cond-cmp-numeric-gt.mk revision 1.1
11.1Srillig# $NetBSD: cond-cmp-numeric-gt.mk,v 1.1 2020/08/23 13:50:17 rillig Exp $
21.1Srillig#
31.1Srillig# Tests for numeric comparisons with the > operator in .if conditions.
41.1Srillig
51.1Srillig# When both sides are equal, the > operator always yields false.
61.1Srillig.if 1 > 1
71.1Srillig.error
81.1Srillig.endif
91.1Srillig
101.1Srillig# This comparison yields the same result, whether numeric or character-based.
111.1Srillig.if 1 > 2
121.1Srillig.error
131.1Srillig.endif
141.1Srillig
151.1Srillig.if 2 > 1
161.1Srillig.else
171.1Srillig.error
181.1Srillig.endif
191.1Srillig
201.1Srillig# If this comparison were character-based instead of numerical, the
211.1Srillig# 5 would be > 14 since its first digit is greater.
221.1Srillig.if 5 > 14
231.1Srillig.error
241.1Srillig.endif
251.1Srillig
261.1Srillig.if 14 > 5
271.1Srillig.else
281.1Srillig.error
291.1Srillig.endif
301.1Srillig
311.1Srillig# Scientific notation is supported, as per strtod.
321.1Srillig.if 2e7 > 1e8
331.1Srillig.error
341.1Srillig.endif
351.1Srillig
361.1Srillig.if 1e8 > 2e7
371.1Srillig.else
381.1Srillig.error
391.1Srillig.endif
401.1Srillig
411.1Srillig# Floating pointer numbers can be compared as well.
421.1Srillig# This might be tempting to use for version numbers, but there are a few pitfalls.
431.1Srillig.if 3.141 > 111.222
441.1Srillig.error
451.1Srillig.endif
461.1Srillig
471.1Srillig.if 111.222 > 3.141
481.1Srillig.else
491.1Srillig.error
501.1Srillig.endif
511.1Srillig
521.1Srillig# When parsed as a version number, 3.30 is greater than 3.7.
531.1Srillig# Since make parses numbers as plain numbers, that leads to wrong results.
541.1Srillig# Numeric comparisons are not suited for comparing version number.
551.1Srillig.if 3.30 > 3.7
561.1Srillig.error
571.1Srillig.endif
581.1Srillig
591.1Srillig.if 3.7 > 3.30
601.1Srillig.else
611.1Srillig.error
621.1Srillig.endif
631.1Srillig
641.1Srillig# As of 2020-08-23, numeric comparison is implemented as parsing both sides
651.1Srillig# as double, and then performing a normal comparison.  The range of double is
661.1Srillig# typically 16 or 17 significant digits, therefore these two numbers seem to
671.1Srillig# be equal.
681.1Srillig.if 1.000000000000000001 > 1.000000000000000002
691.1Srillig.error
701.1Srillig.endif
711.1Srillig
721.1Srilligall:
731.1Srillig	@:;
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