projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 731d116a C |
1 | Right now, the numeric vs. string comparisons are screwed up in draft |
| 2 | 11.2. What prompted me to check it out was the note in gnu.bug.utils | |
| 3 | which observed that gawk was doing the comparison $1 == "000" | |
| 4 | numerically. I think that we can agree that intuitively, this should | |
| 5 | be done as a string comparison. Version 2.13.2 of gawk follows the | |
| 6 | current POSIX draft. Following is how I (now) think this | |
| 7 | stuff should be done. | |
| 8 | ||
| 9 | 1. A numeric literal or the result of a numeric operation has the NUMERIC | |
| 10 | attribute. | |
| 11 | ||
| 12 | 2. A string literal or the result of a string operation has the STRING | |
| 13 | attribute. | |
| 14 | ||
| 15 | 3. Fields, getline input, FILENAME, ARGV elements, ENVIRON elements and the | |
| 16 | elements of an array created by split() that are numeric strings | |
| 17 | have the STRNUM attribute. Otherwise, they have the STRING attribute. | |
| 18 | Uninitialized variables also have the STRNUM attribute. | |
| 19 | ||
| 20 | 4. Attributes propagate across assignments, but are not changed by | |
| 21 | any use. (Although a use may cause the entity to acquire an additional | |
| 22 | value such that it has both a numeric and string value -- this leaves the | |
| 23 | attribute unchanged.) | |
| 24 | ||
| 25 | When two operands are compared, either string comparison or numeric comparison | |
| 26 | may be used, depending on the attributes of the operands, according to the | |
| 27 | following (symmetric) matrix: | |
| 28 | ||
| 29 | +---------------------------------------------- | |
| 30 | | STRING NUMERIC STRNUM | |
| 31 | --------+---------------------------------------------- | |
| 32 | | | |
| 33 | STRING | string string string | |
| 34 | | | |
| 35 | NUMERIC | string numeric numeric | |
| 36 | | | |
| 37 | STRNUM | string numeric numeric | |
| 38 | --------+---------------------------------------------- | |
| 39 | ||
| 40 | So, the following program should print all OKs. | |
| 41 | ||
| 42 | echo '0e2 0a 0 0b | |
| 43 | 0e2 0a 0 0b' | | |
| 44 | $AWK ' | |
| 45 | NR == 1 { | |
| 46 | num = 0 | |
| 47 | str = "0e2" | |
| 48 | ||
| 49 | print ++test ": " ( (str == "0e2") ? "OK" : "OOPS" ) | |
| 50 | print ++test ": " ( ("0e2" != 0) ? "OK" : "OOPS" ) | |
| 51 | print ++test ": " ( ("0" != $2) ? "OK" : "OOPS" ) | |
| 52 | print ++test ": " ( ("0e2" == $1) ? "OK" : "OOPS" ) | |
| 53 | ||
| 54 | print ++test ": " ( (0 == "0") ? "OK" : "OOPS" ) | |
| 55 | print ++test ": " ( (0 == num) ? "OK" : "OOPS" ) | |
| 56 | print ++test ": " ( (0 != $2) ? "OK" : "OOPS" ) | |
| 57 | print ++test ": " ( (0 == $1) ? "OK" : "OOPS" ) | |
| 58 | ||
| 59 | print ++test ": " ( ($1 != "0") ? "OK" : "OOPS" ) | |
| 60 | print ++test ": " ( ($1 == num) ? "OK" : "OOPS" ) | |
| 61 | print ++test ": " ( ($2 != 0) ? "OK" : "OOPS" ) | |
| 62 | print ++test ": " ( ($2 != $1) ? "OK" : "OOPS" ) | |
| 63 | print ++test ": " ( ($3 == 0) ? "OK" : "OOPS" ) | |
| 64 | print ++test ": " ( ($3 == $1) ? "OK" : "OOPS" ) | |
| 65 | print ++test ": " ( ($2 != $4) ? "OK" : "OOPS" ) # 15 | |
| 66 | } | |
| 67 | { | |
| 68 | a = "+2" | |
| 69 | b = 2 | |
| 70 | if (NR % 2) | |
| 71 | c = a + b | |
| 72 | print ++test ": " ( (a != b) ? "OK" : "OOPS" ) # 16 and 22 | |
| 73 | ||
| 74 | d = "2a" | |
| 75 | b = 2 | |
| 76 | if (NR % 2) | |
| 77 | c = d + b | |
| 78 | print ++test ": " ( (d != b) ? "OK" : "OOPS" ) | |
| 79 | ||
| 80 | print ++test ": " ( (d + 0 == b) ? "OK" : "OOPS" ) | |
| 81 | ||
| 82 | e = "2" | |
| 83 | print ++test ": " ( (e == b "") ? "OK" : "OOPS" ) | |
| 84 | ||
| 85 | a = "2.13" | |
| 86 | print ++test ": " ( (a == 2.13) ? "OK" : "OOPS" ) | |
| 87 | ||
| 88 | a = "2.130000" | |
| 89 | print ++test ": " ( (a != 2.13) ? "OK" : "OOPS" ) | |
| 90 | ||
| 91 | if (NR == 2) { | |
| 92 | CONVFMT = "%.6f" | |
| 93 | print ++test ": " ( (a == 2.13) ? "OK" : "OOPS" ) | |
| 94 | } | |
| 95 | }' |