How to execute file related cpp program in CodeProject IDE

Hello everyone,
I am trying to execute the file operation program in COODEBLOCKS editor. The program executes. The search function and display functions are going infinite loop OR something is wrong.
Could you please let me know what is wrong.
Thanks

#include<stdlib.h>
#include<iostream>
#include<fstream>
#include<string.h>
using namespace std;
class student
{
	public: char name[10];
		char usn[10];
		char age[5];
		char sem[5];
		char branch[5];
		char buffer[45];
};
fstream file;
student s;
void pack()
{
int k,n;
printf("how many records\n");
	scanf("%d",&n);
	for(k=0;k<n;k++)
	{
cout<<"\nenter the student name = ";
	cin>>s.name;
	cout<<"\nenter the usn = ";
	cin>>s.usn;
	cout<<"\nenter the age = ";
	cin>>s.age;
	cout<<"\nenter the sem = ";
	cin>>s.sem;
	cout<<"\nenter the branch = ";
	cin>>s.branch;
	strcpy(s.buffer,s.name);
	strcat(s.buffer,"|");
	strcat(s.buffer,s.usn);
	strcat(s.buffer,"|");
	strcat(s.buffer,s.age);
	strcat(s.buffer,"|");
	strcat(s.buffer,s.sem);
	strcat(s.buffer,"|");
	strcat(s.buffer,s.branch);
	int count=strlen(s.buffer);
for(int k=0;k<45-count;k++)
		strcat(s.buffer,"!");
	strcat(s.buffer,"\n");
file<<s.buffer;  
}
	file.close();
}
void writerecord()
{
	file.open("p2.txt",ios::out);
	if(!file)
	{
		cout<<"cannot open the file in out mode";
		exit(1);
	}
pack();
	
}
void unpack()
{
		file.getline(s.name,10,'|');
		file.getline(s.usn,10,'|');
		file.getline(s.age,5,'|');
		file.getline(s.sem,5,'|');
		file.getline(s.branch,5,'!');
}
void search()
{
	char usn[10];
	char extra[45];
	file.open("p2.txt",ios::in);
	if(!file)
	{
		cout<<"\nunable to open the file in read mode";
		exit(0);
	}
	cout<<"\nenter the record's usn you want to search = ";
	cin>>usn;
	while(!file.eof())
	{
		unpack();
		file.getline(extra,45,'\n');
		if(strcmp(s.usn,usn)==0)
		{
			cout<<"\nrecord found";
			cout<<"\n"<<s.name<<"\t"<<s.usn<<"\t"<<s.age<<"\t"<<s.sem<<"\t"<<s.branch;
			file.close();
			
			return;
		}
	}
	cout<<"\nrecord not found";
	file.close();
	
}
void displayFile()
{
	int i;
	char extra[45];
	file.open("p2.txt",ios::in);
	if(!file)
{
		cout<<"\ncannot open the file in read mode";
		exit(1);
	}
	i=0;
	cout<<"\n\nNAME\t\tUSN\t\tAGE\t\tSEM\t\tBRANCH\n";
	cout<<"----\t\t---\t\t---\t\t---\t\t------\n";
	while(!file.eof())
	{
		unpack();
		file.getline(extra,45,'\n');
		cout<<"\n"<<s.name<<"\t"<<s.usn<<"\t"<<s.age<<"\t"<<s.sem<<"\t"<<s.branch<<"\n";
	}
	file.close();
}
void modify()
{
	char usn[10];
	char buffer[45];
	char extra[45];
	int i;
	int j;
	student s[20];
	file.open("p2.txt",ios::in);
	if(!file)
	{
		cout<<"\nunable to open the file in input mode";
		exit(1);
	}
	cout<<"\nenter the usn of the record to be modified\n";
	cin>>usn;
	cout<<"\n";
	i=0;
	while(!file.eof())
	{
		file.getline(s[i].name,10,'|');
		file.getline(s[i].usn,10,'|');
		file.getline(s[i].age,5,'|');
		file.getline(s[i].sem,5,'|');
		file.getline(s[i].branch,5,'!');
		file.getline(extra,45,'\n');
		i++;
	}
	i--;
	for(j=0;j<i;j++)
	{
		if(strcmp(usn,s[j].usn)==0)
		{
			cout<<"\nthe old values of the record with usn"<<usn<<"are";
			cout<<"\n\nNAME\t\tUSN\t\tAGE\t\tSEM\t\tBRANCH\n";
			cout<<"----\t\t---\t\t---\t\t---\t\t------\n";
	cout<<s[j].name<<"\t"<<s[j].usn<<"\t"<<s[j].age<<"\t"<<s[j].sem<<"\t"<<s[j].branch<<"\n";
			cout<<"\n\nenter the new values\n";
			cout<<"\nname = ";
			cin>>s[j].name;
			cout<<"\nusn = ";
			cin>>s[j].usn;
			cout<<"\nage = ";
			cin>>s[j].age;
			cout<<"\nsem = ";
			cin>>s[j].sem;
			cout<<"\nbranch = ";
			cin>>s[j].branch;
			break;
		}
	}
	if(j==i)
	{
		cout<<"\nthe record with usn "<<usn<<"is not present ";
		return;
	}
	file.close();
	file.open("p2.txt",ios::out);
	if(!file)
	{
		cout<<"\nunable to open the file in output mode";
		return;
	}
	for(j=0;j<i;j++)
	{
strcpy(buffer,s[j].name);
		strcat(buffer,"|");
		strcat(buffer,s[j].usn);
		strcat(buffer,"|");
		strcat(buffer,s[j].age);
		strcat(buffer,"|");
		strcat(buffer,s[j].sem);
		strcat(buffer,"|");
		strcat(buffer,s[j].branch);
		int count=strlen(buffer);
		for(int k=0;k<45-count;k++)
			strcat(buffer,"!");
		strcat(buffer,"\n");
		file<<buffer;
	}
	file.close();
}
int main()
{
	int choice;
	while(1)
	{
		cout<<"\n 0 : exit \n 1 : write to file\n 2 : display the file\n 3 : modify the file\n 4 : search \n\n enter the choice : ";
		cin>>choice;
		switch(choice)
		{
			case 1: writerecord();
				break;
			case 2: displayFile();
				break;
			case 3: modify();
				break;
			case 4: search();
				break;
			case 0: exit(0);
			default:cout<<"\ninvalid input...";
				break;
		}
	}
return 0;
}