[英]Student Management System C++
我在C ++中有用于学生管理系统的程序,一切正常,除了一个地方,我尝试根据学生的卷号删除该学生。 它应该做什么:在询问卷号之后搜索记录并将其删除它在做什么:它删除所有其他与该卷号不匹配的记录
这是我的代码:
#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <conio.h>
#include <iomanip>
using namespace std;
int main() {
FILE *fp, *ft;
char another, choice;
struct student {
char first_name[50], last_name[50];
int roll_num; //new code added
char course[100];
int section;
};
struct student e;
char xfirst_name[50], xlast_name[50];
int xroll_num ; // new code added
long int recsize;
fp=fopen("users.txt","rb+");
if (fp == NULL) {
fp = fopen("users.txt","wb+");
if (fp==NULL)
{
puts("Cannot open file");
return 0;
}
}
recsize = sizeof(e);
while(1) {
system("cls");
cout << "\t\t====== STUDENT INFORMATION SYSTEM ======";
cout <<"\n\n ";
cout << "\n\n";
cout<<" \n\t\t\t======================";
cout << "\n \t\t\t 1. Add Records";
cout << "\n \t\t\t 2. List Records";
cout << "\n \t\t\t 3. Modify Records";
cout << "\n \t\t\t 4. Delete Records";
cout << "\n \t\t\t 5. Exit Program";
cout<<" \n\t\t\t======================";
cout << "\n\n";
cout << "\t\t\t Select Your Choice ::";
fflush(stdin);
choice = _getche();
switch(choice)
{
case '1' :
fseek(fp,0,SEEK_END);
another ='Y';
while(another == 'Y' || another == 'y')
{
system("cls");
cout << "Enter the First Name : ";
cin >> e.first_name;
cout << "Enter the Last Name : ";
cin >> e.last_name;
cout << "Enter the Course : ";
cin >> e.course;
cout << "Enter the Section : ";
cin >> e.section;
cout << "Enter the roll number :";
cin >> e.roll_num;
fwrite(&e,recsize,1,fp);
cout << "\n Add Another Record (Y/N) ";
fflush(stdin);
another = getchar();
}
break;
case '2':
system("cls");
rewind(fp);
cout << "=== View the Records in the Database ===";
cout << "\n";
while (fread(&e,recsize,1,fp) == 1){
cout << "\n";
cout <<"\nName :: " <<e.first_name <<" "<<e.last_name;
//cout << "\n";
cout <<"\nRoll Number :: " << e.roll_num ;
cout <<"\nCourse :: " <<e.course ;
cout <<"\nSection :: "<<e.section;
}
cout << "\n\n";
system("pause");
break;
case '3' :
system("cls");
another = 'Y';
while (another == 'Y'|| another == 'y')
{
// cout << "\n Enter the last name of the student : ";
cout << "\n Enter the Roll number of the student : ";
cin >> xroll_num;
rewind(fp);
while (fread(&e,recsize,1,fp) == 1)
{
//if (strcmp(e.last_name,xlast_name) == 0)
if(e.roll_num == xroll_num )
{
cout << "Enter the new Firt Name : ";
cin >> e.first_name;
cout << "Enter the new Last Name : ";
cin >> e.last_name;
cout << "Enter the new Roll Number : ";
cin >> e.roll_num;
cout << "Enter the new Course : ";
cin >> e.course;
cout << "Enter the new Section : ";
cin >> e.section;
fseek(fp, - recsize, SEEK_CUR);
fwrite(&e,recsize,1,fp);
break;
}
else
cout<<"record not found";
}
cout << "\n Modify Another Record (Y/N) ";
fflush(stdin);
another = getchar();
}
break;
case '4':
system("cls");
another = 'Y';
while (another == 'Y'|| another == 'y')
{
// cout << "\n Enter the last name of the student to delete : ";
cout <<"\n Enter the roll number of the student to delete : ";
cin >> xroll_num;
ft = fopen("temp.dat", "wb");
rewind(fp);
while (fread (&e, recsize,1,fp) == 1)
// if (strcmp(e.last_name,xlast_name) != 0)
if(e.roll_num == xroll_num )
{
fwrite(&e,recsize,1,ft);
}
fclose(fp);
fclose(ft);
remove("users.txt");
rename("temp.dat","users.txt");
fp=fopen("users.txt","rb+");
cout << "\n Delete Another Record (Y/N) ";
fflush(stdin);
another = getchar();
}
break;
case '5':
fclose(fp);
cout << "\n\n";
cout << "\t\t THANK YOU FOR USING THIS SOFTWARE";
cout << "\n\n";
exit(0);
}
}
system("pause");
return 0;
}
它删除所有其他与该卷号不匹配的记录
好吧,您只需将与卷号匹配的记录写入临时文件,然后使用该文件覆盖users.txt
文件
if (e.roll_num == xroll_num) {
fwrite(&e, recsize, 1, ft);
}
我想你真正想做的是
if (e.roll_num != xroll_num) {
fwrite(&e, recsize, 1, ft);
}
您可能应该阅读一个不错的C ++ I / O教程,因为您的代码主要是C。考虑将您的student
结构写为简单文本,而不是将其批发到文件中。
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