C++ GPA Calculator

// GPA Calculator.cpp : Defines the entry point for the console application. 

#include "stdafx.h"            //header file specific for visual studio only...!!!!
#include <iostream>
using namespace std;
#define MAX 7
void input(int data[][2], char sub[][20], char g[][3], int nn);
void process(int data[][2], float gpa[], int nn, float& res,int& crh);
void display(int data[][2], char sub[][20], char g[][3], float gpa[], int nn, float& res);
int main()
{
system("color f0");
int data[MAX][2], n, crh=0;
char sub[MAX][20], g[MAX][3], ch;
float gpa[MAX], res=0;
do

{
system("cls");
cout<<"\t\tGPA Calculator\n\n" ;

cout<<" 1. Input Data\n" ;

cout<<" 2. Display Result Card\n" ;

cout<<" 3. Exit\n\n" ;
cout<<"Ente your choice : ";
cin>>ch;
switch(ch)
{
case '1' :
do
{
cout<<"Enter number of subjects [Max.7] : ";
cin>>n;
if((n>=1)&&(n<=7))
break;
else
cout<<"Invalid Input...\n";
} 

while(1);
input(data,sub,g,n);
process(data,gpa,n,res,crh);
break;
case '2' :
display(data,sub,g,gpa,n,res);
break;
case '3' : exit(-1);
default : cout<<"Invalid Choice...\n\n";
}
system("pause>nul");
} 

while(1);
return 0;
}
void input(int data[][2], char sub[][20], char g[][3], int nn) 

{ 

for(int i=0; i<nn; i++)
{
system("cls");
cout<<"Enter the Name of Subject#"<<i+1<<" : ";
cin.ignore(10,'\n');
cin.get(sub[i],20);
cout<<"Enter Grade : ";
cin.ignore(10,'\n');
cin.get(g[i],3);
cout<<"Enter the number of Credit Hours : ";
cin>>data[i][0];
do
{
cout<<"Enter the %age : ";
cin>>data[i][1];
if((data[i][1]>=0)&&(data[i][1]<=100))
break;
else
cout<<"Invalid Input..."<<endl;
} while(1);
}
}
void process(int data[][2], float gpa[], int nn, float& res,int& crh)
{
for(int i=0; i<nn; i++)
{
if(data[i][1]>=80)
gpa[i]=4.0;
else if((data[i][1]>=75)&&(data[i][1]<80))
gpa[i]=3.5;
else if((data[i][1]>=70)&&(data[i][1]<75))
gpa[i]=3.0;
else if((data[i][1]>=65)&&(data[i][1]<70))
gpa[i]=2.5;
else if((data[i][1]>=60)&&(data[i][1]<65))
gpa[i]=2.0;
else if((data[i][1]>=55)&&(data[i][1]<60))
gpa[i]=1.5;
else
gpa[i]=1.0;
res=res+(gpa[i]*data[i][0]);
crh=crh+(data[i][0]);
}  //end of for
res=res/static_cast<float>(crh);
}
void display(int data[][2], char sub[][20], char g[][3], float gpa[], int nn, float& res)
{
system("cls");
cout<<"\t\t\tGPA CALCULATOR\n\n" <<"Sr.#\t"<<"Subject\t"<<"CRH\t"<<"%age\t<<"Grade\t"<<"GPA\n";
for(int i=0; i<nn; i++)
cout<<i+1<<"\t"<<sub[i]<<"\t"<<data[i][0]<<"\t"<<data[i][1]<<"\t"<<g[i]<<"\t<<gpa[i]<<endl;
cout<<"\n_________________________\n\n";
cout<<"\t\t\tGPA = "<<res;
}