13 lines
384 B
Bash
13 lines
384 B
Bash
dec31wd() {
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# return weekday (time_t tm_wday, 0=Sunday) of December 31st of the given year
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typeset -i y=$1
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echo $(( (y + y / 4 - y / 100 + y / 400) % 7 ))
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}
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# the year is long if the year starts or ends on a Thursday (starts on a
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# Thursday = the previous year ends on a Wednesday)
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long_year() {
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typeset -i y=$1
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(( 4 == $(dec31wd $y) || 3 == $(dec31wd $(( y - 1 ))) ))
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}
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