Comments on: Number of days in a given month

By: diablomarcus

diablomarcus — Wed, 13 Apr 2011 22:35:48 +0000

This would have proven useful for problem 19 of Project Euler. I didn’t know how to do it in bash so did it in C instead

By: Rodolfo

Rodolfo — Sat, 26 Feb 2011 01:35:24 +0000

An easy solution…

cal 1 `date +%Y` | awk ‘{ day=$0 } END { print day }’

By: Konstantin Bryzgalov

Konstantin Bryzgalov — Thu, 13 Nov 2008 11:05:05 +0000

days_in_month(){ [ "$#" == "2" ] && date -d "$1/01/$2 +1month -1day" +%d [ "$#" == "1" ] && days_in_month $1 `date +%Y` [ "$#" == "0" ] && days_in_month `date +'%m %Y'` }

By: Redy

Redy — Wed, 24 Oct 2007 08:47:59 +0000

More simple. With GNU version of date you dont ned cal. Use: date -d “$MONTH/01/$YEAR +1month -1day” +%d

days_in_month() {
if [ $# -gt 1 ]; then
dim_y=$2
dim_m=$1
else
if [ $# -eq 1 ]; then
eval `date “+dim_y=%Y”`
dim_m=$1
else
eval `date “+dim_m=%m dim_y=%Y”`
fi
fi
date -d “$dim_m/01/$dim_y +1month -1day” +%d
}