The C ++ standard file stream reads the file in stringtoken units and refresh and rewrite all

Use an array to save the intermediate variable. After modification, write the variable again.

 

# Include "stdafx. H"
# Include <cstdlib>
// Write a program that makes a virtual get system.

// Write a program that saves and alters student records saved to and from a file.
// A student shoshould consist of a first name, last name, age, GPA (double), and units completed (INT ).
// Write a program that evaluates Student Information Based on teacher input (of grades and units completed ).
// Students must be defined in a class.

// Teacher input: What shocould be input is a numerical grade as well as units entered for a class.
// Professors must also be part of a class. Each pointer SOR, contains: a first name, last name, age, password.

// Note: Both Student and pointer sor records must be saved to files.

# Include <cmath> // header file for math functions
# Include <iostream> // header file for all basics ie class, Cin, cout, void
Using namespace STD; // standard namespace helps compiler translate Program
# Include <fstream>
# Include <string>
# Include <iomanip>

Class student // class declaration
{

Public: // encapsulating via data hiding; makes sure no external function can touch this data
Int units; // any variable in this case scores
Double GPA;

String firstname;
String lastname;

Int age;

};

Class aggregsor
{
PRIVATE:

String firstname;
String lastname;

Int age;
String password;


Public:

Cursor sor (string FN, string ln, int A, string PW)
{
This-> firstname = FN;
This-> lastname = ln;
This-> age =;
This-> Password = pw;
}

String GetPassword ()
{
Return this-> password;
}


};

Int main ()
{
Partition sor * Pr = new partition sor ("Lee", "Joel", 30, "password ");

String PW = "";
// While (PW. Compare (pr-> GetPassword ())! = 0)
{
// Cout <"this is another sor" <"Joel Lee, 30 years old," <"Please enter your password :";
// CIN> PW;
}

Cout <"this is another sor" <"Joel Lee, 30 years old, no password" <Endl;

Ifstream indata; // For the file

Indata. Clear ();

String filename;
Filename = "studentrecord.txt ";

Int I = 0;
Int line = 0;
String temp_word;
Indata. Open (filename. c_str ());
// 1. Get the line of the file
While (indata. Good ())
{
If (I! = 0 & I % 4 = 0)
{
Line ++;

}
Indata> temp_word;
I ++;
}

Indata. Close ();

// 2. Make the temporary memort to store

Student * Stu = new student [Line];

Ifstream indata2; // For the file
Indata2.clear ();

Indata2.open (filename. c_str ());

I = 0;
Int nowline = 0;

// 3. Output and change the scores
While (indata2.good () & nowline <line)
{
Int U;
Double G;

If (I = 0)
{

Indata2> STU [nowline]. firstname;
Cout <STU [nowline]. firstname;

}
Else if (I = 1)
{

Indata2> STU [nowline]. lastname;
Cout <STU [nowline]. lastname;

}
Else if (I = 2)
{

Indata2> STU [nowline]. Units;
Cout <STU [nowline]. Units;
}

Else if (I = 3)
{

Indata2> STU [nowline]. GPA;
Cout <STU [nowline]. GPA;
}
I ++;
If (I = 4)
{
Cout <Endl;
Cout <"input the new unit :";
Cin> U;
STU [nowline]. Units = u;
Cout <"input the new GPA :";
Cin> G;
STU [nowline]. GPA = g;
Nowline ++;
I = 0;

}

Cout <"";

}
Indata2.close ();

// 4. Write the new scores to file

Ofstream F1;
// String fileout = "tabular.txt ";
F1.open (filename. c_str ());
If (! F1) return 1;
For (INT I = 0; I <line; I ++)
{
F1 <STU [I]. firstname <"";
F1 <STU [I]. lastname <"";
F1 <STU [I]. Units <"";
F1 <setprecision (2) <STU [I]. GPA <"<Endl;
}

F1.close ();

// End
Cout <Endl;

System ("pause ");

Return 0;
}

File Format:

 

Paul Lee 1 1
Jack wa 1 1
Joel Joe 1 1