gawk - awk not rounding with OFMT and $0

Question

I'm printing an array with 100 columns and I would like all columns to have 2 decimals. I would like to use print $0 and not have to individually specify the format for all columns.

OFMT does seen to work with $0:

echo '0.77767686 0.76555555 0.6667667 0.77878878' |awk '{CONVFMT="%.2g";OFMT="%.2g";print ($0+0);print ($0+0)"";print $0}' 

Results:

0.78
0.78
0.77767686 0.76555555 0.6667667 0.77878878

Answer 1

Note that all input is treated as strings until implicitly converted by how it is used.

OFMT is used when strings are converted to numbers numbers are printed, e.g.:

<<< 0.77767686 awk '{ print 0+$0 }' OFMT='%.2g'

CONVFMT is used when numbers are explicitly converted to strings, e.g.:

<<< 0.77767686 awk '{ print "" 0+$0 }' CONVFMT='%.2g'

Output in both cases:

0.78

The latter converts $0 into a number and then concatenates it with the empty string.

To achieve this for every column I would suggest using a sensible setting of the input and output record separators:

<<< '0.77767686 0.76555555 0.6667667 0.77878878' 
awk '{ print 0+$0 RT }' CONVFMT='%.2g' RS='[ 
]+' ORS=''

Note the two conversions, first to a number with 0+$0 then back to a string by concatenating it with RT. RT will be set to the matched record separator. Note that this is GNU awk specific, for a more portable solution, use a loop, e.g.:

<<< '0.77767686 0.76555555 0.6667667 0.77878878' 
awk '{ for (i=1; i<=NF; i++) $i+=0 } 1' CONVFMT='%.2g'

Output in both cases:

0.78 0.77 0.67 0.78

Edit - Responding to @BeeOnRope

@BeeOnRope is correct, OFMT is used as the format specifier when the print-function calls sprintf(), while CONVFMT is used in other conversions. Here is an example that illustrates the difference:

<<< 0.77767686 awk '{ n=0+$1; s=""n; print n, s }' OFMT='%.2g' CONVFMT='%.3g'

Output:

0.78 0.778

Two relevant sections from the GNU awk manual:

• https://www.gnu.org/software/gawk/manual/html_node/OFMT.html
• https://www.gnu.org/software/gawk/manual/html_node/Strings-And-Numbers.html