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author | luigi <luigi@FreeBSD.org> | 2008-12-26 22:31:45 +0000 |
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committer | luigi <luigi@FreeBSD.org> | 2008-12-26 22:31:45 +0000 |
commit | a371cf7a492d25bdb9515f5e43f8f529da0db039 (patch) | |
tree | b90e09ee231e1179a41d7938f1bd9b930e08e1cc | |
parent | e06c47109ccf822fe4f49c9a8e5c428fe0488b7e (diff) | |
download | FreeBSD-src-a371cf7a492d25bdb9515f5e43f8f529da0db039.zip FreeBSD-src-a371cf7a492d25bdb9515f5e43f8f529da0db039.tar.gz |
Clarify the behaviour of conditionals when dealing with comparisons.
In particular, point out that string comparison can only use != and ==
(how weird, given that the underlying call to strcmp returns more
information), that floating point values are correctly interpreted
as numbers, and that the left-hand side must be a variable expansion.
MFC after: 3 weeks
-rw-r--r-- | usr.bin/make/make.1 | 35 |
1 files changed, 23 insertions, 12 deletions
diff --git a/usr.bin/make/make.1 b/usr.bin/make/make.1 index 44421e5..6333509 100644 --- a/usr.bin/make/make.1 +++ b/usr.bin/make/make.1 @@ -1130,24 +1130,35 @@ has been defined. .Pp An .Ar expression -may also be an arithmetic or string comparison, with the left-hand side -being a variable expansion. -Variable expansion is -performed on both sides of the comparison, after which the integral +may also be a numeric or string comparison: +in this case, the left-hand side +.Ar must be +a variable expansion, whereas the right-hand side can be a +constant or a variable expansion. +Variable expansion is performed on both sides, after which the resulting values are compared. A value is interpreted as hexadecimal if it is preceded by 0x, otherwise it is decimal; octal numbers are not supported. -The standard C relational operators are all supported. -If after -variable expansion, either the left or right hand side of a +.Pp +String comparison can only use the .Sq Ic == or .Sq Ic != -operator is not an integral value, then -string comparison is performed between the expanded -variables. -If no relational operator is given, it is assumed that the expanded -variable is being compared against 0. +operators, whereas numeric values (both integer and floating point) +can also be compared using the +.Sq Ic > +, +.Sq Ic >= +, +.Sq Ic < +and +.Sq Ic <= +operators. +.Pp +If no relational operator (and right-hand value) are given, an implicit +.Sq Ic != 0 +is used. However be very careful in using this feature especially +when the left-hand side variable expansion returns a string. .Pp When .Nm |