printf with multiple columns

This function prints every number starting from 0000 to 1000.

#include <stdio.h>

int main() {
    int i = 0;
    while ( i <= 1000 ) {
        printf( "%04d\n", i);
        i = i + 1; 
    }
    return 0;
}

The output looks like this:

0000

0001

0002

etc..

How can I make this more presentable using three different columns (perhaps using \t ) to have t开发者_如何学运维he output look like this:

0000 0001 0002

0003 0004 0005

etc..

This is how I'd do it, to eliminate the potentially expensive if/?: statement:

char nl[3] = {' ', ' ', '\n'};
while ( i <= 1000 ) {
   printf("%04d%c", i, nl[i%3]);
   ++i; 
}

Note that the modulo division may be much more expensive than the branching anyhow, but this depends on your architecture.

To get 3 columns you need to print new line character only after each 3 numbers (in your case after a number if its remainder when divided by 3 is 2):

The simplest approach:

while ( i <= 1000 ) {
    if (i%3 == 2)
       printf( "%04d\n", i);
    else
       printf( "%04d ", i);
    i = i + 1; 
}

Or as pointed in comment you can make it shorter using ternary operator:

while ( i <= 1000 ) {
   printf("%04d%c", i, i%3==2 ? '\n' : ' ');
   ++i; 
}

while ( i <= 1000 )
{
   printf( i%3?"%04d ":"%04d\n", i );
   ++i;
}

should also works.

The only way I got it to work perfectly in terminal (console) was literally padding the string with a loop. The nice part is that you can choose which char to pad it with, like "Text .......... 234". Without manual padding most lines got aligned by printf, but a few remained little out of alignment.

  # This gets available cols in terminal window:
  w_cols=`tput cols`

  col2=15
  let "col1=($w_cols - $col2)"

  small="Hey just this?"
  bigone="Calm down, this text will be printed nicelly"     
  padchar='.'

  let "diff=${#bigone} - ${#small}"

  for ((i=0; i<$diff; i++)); 
    do
       small="${small}$pad_char"
    done

 # The '-' in '%-80s' below makes the first column left aligned.
 # Default is right all columns:

  printf "%-${col1}s\t%${col2}d\n"  "$small"  123456
  printf "%-${col1}s\t%${col2}d\n"  "$bigone"  123

The result is something like

  Hey just this?.....................................   123456
  Calm down, this text will be printed nicelly ......      123