Hollow Diamond Pattern in Cpp

I written a pattern printing code for odd number of lines of the famous hollow diamond (stars + spaces + stars) code in cpp as follows :-

#include <iostream>
using namespace std;
int main(){
    int tr;
    cin >> tr;
    //first row
    int firststar = 1;
    while (firststar <= tr){
        cout << "*";
        firststar++;
    }
    cout << endl;

int firsthalf = 1;
while (firsthalf <= (tr-1/2)) {
    //stars
    int star1 = 1;
    while (star1 <= (((tr-1/2)+1)/2-firsthalf) ){
        cout << "*" ;
        star1++;
    }
    //spaces
    int spaces1 = 1;
    while (spaces1 <= 2 * firsthalf - 1){
        cout <<" ";
        spaces1++;
    }

    //stars
    star1 = 1;
    while (star1 <= (((tr-1/2)+1)/2-firsthalf) ){
        cout << "*" ;
        star1++;
    }
    firsthalf++;
    cout << endl;
}

int secondhalf = 1;
while (secondhalf <= ((tr-1) /2)-1){
    //stars
    int star2 = 1;
    while (star2 <= secondhalf+1){
        cout << "*" ;
        star2++;
    }

    //spaces
    int spaces2 = 1;
    while (spaces2 <= 2 * ((tr - 1) / 2 - secondhalf) - 1){
        cout << " ";
        spaces2++;
    }

    //stars
    star2 = 1;
    while (star2 <= secondhalf+1){
        cout << "*" ;
        star2++;
    }
    cout<< endl;
    secondhalf++;
}
//last row
int laststar = 1;
while (laststar <= tr){
    cout << "*";
    laststar++;
}
return 0;}

I tried running the code after dry testing the code (checking the logic of the stars and spaces) several times, but it still prints extra spaces/ lines after the first half

>Solution :

Honestly your code would be much shorter and less bug-prone, if you would just reuse the code as functions. For example:

#include <iostream>
using namespace std;

void draw(char symbol, size_t count) {
    while (count--){
        cout << symbol;
    }   
}

void drawRow(size_t numStars, size_t size) {
    draw('*', numStars);
    draw(' ', size - 2*numStars);
    draw('*', numStars);
    cout << endl;
}

int main()
{
  int size = 7;
  int radius = size / 2;
  // first row
  draw('*', size);
  cout << endl;
  
  // upper half
  for (int numStars = radius; numStars > 0; --numStars) {
      drawRow(numStars, size);
  }
  // lower half
  for (int numStars = 2; numStars <= radius; ++numStars) {
      drawRow(numStars, size);
  }
  // last row
  draw('*', size);
}

This would draw you:

*******
*** ***
**   **
*     *
**   **
*** ***
*******

You just need adjust this code to provide size of your drawing from console input

EDIT – Version without defining functions

#include <iostream>
using namespace std;

int main()
{
  int size = 7;
  int radius = size / 2;
  // first row
  {
    int numSymbols = size;
    while (numSymbols--) {
        cout << '*';
    }   
  }
  cout << endl;
  
  int numStars = size / 2 + 1;
  for (int row = 1; row < size-1; ++row) {
      // while first half (rows 1, 2, 3, ... size/2) decrease number of stars
      // while second half (rows size/2+1, size/2+2, ..., size-1)
      if (row <= size / 2) {
         --numStars;    
      } else {
         ++numStars;   
      }

      if (numStars < 0) {
         numStars = -numStars;   
      }
      
      {
        int numSymbols = numStars;
        while (numSymbols--) {
            cout << '*';
        }   
      }
      
      {
        int numSymbols = size - 2*numStars;
        while (numSymbols--) {
            cout << ' ';
        }   
      }
      
      {
        int numSymbols = numStars;
        while (numSymbols--) {
            cout << '*';
        }   
      }
      cout << endl;
  }

  // last row
  {
    int numSymbols = size;
    while (numSymbols--) {
        cout << '*';
    }   
  }
  cout << endl;
}