From: swift at alum dot mit dot edu Operating system: Irrelevant PHP version: Irrelevant PHP Bug Type: Documentation problem Bug description: self-contradictory documentation of escaping in single-quoted strings
Description: ------------ I quote from the node on strings in the PHP manual (www.php.net/manual/en/language.types.string.php) where it discusses single-quoted strings: I break into sentences which I reference below: (1) To specify a literal single quote, you will need to escape it with a backslash (\), like in many other languages. (2) If a backslash needs to occur before a single quote or at the end of the string, you need to double it. (3) Note that if you try to escape any other character, the backslash will also be printed! (4) So usually there is no need to escape the backslash itself. Sentence (1) is clear, though "will" should be omitted for better clarity. Sentence (2) means that a literal backslash needs to be escaped in only two cases: when it appears before a literal single quote and when it is the last character of the string. This is of course incorrect (it is contradicted by a correct example further down the page whose output is 'You deleted C:\*.*?'). What the author intends to say is much better expressed by the following: "An escaped backslash (\\) likewise specifies a literal backslash, but it is not normally necessary to escape a literal backslash. Escaping a backslash is necessary only when the context would otherwise make the backslash into an escape operator -- that is when it appears immediately before another backslash or the single quote terminating the string." Sentence (3) is unclear because it is unclear whether the reference of "other" is "backslash" or "single quote" or both. Also "try to escape" is a confusing hypothetical. A good revision would be: "A backslash followed by any character besides a single quote or another backslash is a literal backslash." Sentence (4) is confusing because it's not clear that "the backslash itself" refers to a literal backslash or an escape-operator backslash. Omit this sentence: this section should deal only with how to specify a single quoted string. Discussion of applications of strings (such as regexps) which also use the backslash as an escape operator belongs somewhere else -- or at least should be clearly separate from the discussion of simply how to specify the contents of a string. "Stringing" together the suggested revisions above: To specify a literal single quote, you need to escape it with a backslash (\), like in many other languages. An escaped backslash (\\) likewise specifies a literal backslash, but it is not normally necessary to escape a literal backslash. Escaping a backslash is necessary only when the context would otherwise make the backslash into an escape operator -- that is when it appears immediately before another backslash or the single quote terminating the string. A backslash followed by any character besides a single quote or another backslash is a literal backslash. -- Edit bug report at http://bugs.php.net/?id=36710&edit=1 -- Try a CVS snapshot (PHP 4.4): http://bugs.php.net/fix.php?id=36710&r=trysnapshot44 Try a CVS snapshot (PHP 5.1): http://bugs.php.net/fix.php?id=36710&r=trysnapshot51 Try a CVS snapshot (PHP 6.0): http://bugs.php.net/fix.php?id=36710&r=trysnapshot60 Fixed in CVS: http://bugs.php.net/fix.php?id=36710&r=fixedcvs Fixed in release: http://bugs.php.net/fix.php?id=36710&r=alreadyfixed Need backtrace: http://bugs.php.net/fix.php?id=36710&r=needtrace Need Reproduce Script: http://bugs.php.net/fix.php?id=36710&r=needscript Try newer version: http://bugs.php.net/fix.php?id=36710&r=oldversion Not developer issue: http://bugs.php.net/fix.php?id=36710&r=support Expected behavior: http://bugs.php.net/fix.php?id=36710&r=notwrong Not enough info: http://bugs.php.net/fix.php?id=36710&r=notenoughinfo Submitted twice: http://bugs.php.net/fix.php?id=36710&r=submittedtwice register_globals: http://bugs.php.net/fix.php?id=36710&r=globals PHP 3 support discontinued: http://bugs.php.net/fix.php?id=36710&r=php3 Daylight Savings: http://bugs.php.net/fix.php?id=36710&r=dst IIS Stability: http://bugs.php.net/fix.php?id=36710&r=isapi Install GNU Sed: http://bugs.php.net/fix.php?id=36710&r=gnused Floating point limitations: http://bugs.php.net/fix.php?id=36710&r=float No Zend Extensions: http://bugs.php.net/fix.php?id=36710&r=nozend MySQL Configuration Error: http://bugs.php.net/fix.php?id=36710&r=mysqlcfg
