Mercurial > octave
diff doc/interpreter/strings.txi @ 6554:5dde4dc2bcaf
[project @ 2007-04-20 17:16:50 by jwe]
author | jwe |
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date | Fri, 20 Apr 2007 17:16:50 +0000 |
parents | 5a5a09d7deb8 |
children | 8810bbf321ce |
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--- a/doc/interpreter/strings.txi Fri Apr 20 15:37:20 2007 +0000 +++ b/doc/interpreter/strings.txi Fri Apr 20 17:16:50 2007 +0000 @@ -28,27 +28,30 @@ (@pxref{Arithmetic Ops}) but double-quote marks have no other purpose in Octave, it is best to use double-quote marks to denote strings. -@c FIXME -- this is probably pretty confusing. +@cindex escape sequence notation +In double-quoted strings, the backslash character is used to introduce +@deffn{escape sequences} that reresent other characters. For example, +@samp{\n} embeds a newline character in a double-quoted string and +@samp{\"} embeds a double quote character. -@cindex escape sequence notation -Some characters cannot be included literally in a string constant. You -represent them instead with @dfn{escape sequences}, which are character -sequences beginning with a backslash (@samp{\}). +In single-quoted strings, backslash is not a special character. + +Here is an example showing the difference -One use of an escape sequence is to include a double-quote -(single-quote) character in a string constant that has been defined -using double-quote (single-quote) marks. Since a plain double-quote -would end the string, you must use @samp{\"} to represent a single -double-quote character as a part of the string. The backslash character -itself is another character that cannot be included normally. You must -write @samp{\\} to put one backslash in the string. Thus, the string -whose contents are the two characters @samp{"\} may be written -@code{"\"\\"} or @code{'"\\'}. Similarly, the string whose contents are -the two characters @samp{'\} may be written @code{'\'\\'} or @code{"'\\"}. +@example +toascii ("\n") + @result 10 +toascii ('\n') + @result [ 92 110 ] +@end example -Another use of backslash is to represent unprintable characters -such as newline. While there is nothing to stop you from writing most -of these characters directly in a string constant, they may look ugly. +You may also insert a single quote character in a single-quoted string +by using two single quote characters in succession. For example, + +@example +'I can''t escape' + @result I can't escape +@end example Here is a table of all the escape sequences used in Octave. They are the same as those used in the C programming language.