[C++] Tổng hợp các hàm tính đường chéo, tam giác... của ma trận vuông

Bài viết còn nhiều thiếu sót, rất mong sự đóng góp chỉnh sửa của các thành viên và cộng đồng

Code:
#include<iostream>
#include<conio.h>
using namespace std;
int i,j,n,a[100][100],b[100],maxd,x,dem=0;

void Nhap()
{
do
{
cout<<"Nhap so luong phan tu n= ";cin>>n;
if(n<0||n>100)
cout<<"Nhap lai!: ";
}
while(n<0||n>100);
for(i=0;i<n;i++)
for(j=0;j<n;j++)
{
cout<<"Nhap Phan Tu a["<<i<<"]["<<j<<"]= ";cin>>a[i][j];
}
}
void InNhap()
{
cout<<"\n Mang vua nhap"<<endl;
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
cout<<a[i][j]<<"\t";
cout<<endl;
}
}
void demx()
{
cout<<"\nNhap x: ";cin>>x;
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
if(a[i][j]==x)
dem++;
    }
    cout<<"\n"<<x<<" xuat hien "<<dem<<" lan.";
}
//tong cac phan tu
void Tongpt()
{ cout<<"\n\nTong cac phan tu= ";
int tong=0;
for(i=0;i<n;i++)
for(j=0;j<n;j++)
tong+=a[i][j];
cout<<tong;
}
//tong hang
void Tonghang()
{
cout<<"\n\nTong cac hang lan luot la: ";
int tongh,demhang,x;


for(i=0;i<n;i++)
{
tongh=0;
for(j=0;j<n;j++)
tongh=tongh+ a[i][j];
b[i]=tongh;
cout<<"\ntong hang "<<i+1<<"= "<<b[i];
}
maxd=b[0];
demhang=1;
for(i=0;i<n;i++)
{
if(b[i]>maxd)
{
maxd=b[i];
demhang++;
}
}
cout<<"\nHang "<<demhang<<" co tong lon nhat va = "<<maxd;
}


//tong cot
void Tongcot()
{
cout<<"\n\nTong cac cot lan luot la: ";
int tongc,maxc,demcot;
for(i=0;i<n;i++)
{
tongc=0;
for(j=0;j<n;j++)
tongc=tongc+ a[j][i];
b[i]=tongc;
cout<<"\ntong cot "<<i+1<<"= "<<b[i];
}
demcot=1;
maxc=b[0];
for(i=0;i<n;i++)
{
if(b[i]>maxc)
{
maxc=b[i];
demcot++;
}
}
cout<<"\nCot "<<demcot<<" co tong lon nhat va = "<<maxc;
}
//tong cheo chinh
void Tongcheochinh()
{
cout<<"\n\nDuong cheo chinh la:  ";
int tong=0;
for(i=0;i<n;i++)
{
tong+=a[i][i];
cout<<a[i][i]<<" ";
}
cout<<":Tong= "<<tong;
}
//tong cheo phu
void Tongcheophu()
{
cout<<"\n\nDuong cheo phu la:  ";
int tong=0;
for(i=0;i<n;i++)
{
tong+=a[i][n-i-1];
cout<<a[i][n-i-1]<<" ";
}
cout<<":Tong= "<<tong;
}
//tong tam giac tren phai
void Tongtamgiactrenphai()
{
cout<<"\n\nTam giac tren phai la: ";
int tong=0;
for(i=0;i<n;i++)
for(j=0;j<i;j++)
{
tong+=a[j][i];
cout<<a[j][i]<<" ";
}
cout<<":Tong= "<<tong;
}

//tam giac duoi phai
void Tongtamgiacduoiphai()
{
cout<<"\n\nTong tam giac duoi phai la: ";
int tong=0;
for(i=0;i<n;i++)
for(j=n-i;j<n;j++)
{
tong+=a[i][j];
cout<<a[i][j]<<" ";
}
cout<<":Tong= "<<tong;
}
//tam giac duoi trai
void Tongtamgiacduoitrai()
{
cout<<"\n\nTam giac duoi trai la: ";
int tong=0;
for(i=0;i<n;i++)
for(j=0;j<i;j++)
{
tong+=a[i][j];
cout<<a[i][j]<<" ";
}
cout<<":Tong= "<<tong;
}
void Tongtamgiactrentrai()
{
cout<<"\n\nTam giac tren trai la: ";
int tong=0;
for(i=0;i<n;i++)
for(j=0;j<n;j++)
{
tong+=a[j][n-j];
cout<<a[j][n-j]<<" ";
}
cout<<":Tong= "<<tong;
}
int main()
{
Nhap();
InNhap();
demx();
Tongpt();
Tonghang();
Tongcot();
Tongcheochinh();
Tongcheophu();
Tongtamgiactrenphai();
Tongtamgiacduoiphai();
Tongtamgiacduoitrai();
Tongtamgiactrentrai();

return 0;
}