error in friend function declaration c++

Question

I am getting a compiling error.

||=== Build: Debug in 24.06.01 (compiler: GNU GCC Compiler) ===|

G:\C++\24.06.01\main.cpp|22|error: 'void sum(Sb1, Sb2)' redeclared as different kind of symbol|

G:\C++\24.06.01\main.cpp|5|note: previous declaration 'int sum [40]'|

G:\C++\24.06.01\main.cpp|36|error: 'void sum(Sb1, Sb2)' redeclared as different kind of symbol|

G:\C++\24.06.01\main.cpp|5|note: previous declaration 'int sum [40]'|

G:\C++\24.06.01\main.cpp||In function 'void sum(Sb1, Sb2)':|

G:\C++\24.06.01\main.cpp|38|error: 'void sum(Sb1, Sb2)' redeclared as different kind of symbol|

G:\C++\24.06.01\main.cpp|5|note: previous declaration 'int sum [40]'|

G:\C++\24.06.01\main.cpp||In function 'int main()':|

G:\C++\24.06.01\main.cpp|69|error: 'sum' cannot be used as a function|

||=== Build failed: 4 error(s), 0 warning(s) (0 minute(s), 1 second(s)) ===|

please help !!

#include<iostream>
#include<conio.h>
#include<stdlib.h>
using namespace std;
int sum[40];
int roll[40];
int n;
class Sb1;
class Sb2;
class Sb1
{
    public:
    float marks1[40];
    void markssb1()
    {
       for(int i=0;i<n;i++)
       {
         cout<<"Enter Marks in subject 1 \n";
         cin>>marks1[40];
       }
    }
    friend void sum(Sb1,Sb2);
};
class Sb2
{
    public:
    float marks2[40];
    void markssb2()
    {
       for(int i=0;i<n;i++)
       {
         cout<<"Enter Marks in subject 2 \n";
         cin>>marks2[40];
       }
    }
    friend void sum(Sb1,Sb2);
};
void sum(Sb1 obj1,Sb2 obj2)
{
    for(int i=0;i<n;i++)
    {
        sum[i]=obj1.marks1[i]+obj2.marks2[i];
    }
}
void display()
{
    cout<<"Serial Number\t\t\tRoll Number\t\t\tTotal Marks\n";
    cout<<"----------------------------------------------------------------------------\n";
    for(int i=0;i<n;i++)
    {
        cout<<i<<"\t\t\t\t"<<roll[i]<<"\t\t\t\t"<<sum[i]<<endl;
    }
}
int main()
{
    Sb1 obj1;
    Sb2 obj2;
   cout<<"Enter number of students (Maximum 40 students)\n";
   cin>>n;
   if(n<=40)
    {
        for(int i=0;i<n;i++)
        {
            cout<<"Enter Roll Number of student "<<i+1<<endl;
            cin>>roll[i];
            obj1.markssb1();
            obj2.markssb2();
        }
        sum(obj1,obj2);
        display();
    }
    else
    {
      cout<<"Number of students entered exceed 40\n";
    }
    return 0;
    getch();
}

Answer 1

You have already declared 'sum' as a global variable:

int sum[40];

C++ doesn't allow redifining names. You can either change the variable or the function name to solve this problem.