Difficulties for printing pyramid pattern of numbers - c++

Question

1
232
34543
I have divided the pattern in two parts. first part is prints increment numbers and second part prints decrement numbers.
1st loop is for printing rows.
2nd loop is for printing spaces. 3rd
loop is for printing increment numbers.
4th loop is for decrement
numbers.
Code works fine up-to the 3rd loop. But the 4th loop is not giving the required output.
#include<stdio.h>
int main()
{
int i,j,n;
scanf("%d",&n);
/*Print row*/
for(i=1;i<=n;i++)
{
/*Printing Spaces*/
for (j = 1; j <= n-i; j++)
{
printf(" ");
}
/*Printing increasing number values*/
for ( int num = i; num <= 2*i-1; num++)
{
printf("%d",num);
}
/*Printing decreasing numbers value*/
for ( int num = 2*i-2; num <= i-1; num++)
{
printf("%d",num);
}
/*New line*/
printf("\n");
}
return 0;
}
Output is :
10
23
345

Answer 1

Welcome to SO.
Your first error was on the your counter on your 4th loop. Your loop should display decreasing numbers but you keep incrementing your counter (that you use to print too).
First error, decrease the counter in the 4th loop.
Second error is your condition on this first loop. You decrease a counter so your condition "While my counter is under a value" can never be false if the counter, at start of the loop, is already before the value. So you have to replace <= by >=.
And after test you will see that i-1 always print one number too far of remove your -1.
Here is your code corrected :
#include<stdio.h>
int main()
{
int i,j,n;
scanf("%d",&n);
/*Print row*/
for(i=1;i<=n;i++)
{
/*Printing Spaces*/
for (j = 1; j <= n-i; j++)
{
printf(" ");
}
/*Printing increasing number values*/
for ( int num = i; num <= 2*i-1; num++)
{
printf("%d",num);
}
/*Printing decreasing numbers value*/
for ( int num = 2*i-2; num >= i; num--)
{
printf("%d",num);
}
/*New line*/
printf("\n");
}
return 0;
}