I want to print c pattern as upper triangle - c

Question

I want to print some C pattern for upper triagnle which sholud print numeric value 1 to 10.
Now my code is like this:-
#include <stdio.h>
int main() {
int j = 1, k, l, i;
for (i = 4; i >= 1; i--) {
for (k = i - 1; k >= 0; k--) {
printf(" ");
}
for (l = 4; l >= i; l--) {
printf("%2d", j);
j++;
}
printf("\n");
}
return 0;
}
Its output is fine but when my value reach near 10 it's space is missing.
How can I resolve it?
My output looks like
1
2 3
4 5 6
7 8 910
It should be:
1
2 3
4 5 6
7 8 9 10

Answer 1

You can change the alignment by using the - sign. This makes it left-justified.
Replace
printf("%2d",j);
with
printf("%-2d",j);
Live demo
If you want the bottom of the pyramid to be completely to the left with no space you can replace
for (k = i - 1; k >= 0; k--)
with
for (k = i - 1; k > 0; k--)
EDIT:
As #chqrlie pointed out this will leave a trailing blank space in every line except the last one, this can be fixed like:
//...
for (i = 4; i >= 1; i--)
{
for (k = i - 1; k > 0; k--) // change from k >= 0 to k > 0
{
printf(" ");
}
for (l = 4; l >= i; l--)
{
printf(" %d", j); // change from "%2d" to " %d"
j++;
}
printf("\n");
}
//...
Live demo

Answer 2

For this problem, with n lines of output, you need to produce n - i spaces at the beginning of line i and i numbers each preceded by a space. Instead of "%2d", use " %d" and output one less space at the start of each line. You can use printf to output an arbitrary number of spaces using %*s and an empty string.
Here is a modified version:
#include <stdio.h>
int main() {
int i; // line number
int j = 1; // starting number
int n = 4; // number of lines
int k;
for (i = 1; i <= n; i++) {
printf("%*s", n - i, ""); // output n - i spaces
for (k = 0; k < i; k++) {
printf(" %d", j);
j++;
}
printf("\n");
}
return 0;
}
Output:
1
2 3
4 5 6
7 8 9 10

Answer 3

It can be solved in two ways:
One way to resolve this is by simply add spacing (padding) for each character you are printing.
#include<stdio.h>
int main()
{
int j=1,k,l,i;
for(i=4;i>=1;i--){
for(k=i-1;k>=0;k--){
printf(" ");
}
for(l=4;l>=i;l--){
printf(" %2d ",j); //Padding added
^ ^
j++;
}
printf("\n");
}
return 0;
}
Secondly you can change the alignment by using - sign
#include<stdio.h>
int main()
{
int j=1,k,l,i;
for(i=4;i>=1;i--){
for(k=i-1;k>=0;k--){
printf(" ");
}
for(l=4;l>=i;l--){
printf("-%2d",j); //Left justified
^
j++;
}
printf("\n");
}
return 0;
}

Answer 4

Amongst the other good answers, another way is to use printf("%d ", j); instead of printf("%2d", j); - Note the white space ' ' behind the %d format specifier. - This method has the disadvantage that you have a trailing white space after 10 but it accomplishes the (obvious) desired output:
Online example
#include <stdio.h>
int main (void)
{
int j = 1, k, l, i;
for (i = 4; i >= 1; i--){
for (k = i - 1; k >= 0; k--) {
printf(" ");
}
for(l = 4; l >= i; l--) {
printf("%d ", j);
j++;
}
printf("\n");
}
return 0;
}
Output:
1
2 3
4 5 6
7 8 9 10