Awk code-golf tips

code_golf.awk

# save 1 char by using 'for' instead of 'while'
x=42;while(c)
for(x=42;c;)

# save 1 char by using a missing variable instead of ""
split($0,b,"")
split($0,b,X)

# use ternary operations when possible
if(c)a else b
c?a:b

# if there's no else, use '0' or another no-op value
if(c)a
c?a:0

# assignments are expressions, so you can combine them
if(c){a=1;b=2}
c?a=(b=2)-1:0

n=a-b;n=n<0?-n:n
n=(n=a-b)<0?-n:n

$1>p?n++:0;p=$1
p<(p=$1)?n++:0
n+=p<(p=$1)

# remove brackets as much as you can
for(…){for(…){if(…){…}else{…}}}
for(…)for(…)…?…:…

# move ++/--/+=/etc inside expressions
for(;d<80;d++)
for(;d++<80;)

# booleans are 1/0
if(a==0)
if(!a)

# split returns the length
split($0,X,",");…;print length($0)
l=split($0,X,",");…;print l

# you don't need a semicolon after a closing bracket
for(…){…};print x
for(…){…}print x

# move conditions outside the block
{$0>n?n*=2:0}
$0>n{n*=2}