Formatting output into even columns?

Uncle Rico · 08-16-2005, 04:24 PM

Hey guys, quick question. Is there anything in C (working in Linux here) that allows you to format output into even looking columns even if the corresponding output is printed horizontally? ..err, that's hard to explain. Basically I've got some code that performs DNS lookups on a list of machines (functionality is irrelevant to my question) and outputs the results. Right now, the output might look something like this:

Code:

host.domain.com              12.12.12.12
host123.domain.com              123.123.123.123
h.domain.com              21.21.21.21
blah.domain2.com              32.32.32.32
aaa.domain.com              111.111.111.111

while it displays the right information, the output of the program as you can see is uneven and looks generally sloppy. What I'd like to do is have it's output look more like:

Code:

host.domain.com                 12.12.12.12
host123.domain.com           123.123.123.123
h.domain.com                      21.21.21.21
blah.domain2.com               32.32.32.32
aaa.domain.com                  111.111.111.111

so that even though the data that goes together (host -- ip) is printed horizontally, columns of the text are outputted evenly. Is this possible

? Thanks.

--EDIT--:
In the example of how I want the output to look it still came out uneven, I guess thanks to how the forum parses my thread. Trust me though, the first number in the first octect of each IP in my example all line up >_<

**Dave_Sinkula** · 08-16-2005, 04:40 PM

There are width specifiers for printf.

Code:

#include <stdio.h>

int main(void)
{
   static const struct
   {
      const char *host, *ip;
   } text[] =
   {
      {"host.domain.com", "12.12.12.12"},
      {"host123.domain.com", "123.123.123.123"},
      {"h.domain.com", "21.21.21.21"},
      {"blah.domain2.com", "32.32.32.32"},
      {"aaa.domain.com", "111.111.111.111"},
   };
   size_t i;
   for ( i = 0; i < sizeof text / sizeof *text; ++i )
   {
      printf("%-64s %s\n", text[i].host, text[i].ip);
   }
   return 0;
}

/* my output
host.domain.com                                                  12.12.12.12
host123.domain.com                                               123.123.123.123
h.domain.com                                                     21.21.21.21
blah.domain2.com                                                 32.32.32.32
aaa.domain.com                                                   111.111.111.111
*/

Uncle Rico · 08-16-2005, 05:10 PM

Perfect! That's exactly what I needed, thanks

08-16-2005, 04:24 PM	#1
Uncle Rico Registered User Join Date: Feb 2005 Posts: 11	Formatting output into even columns? Hey guys, quick question. Is there anything in C (working in Linux here) that allows you to format output into even looking columns even if the corresponding output is printed horizontally? ..err, that's hard to explain. Basically I've got some code that performs DNS lookups on a list of machines (functionality is irrelevant to my question) and outputs the results. Right now, the output might look something like this: Code: host.domain.com 12.12.12.12 host123.domain.com 123.123.123.123 h.domain.com 21.21.21.21 blah.domain2.com 32.32.32.32 aaa.domain.com 111.111.111.111 while it displays the right information, the output of the program as you can see is uneven and looks generally sloppy. What I'd like to do is have it's output look more like: Code: host.domain.com 12.12.12.12 host123.domain.com 123.123.123.123 h.domain.com 21.21.21.21 blah.domain2.com 32.32.32.32 aaa.domain.com 111.111.111.111 so that even though the data that goes together (host -- ip) is printed horizontally, columns of the text are outputted evenly. Is this possible ? Thanks. --EDIT--: In the example of how I want the output to look it still came out uneven, I guess thanks to how the forum parses my thread. Trust me though, the first number in the first octect of each IP in my example all line up >_< Last edited by Uncle Rico; 08-16-2005 at 04:31 PM.
Uncle Rico is offline

08-16-2005, 05:10 PM	#3
Uncle Rico Registered User Join Date: Feb 2005 Posts: 11	Perfect! That's exactly what I needed, thanks
Uncle Rico is offline

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