#include <iostream>
#include <fstream>
using namespace std;

int main()
{
	fstream.dat;
	dat.open("text1.txt",ios::out);
	dat << "Please work" << endl;
	dat << "work damn you!!!!" << endl;
	int i=150;
	dat << i << endl;
	dat.close();
	return 1;
}

#include <iostream>
#include <fstream>
using namespace std;

int main()
{
	char temp[80]; //what's this variable's function?
	fstream dat;
	dat.open("text1.txt",ios::in);
	if(!dat)
	{
		cout << "File does not exist!" << endl;
	}
	else
	{
		while(1)
		{
			dat.getline(temp,sizeof(temp),'\n');
			if(dat.eof()) break;
			cout << temp << endl;
		};
	};
	dat.close();
	return 1;
}

ifstream dat ( "text1.txt" );

while ( dat.getline ( temp, sizeof temp ) )
  cout<< temp <<'\n';

#include <iostream>
#include <fstream>
using namespace std;


void input(char *array)
{
        cin.getline(array, 150);
	if(cin.gcount()==1)
		cin.getline(array,150);
};


struct tstudent
{
	int number;
	char name[30];
	int degree;
};


void create_file(tstudent student)
{
        char FileName[20];
	cout << "Enter the name of your new file:" << endl;
	cin >> FileName;
	fstream dat ("data.txt",ios::out | ios::binary);
};


void input_data(tstudent student)
{
	fstream dat;
	char more='y';
	while((more=='y')||(more=='y'))
	{
		cout << "Student number: "; cin >> student.number;
		cout << "Student's name: "; input(student.name);
		cout << "College degree: "; cin >> student.degree;
		dat.write ((char *) &student,sizeof(student));
		cout <<"Wish to input more data (y/n) ? ";
		cin >> more;
	};
	dat.close();
};


void output_all_students(tstudent student)
{
	fstream dat ("data.txt",ios::in | ios::binary);
	while (1){
		dat.read ((char *) &student,sizeof(student));
		if (dat.eof()) break;
		cout << "Student number : " << student.number << endl;
		cout << "Student's name: " << student.name << endl;
		cout << "College degree: " << student.degree << endl;
	};
	dat.close(); 
};

void output_specific_student(tstudent student, int nr)
{
	int counter=0;
	dat.open("data.txt",ios::in | ios::binary);
	while (1){
		dat.read((char *) &student,sizeof(student));
		if (dat.eof()) break;
		if (student.number==nr){
			cout << "Student number: " << student.number << endl;
			cout << "Student's name: " << student.name << endl;
			cout << "College degree: " << student.degree << endl;
			counter++;
		}
	}
	if (counter==0)
		cout << "Student with number  " << number << " doesn't exist."<<endl;
	dat.close();
};


	
void main()
{
	int nr;
	tstudent student;
	int choice;
	do{
		cout << "1. Create file" << endl;
		cout << "2. Input data into file" << endl;
		cout << "3. Output all the data from the file" << endl;
		cout << "4. Output data for specific student" << endl;
		cout << "5. Exit the program" << endl;
		cin >> choice;
		
		switch(choice)
		{
		case 1:	create_file(student); break; 
		case 2:	input_data(student); break;
		case 3:	output_all_students(student); break;
		case 4:	cout << "Student's number:"; cin >> nr;
		            output_specific_student(student, nr); break;
		case 5: exit(0);
		};
	}while(choice!=5);
}

	tstudent student; Declaration, not set to anything (initialized).
	int choice;
	do{
		cout << "1. Create file" << endl;
		cout << "2. Input data into file" << endl;
		cout << "3. Output all the data from the file" << endl;
		cout << "4. Output data for specific student" << endl;
		cout << "5. Exit the program" << endl;
		cin >> choice;

No initialization anywhere here in the red, either....
		
		switch(choice)
		{
		case 1:	create_file(student); break; 
so....not initialized here either, unless you have 
a dead chicken and some expertise with voodoo.