How to debug my C++ program that calculates CGPA? - c++

Question

I have been trying to write a simple code in C++ to calculate CGPA. It is a practice code. There is no error in code when I start to build. But it is not running.
I am using codeblocks. I have checked everything. but can not find any problems in it.
#include<iostream>
#include<conio.h>
using namespace std;
int main()
{
int g,h,i,a=0, grade[g],hour[h];
char course[10];
float z=0,sum =0, result=0, totalhour=0;
cout<<"How Many Course's do you want to calculate for CGPA: ";
cin>> a;
cout<<endl;
cout<<"Please Enter your Course name, Credit hour & Grade point of the your course"<<endl;
for(i=1;i<=a;i++)
{
cout<<i<<". no Course name: ";
cin>>course[i];
cout<<"-----";
cout<<"Credit Hour: ";
cin>>hour[h];
cout<<"-----";
cout<<"Grade point: ";
cin>>grade[g];
cout<<"\n";
}
for (i=1; i<=a;i++)
{
cout<<i<<".no Course----";
z= grade[g]*hour[h];
cout<<"Grade point X Credit Hour = "<<grade[g]<<" X "<<hour[h]<<" = "<<z<<endl;
sum = sum+z;
totalhour= totalhour+hour[h];
}
result = sum / totalhour;
cout<<"Your total Credit hour Completed is : "<<totalhour<<endl;
cout<<"----Your Total CGPA is -------- = "<<result<<endl;
getch();
return 0;
}

Answer 1

You have some problems in your code:
What happens if user input is larger then 10? you assume it will be smaller (you will get undefined behavior since the array size is 10, and your for loop runs until user input)
int g,h,i,a=0, grade[g],hour[h]; - what is the size of grade and hour? you can not "dynamically" give them a size. You must tell what size they are when you declare them, unless you use dynamic containers such as std::vector.