CODEWITHSUNDEEP
c++
AEnic31
AEnic31

Reputation: 47

I want to provide two conditions for the "for" loop

I have a square matrix in my program. I want to sum the numbers on the diagonal of the matrix and multiply the numbers on the other diagonal of the matrix. I want to do it with a short way. I think "for" loop is what I'm looking for but I couldn't understand that how I can do it with "for".

Code is below:

#include<stdio.h>
#include<stdlib.h>
#include<locale.h>
#include<iostream>
#include<math.h>
#include<sstream>
#include <iomanip>
#include<time.h>
using namespace std;
int main()
{  
    setlocale(LC_ALL,"turkish");
    cout << "Problem 3\n" << "---------\n" << "Bir kare matrisin esas köşegeni üzerindeki 
    elemanlarının toplamını ve diğer köşegen üzerindeki elemanların çarpımını hesaplatan C 
    programı\n\n\n" << "Seçilen matris:\n" << "---------------\n";

    int dizi[5][5] = {{1,-25,86,-46,8},{-15,63,48,75,-21},{5,-84,-6,32,10},{41,23,6,-14,-7}, 
                      {-19,-25,40,27,61}};
    for(int i=0;i<5;i++)
    {
         for(int j=0;j<5;j++)
        {
            printf("%5d\t",dizi[i][j]);
        }
        cout << endl;
    }

    cout << endl;

    int kosegenToplam = dizi[0][0] + dizi[1][1] + dizi[2][2] + dizi[3][3] + dizi[4][4]; // Here is the summing area.
    int tersKoseCarpim = dizi[4][0] * dizi[3][1] * dizi[2][2] * dizi[1][3] * dizi[0][4]; // Here is the multiplying area.

    cout << "Seçtiğim matrisin esas köşegeni üzerindeki sayıların toplamı  = " << kosegenToplam << endl;
    cout << "Seçtiğim matrisin diğer köşegeni üzerindeki sayıların çarpımı = " << tersKoseCarpim << "\n" << endl;

    system("pause");
    return 0;
}

Thanks for helping.

Upvotes: 0

Views: 83

Answers (3)

Woodford
Woodford

Reputation: 4449

For the summing your indices are both the same and are incrementing by 1 each time. So write a simple for loop that increments from 0 to 4:

// int kosegenToplam = dizi[0][0] + dizi[1][1] + dizi[2][2] + dizi[3][3] + dizi[4][4];

int kosegenToplam = 0;
for (int i = 0; i < 5; ++i) {
    kosegenToplam += dizi[i][i];
}

For the multiplying you have 2 indices, i and j, that are different but are related by the formula i = 4-j. So write the same loop where i increments from 0 to 4 and calculate j based on the value of i:

// int tersKoseCarpim = dizi[4][0] * dizi[3][1] * dizi[2][2] * dizi[1][3] * dizi[0][4];

int tersKoseCarpim = 1;
for (int j = 0; j < 5; ++j) {
    int i = 4-j;
    tersKoseCarpim *= dizi[i][j];
}

You can combine them into a single loop:

int kosegenToplam = 0;
int tersKoseCarpim = 1;
for (int i = 0; i < 5; ++i) {
    kosegenToplam += dizi[i][i];
    tersKoseCarpim *= dizi[4-i][i];
}

Upvotes: 2

mkayaalp
mkayaalp

Reputation: 2716

Within the nested for loops you can check the indices to see if the element is on a diagonal:

int kosegenToplam = 0;
int tersKoseCarpim = 1;
for(int i=0;i<5;i++)
{
    for(int j=0;j<5;j++)
    {
        if (i == j)
            kosegenToplam += dizi[i][j];
        if (i+j == 4)
            tersKoseCarpim *= dizi[i][j];
    }
}

Upvotes: 1

Antonin GAVREL
Antonin GAVREL

Reputation: 11219

If you mean only one loop you can achieve this with modulo and divide:

for(int i=0;i<25;i++) {
   printf("%5d\t",dizi[i/5][i%5]);
   if (i % 5 == 4)
       cout << endl;
}

Upvotes: 1

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