dele();
void midefy();
void main()

{
 int n;
 while(1)
 { 
 menu();
 printf("\n 请输入您要选择的操作序号：");
 scanf("%d",&n);
 switch(n)
 {case 1: addstudent();break;
 case 2: show();break;
 case 3: adddiet();break;
 case 4: addfee();break;
 case 5: query();break;
 case 6: dele();break;
 case 7: midefy();break;
 case 8: exit(0);
 default: printf("输入错误！\n ");
 }
 }
}
void menu()
{printf(" **************************** 食堂就餐餐费管理系统************************ ");
 printf("\n       1 添加学生信息");
 printf("\n       2 显示学生信息");
 printf("\n       3 添加食谱信息");
 printf("\n       4 按学号添加餐费");
 printf("\n       5 查询某日食谱");
 printf("\n       6 删除学生信息");
 printf("\n       7 修改学生信息");
 printf("\n       8 退出");
}
 void reads(struct student stu[N],int *n) //读取学生信息文件
{
 FILE *fp;
 int i=0;
 if((fp=fopen("studenttt.txt","rb"))==NULL)
 { printf("文件打开失败！\n");
 return;
 }
 else
 {
 *n=getw(fp);
 for(i=0;i<*n;i++)
  fread(&stu[i],sizeof(struct student),1,fp);
 }
 fclose(fp);
}
void addstudent() //添加学生信息
{FILE *fp;
 int n,i,j;
 struct student stu;
 if((fp=fopen("studenttt.txt","rb+"))!=NULL) //读写
 {j=getw(fp);
 rewind(fp);
 printf("请输入要添加的学生数量："); 
 scanf("%d",&n);
 putw(j+n,fp);
 fseek(fp,0L,2); //移动位置指针
 for(i=1;i<=n;i++)
 { printf("\n请输入第%d个学生的学号和姓名：\n",i);
  scanf("%s%s",stu.num,stu.name);
  printf("\n请输入第%d个学生的总餐费：\n",i);
  scanf("%f",&stu.dietfee);
  fwrite(&stu,sizeof(struct student),1,fp);  //向文件写一组数据
 }
 }
 else //文件不存在时，新建一个文件，并将数据写入该文件
 { 
 if((fp=fopen("studenttt.txt","wb"))!=NULL)  //只写
 {
 printf("请输入要添加的学生数量："); 
  scanf("%d",&n);
  putw(n,fp);
 for(i=1;i<=n;i++)
 { printf("\n请输入第%d个学生的学号和姓名：\n",i);
  scanf("%s%s",stu.num,stu.name);
  printf("\n请输入第%d个学生的总餐费：\n",i);
  scanf("%f",&stu.dietfee);
  fwrite(&stu,sizeof(struct student),1,fp);
 }
 }
 } 
 fclose(fp);
}
void readss(struct diet die[M],int *t) //读取食谱文件
{
 FILE *fp2;
 int i=0;
 if((fp2=fopen("diet.txt","rb"))==NULL)
 { printf("文件打开失败！\n");
 return;
 }
 else
 {
 *t=getw(fp2);
 for(i=0;i<*t;i++)
  fread(&die[i],sizeof(struct diet),1,fp2);
 }
 fclose(fp2);
}
void adddiet() //添加食谱信息
{FILE *fp2;
 int n,i,j;
 struct diet die;
 if((fp2=fopen("diet.txt","rb+"))!=NULL)
 {j=getw(fp2);
 rewind(fp2);
 printf("请输入要添加的食谱数量："); 
 scanf("%d",&n);
 putw(j+n,fp2);
 fseek(fp2,0L,2);
 for(i=1;i<=n;i++)
 { printf("\n请输入第%d个食谱的日期：\n",i);
  scanf("%s",die.date);
  printf("\n请输入第%d个食谱的早餐和费用，午餐和费用，晚餐和费用：\n",i);
  scanf("%s%s%s",&die.breakfast,&die.lunch,&die.supper);
  fwrite(&die,sizeof(struct diet),1,fp2);
 }
 }       
 else   //文件不存在时，新建一个文件，并将数据写入该文件        
 { 
 if((fp2=fopen("diet.txt","wb"))!=NULL)
 {
 printf("请输入要添加的食谱数量："); 
  scanf("%d",&n);
  putw(n,fp2);
 for(i=1;i<=n;i++)
 { printf("\n请输入第%d个食谱的日期：\n",i);
   scanf("%s",die.date);
   printf("\n请输入第%d个食谱的早餐和费用，午餐和费用，晚餐和费用：\n",i);
   scanf("%s%s%s",&die.breakfast,&die.lunch,&die.supper);
   fwrite(&die,sizeof(struct diet),1,fp2);
 }
 }
 } 
 fclose(fp2);
}
void show()   //显示学生信息
{struct student stu[N];
 int i,n;
 reads(stu,&n);
 if(n==0)
 return;
 for(i=0;i<n;i++)
 printf("\n 学号： %s姓名: %s餐费：%f\n",stu[i].num,stu[i].name,stu[i].dietfee);
}
void addfee()  //添加学生餐费
{struct student stu[N],temp;
 int n,i;
 float g;
 FILE *fp;
 printf("\n请输入要增加餐费学生学号：");
 scanf("%s",temp.num);
 reads(stu,&n);
 for(i=0;i<n;i++)
 if(strcmp(temp.num,stu[i].num)==0)
 break;
 if(i>=n)
 {printf("无此学生信息!\n");
 return;
 }
 printf("\n请输入增加该学生的餐费数：\n");
 scanf("%f",&g);
 stu[i].dietfee+=g;
 /*strcpy(stu[i].dietfee,temp.dietfee);*/
 if((fp=fopen("studenttt.txt","wb"))==NULL)
 {printf("打开文件失败！");
 return;
 }
 putw(n,fp);
 for(i=0;i<n;i++)
 fwrite(&stu[i],sizeof(struct student),1,fp);
 fclose(fp);
}

void query()   //查询某日食谱信息 
{
 struct diet die[M];
 char date[20];
 int i,n;
 readss(die,&n);
 printf("\n请输入待查询食谱日期：\n");
 scanf("%s",date);
 for(i=0;i<n;i++)
 if(strcmp(date,die[i].date)==0) break;
 if(i>=n)
 {printf("没有找到该日食谱信息！\n");
 return;
 }
 else
  printf("\n 日期：%s早餐%s：午餐：%s晚餐：%s\n",die[i].date,die[i].breakfast,die[i].lunch,die[i].supper);
 }
 
void dele() //删除学生信息
{
 struct student stu[N];
 struct student stu2[N];
 int i,n,m,s;
 FILE *fp;
 
 int j;
 char num2[20];
 printf("请输入要删除的学生学号："); 
 scanf("%s",&num2);
 reads(stu,&n);
 if(n==0)
 {
  printf("没有学生可以删除！"); 
 return;
 }
 for(m=0,i=0;i<n;i++){

     

 if(strcmp(stu[i].num,num2)!=0)
 { 
  
  strcpy(stu2[m].num,stu[i].num);
  strcpy(stu2[m].name,stu[i].name);
  stu2[m].dietfee =stu[i].dietfee;
  s=1;
  m++;
  
 }else{

   continue; 
 }
 }
 if(s==0){
 
 printf("该学生不存在！"); 
 return;

 } else{
   
   if((fp=fopen("studenttt.txt","wb"))!=NULL)  //只写
 {
 
 putw(m,fp);
 for(j=0;j<m;j++)
 { 

 fwrite(&stu2[j],sizeof(struct student),1,fp);
 }
 }

  fclose(fp);
  
 printf("删除成功！\n"); 
 }
}
void midefy(){ //按照学号修改
 struct student stu[N];
 struct student stu2[N];
 int i,n,m,s;
 FILE *fp;
 
 int j;
 char num2[20];
 printf("请输入要修改的学生学号："); 
 scanf("%s",&num2);
 reads(stu,&n);
 if(n==0)
 {
  printf("没有学生可以修改！\n"); 
 return;
 }
 for(m=0,i=0;i<n;i++,m++){

     

 if(strcmp(stu[i].num,num2)!=0)
 { 
  
  strcpy(stu2[m].num,stu[i].num);
  strcpy(stu2[m].name,stu[i].name);
  stu2[m].dietfee =stu[i].dietfee;
 
 
  
 }else{ 
   s=1;
   strcpy(stu2[m].num,stu[i].num);
     printf("\n你要修改学生的学号为%s：\n",stu[i].num);
   printf("\n请输入该学生的姓名:");
     scanf("%s",stu2[m].name);
  printf("\n请输入该学生的总餐费：\n",i);
  scanf("%f",&stu2[m].dietfee);
  
  continue;
  
 }
 }
 if(s==0){
 
 printf("该学生不存在！\n"); 
 return;

 } else{
   
   if((fp=fopen("studenttt.txt","wb"))!=NULL)  //只写
 {
 
 putw(m,fp);
 for(j=0;j<m;j++)
 { 

 fwrite(&stu2[j],sizeof(struct student),1,fp);
 }
 }

  fclose(fp);
  
 printf("修改成功！\n"); 
 }
}