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Leap year calculation

Terminal - Leap year calculation
year=2010; math=`echo "$year%4" | bc`; [ ! -z $year ] && [ $math -eq 0 ] && echo "$year is leap year!" || echo "$year isn't leap year";
2010-03-30 15:33:00
User: mvrilo
Functions: echo
-1
Leap year calculation

Alternatives

There are 9 alternatives - vote for the best!

Terminal - Alternatives
leapyear() { [ $(date -d "Dec 31, $1" +%j) == 366 ] && echo leap || echo not leap; }
leapyear() { if [ $[$1 % 4] -eq 0 ] && [ $[$1 % 100] -ne 0 ] || [ $[$1 % 400] -eq 0 ]; then echo $1' is a leap year!'; else echo $1' is not a leap year.'; fi; }
2010-03-30 17:19:20
User: kaedenn
Functions: echo
Tags: echo test
-2

Tested on bash, and follows all the rules about leap years.

Know a better way?

If you can do better, submit your command here.

What others think

This doesn't work for all leap years. If a year is evenly divisible by 4 and 100, but not 400, then it's not a leap year. For example, 2200 is divisible by 4, but it's not a leap year. Here's a bash function that takes a year as an argument and returns whether or not it's a leap year.

leapyear(){ [ $[$1%400] -eq 0 ]&&{ echo $1' is a leap year!';return;};[ $[$1%100] -eq 0 ]&&{ echo $1' is not a leap year.';return;};[ $[$1%4] -eq 0 ]&&echo $1' is a leap year!'||echo $1' is not a leap year.';}
Comment by eightmillion 282 weeks and 5 days ago

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