Gauss Elimination Method For Solution To simultaneous linear equation

C++ program for Gauss Elimination method to finding solutions to simultaneous linear equation in n variable.

    #include<iostream>
    #include<fstream>
     
     
    using std::cin;
    using std::cout;
    using std::endl;
     
     
    //make a1 -> a2
    double factor(double a1,double a2){
        return (a2/a1);
    }
     
    void prog(){
        int var;
        cout<<"Enter number of variables/number of equations : ";
        cin>>var;
        cout<<"Enter equations \na1x+b1x=z1\na2x+b2x=z2 \n -- in the form -- \n  a1 b1 z1 \n  a2 b2 z2\n ";
        double arr[var+1][var+2];
        for(int i=1;i<=var;i++){
            for(int j=1;j<=var+1;j++){
                cin>>arr[i][j];
            }
        }
        int elem=1;
        //converting to upper triangular form
        for(int i=1 ;i<var; i++){
            for(int j=i+1; j<=var; j++){
                if(arr[j][elem]==0)
                    continue;
                double rat=factor(arr[i][elem],arr[j][elem]);
                for(int k=elem; k<=(var+1); k++){
                    arr[j][k]=arr[j][k]-arr[i][k]*rat;
                }
            }
            elem++;
        }
        //back substitution
        double ans[100] = {0};
        int skip=var;
        for(int i=var;i>0;i--){
            double temp_ans=arr[i][var+1];
            for(int j=i;j<=var;j++){
                if(j==skip)
                    continue;
                temp_ans-=ans[j]*arr[i][j];
            }
            if(arr[i][skip]!=0)
                ans[skip]=temp_ans/arr[i][skip];
            else
                ans[skip]=0;
            skip--;
        }
        cout<<endl;
        for(int i=1;i<=var;i++){
            cout<<"variable "<<i<<" = "<<ans[i]<<endl;
        }
    }
     
     
    int main(){
        //freopen("inps.txt","r",stdin);
        prog();
    }