110 lines
3.5 KiB
Plaintext
110 lines
3.5 KiB
Plaintext
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August 1995:
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Although the published 1003.2 standard contained the incorrect
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comparison rules of 11.2 draft as described below, no actual implementation
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of awk (that I know of) actually used those rules.
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A revision of the 1003.2 standard is in progress, and in the May 1995
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draft, the rules were fixed (based on my submissions for interpretation
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requests) to match the description given below. Thus, the next version
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of the standard will have a correct description of the comparison
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rules.
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June 1992:
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Right now, the numeric vs. string comparisons are screwed up in draft
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11.2. What prompted me to check it out was the note in gnu.bug.utils
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which observed that gawk was doing the comparison $1 == "000"
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numerically. I think that we can agree that intuitively, this should
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be done as a string comparison. Version 2.13.2 of gawk follows the
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current POSIX draft. Following is how I (now) think this
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stuff should be done.
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1. A numeric literal or the result of a numeric operation has the NUMERIC
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attribute.
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2. A string literal or the result of a string operation has the STRING
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attribute.
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3. Fields, getline input, FILENAME, ARGV elements, ENVIRON elements and the
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elements of an array created by split() that are numeric strings
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have the STRNUM attribute. Otherwise, they have the STRING attribute.
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Uninitialized variables also have the STRNUM attribute.
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4. Attributes propagate across assignments, but are not changed by
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any use. (Although a use may cause the entity to acquire an additional
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value such that it has both a numeric and string value -- this leaves the
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attribute unchanged.)
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When two operands are compared, either string comparison or numeric comparison
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may be used, depending on the attributes of the operands, according to the
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following (symmetric) matrix:
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+----------------------------------------------
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| STRING NUMERIC STRNUM
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--------+----------------------------------------------
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STRING | string string string
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NUMERIC | string numeric numeric
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STRNUM | string numeric numeric
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--------+----------------------------------------------
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So, the following program should print all OKs.
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echo '0e2 0a 0 0b
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0e2 0a 0 0b' |
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$AWK '
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NR == 1 {
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num = 0
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str = "0e2"
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print ++test ": " ( (str == "0e2") ? "OK" : "OOPS" )
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print ++test ": " ( ("0e2" != 0) ? "OK" : "OOPS" )
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print ++test ": " ( ("0" != $2) ? "OK" : "OOPS" )
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print ++test ": " ( ("0e2" == $1) ? "OK" : "OOPS" )
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print ++test ": " ( (0 == "0") ? "OK" : "OOPS" )
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print ++test ": " ( (0 == num) ? "OK" : "OOPS" )
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print ++test ": " ( (0 != $2) ? "OK" : "OOPS" )
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print ++test ": " ( (0 == $1) ? "OK" : "OOPS" )
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print ++test ": " ( ($1 != "0") ? "OK" : "OOPS" )
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print ++test ": " ( ($1 == num) ? "OK" : "OOPS" )
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print ++test ": " ( ($2 != 0) ? "OK" : "OOPS" )
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print ++test ": " ( ($2 != $1) ? "OK" : "OOPS" )
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print ++test ": " ( ($3 == 0) ? "OK" : "OOPS" )
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print ++test ": " ( ($3 == $1) ? "OK" : "OOPS" )
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print ++test ": " ( ($2 != $4) ? "OK" : "OOPS" ) # 15
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}
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{
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a = "+2"
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b = 2
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if (NR % 2)
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c = a + b
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print ++test ": " ( (a != b) ? "OK" : "OOPS" ) # 16 and 22
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d = "2a"
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b = 2
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if (NR % 2)
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c = d + b
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print ++test ": " ( (d != b) ? "OK" : "OOPS" )
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print ++test ": " ( (d + 0 == b) ? "OK" : "OOPS" )
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e = "2"
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print ++test ": " ( (e == b "") ? "OK" : "OOPS" )
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a = "2.13"
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print ++test ": " ( (a == 2.13) ? "OK" : "OOPS" )
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a = "2.130000"
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print ++test ": " ( (a != 2.13) ? "OK" : "OOPS" )
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if (NR == 2) {
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CONVFMT = "%.6f"
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print ++test ": " ( (a == 2.13) ? "OK" : "OOPS" )
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}
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}'
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