本文實例為大家分享了C語言就餐管理系統的具體代碼，供大家參考，具體內容如下

#include<stdio.h>#include<string.h>#include<stdlib.h>#define N 20#define M 20struct 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 請輸入您要選擇的操作序號："); 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("輸入錯誤！/n "); } }}void menu(){printf(" **************************** 食堂就餐餐費管理系統************************ "); printf("/n       1 添加學生信息"); printf("/n       2 顯示學生信息"); printf("/n       3 添加食譜信息"); printf("/n       4 按學號添加餐費"); printf("/n       5 查詢某日食譜"); printf("/n       6 刪除學生信息"); printf("/n       7 修改學生信息"); printf("/n       8 退出");} void reads(struct student stu[N],int *n) //讀取學生信息文件{ FILE *fp; int i=0; if((fp=fopen("studenttt.txt","rb"))==NULL) { printf("文件打開失敗！/n"); return; } else { *n=getw(fp); for(i=0;i<*n;i++)  fread(&stu[i],sizeof(struct student),1,fp); } fclose(fp);}void addstudent() //添加學生信息{FILE *fp; int n,i,j; struct student stu; if((fp=fopen("studenttt.txt","rb+"))!=NULL) //讀寫 {j=getw(fp); rewind(fp); printf("請輸入要添加的學生數量：");  scanf("%d",&n); putw(j+n,fp); fseek(fp,0L,2); //移動位置指針 for(i=1;i<=n;i++) { printf("/n請輸入第%d個學生的學號和姓名：/n",i);  scanf("%s%s",stu.num,stu.name);  printf("/n請輸入第%d個學生的總餐費：/n",i);  scanf("%f",&stu.dietfee);  fwrite(&stu,sizeof(struct student),1,fp);  //向文件寫一組數據 } } else //文件不存在時，新建一個文件，并將數據寫入該文件 {  if((fp=fopen("studenttt.txt","wb"))!=NULL)  //只寫 { printf("請輸入要添加的學生數量：");   scanf("%d",&n);  putw(n,fp); for(i=1;i<=n;i++) { printf("/n請輸入第%d個學生的學號和姓名：/n",i);  scanf("%s%s",stu.num,stu.name);  printf("/n請輸入第%d個學生的總餐費：/n",i);  scanf("%f",&stu.dietfee);  fwrite(&stu,sizeof(struct student),1,fp); } } }  fclose(fp);}void readss(struct diet die[M],int *t) //讀取食譜文件{ FILE *fp2; int i=0; if((fp2=fopen("diet.txt","rb"))==NULL) { printf("文件打開失敗！/n"); return; } else { *t=getw(fp2); for(i=0;i<*t;i++)  fread(&die[i],sizeof(struct diet),1,fp2); } fclose(fp2);}void adddiet() //添加食譜信息{FILE *fp2; int n,i,j; struct diet die; if((fp2=fopen("diet.txt","rb+"))!=NULL) {j=getw(fp2); rewind(fp2); printf("請輸入要添加的食譜數量：");  scanf("%d",&n); putw(j+n,fp2); fseek(fp2,0L,2); for(i=1;i<=n;i++) { printf("/n請輸入第%d個食譜的日期：/n",i);  scanf("%s",die.date);  printf("/n請輸入第%d個食譜的早餐和費用，午餐和費用，晚餐和費用：/n",i);  scanf("%s%s%s",&die.breakfast,&die.lunch,&die.supper);  fwrite(&die,sizeof(struct diet),1,fp2); } }        else   //文件不存在時，新建一個文件，并將數據寫入該文件         {  if((fp2=fopen("diet.txt","wb"))!=NULL) { printf("請輸入要添加的食譜數量：");   scanf("%d",&n);  putw(n,fp2); for(i=1;i<=n;i++) { printf("/n請輸入第%d個食譜的日期：/n",i);   scanf("%s",die.date);   printf("/n請輸入第%d個食譜的早餐和費用，午餐和費用，晚餐和費用：/n",i);   scanf("%s%s%s",&die.breakfast,&die.lunch,&die.supper);   fwrite(&die,sizeof(struct diet),1,fp2); } } }  fclose(fp2);}void show()   //顯示學生信息{struct student stu[N]; int i,n; reads(stu,&n); if(n==0) return; for(i=0;i<n;i++) printf("/n 學號： %s姓名: %s餐費：%f/n",stu[i].num,stu[i].name,stu[i].dietfee);}void addfee()  //添加學生餐費{struct student stu[N],temp; int n,i; float g; FILE *fp; printf("/n請輸入要增加餐費學生學號："); 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("無此學生信息!/n"); return; } printf("/n請輸入增加該學生的餐費數：/n"); scanf("%f",&g); stu[i].dietfee+=g; /*strcpy(stu[i].dietfee,temp.dietfee);*/ if((fp=fopen("studenttt.txt","wb"))==NULL) {printf("打開文件失敗！"); return; } putw(n,fp); for(i=0;i<n;i++) fwrite(&stu[i],sizeof(struct student),1,fp); fclose(fp);}void query()   //查詢某日食譜信息 { struct diet die[M]; char date[20]; int i,n; readss(die,&n); printf("/n請輸入待查詢食譜日期：/n"); scanf("%s",date); for(i=0;i<n;i++) if(strcmp(date,die[i].date)==0) break; if(i>=n) {printf("沒有找到該日食譜信息！/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() //刪除學生信息{ struct student stu[N]; struct student stu2[N]; int i,n,m,s; FILE *fp;  int j; char num2[20]; printf("請輸入要刪除的學生學號：");  scanf("%s",&num2); reads(stu,&n); if(n==0) {  printf("沒有學生可以刪除！");  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("該學生不存在！");  return; } else{      if((fp=fopen("studenttt.txt","wb"))!=NULL)  //只寫 {  putw(m,fp); for(j=0;j<m;j++) {  fwrite(&stu2[j],sizeof(struct student),1,fp); } }  fclose(fp);   printf("刪除成功！/n");  }}void midefy(){ //按照學號修改 struct student stu[N]; struct student stu2[N]; int i,n,m,s; FILE *fp;  int j; char num2[20]; printf("請輸入要修改的學生學號：");  scanf("%s",&num2); reads(stu,&n); if(n==0) {  printf("沒有學生可以修改！/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你要修改學生的學號為%s：/n",stu[i].num);   printf("/n請輸入該學生的姓名:");     scanf("%s",stu2[m].name);  printf("/n請輸入該學生的總餐費：/n",i);  scanf("%f",&stu2[m].dietfee);    continue;   } } if(s==0){  printf("該學生不存在！/n");  return; } else{      if((fp=fopen("studenttt.txt","wb"))!=NULL)  //只寫 {  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");  }}