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Diffstat (limited to 'doc/gawk.texi')
| -rw-r--r-- | doc/gawk.texi | 55 |
1 files changed, 53 insertions, 2 deletions
diff --git a/doc/gawk.texi b/doc/gawk.texi index 3d910ee0..b210da10 100644 --- a/doc/gawk.texi +++ b/doc/gawk.texi @@ -611,6 +611,9 @@ particular records in a file and perform operations upon them. This is an advanced method of input. * Conversion:: The conversion of strings to numbers and vice versa. +* Strings And Numbers:: How @command{awk} Converts Between + Strings And Numbers. +* Locale influences conversions:: How the locale may affect conversions. * All Operators:: @command{gawk}'s operators. * Arithmetic Ops:: Arithmetic operations (@samp{+}, @samp{-}, etc.) @@ -10663,6 +10666,19 @@ sequences @node Conversion @subsection Conversion of Strings and Numbers +Number to string and string to number conversion are generally +straightforward. There can be subtleties to be aware of; +this @value{SECTION} discusses this important facet of @command{awk}. + +@menu +* Strings And Numbers:: How @command{awk} Converts Between Strings And + Numbers. +* Locale influences conversions:: How the locale may affect conversions. +@end menu + +@node Strings And Numbers +@subsubsection How @command{awk} Converts Between Strings And Numbers + @cindex converting, strings to numbers @cindex strings, converting @cindex numbers, converting @@ -10732,6 +10748,35 @@ b = a "" @code{b} has the value @code{"12"}, not @code{"12.00"}. @value{DARKCORNER} +@cindex sidebar, Pre-POSIX @command{awk} Used @code{OFMT} For String Conversion +@ifdocbook +@docbook +<sidebar><title>Pre-POSIX @command{awk} Used @code{OFMT} For String Conversion</title> +@end docbook + +@cindex POSIX @command{awk}, @code{OFMT} variable and +@cindex @code{OFMT} variable +@cindex portability, new @command{awk} vs.@: old @command{awk} +@cindex @command{awk}, new vs.@: old, @code{OFMT} variable +Prior to the POSIX standard, @command{awk} used the value +of @code{OFMT} for converting numbers to strings. @code{OFMT} +specifies the output format to use when printing numbers with @code{print}. +@code{CONVFMT} was introduced in order to separate the semantics of +conversion from the semantics of printing. Both @code{CONVFMT} and +@code{OFMT} have the same default value: @code{"%.6g"}. In the vast majority +of cases, old @command{awk} programs do not change their behavior. +@xref{Print}, for more information on the @code{print} statement. + +@docbook +</sidebar> +@end docbook +@end ifdocbook + +@ifnotdocbook +@cartouche +@center @b{Pre-POSIX @command{awk} Used @code{OFMT} For String Conversion} + + @cindex POSIX @command{awk}, @code{OFMT} variable and @cindex @code{OFMT} variable @cindex portability, new @command{awk} vs.@: old @command{awk} @@ -10744,6 +10789,11 @@ conversion from the semantics of printing. Both @code{CONVFMT} and @code{OFMT} have the same default value: @code{"%.6g"}. In the vast majority of cases, old @command{awk} programs do not change their behavior. @xref{Print}, for more information on the @code{print} statement. +@end cartouche +@end ifnotdocbook + +@node Locale influences conversions +@subsubsection Locales Can Influence Conversion Where you are can matter when it comes to converting between numbers and strings. The local character set and language---the @dfn{locale}---can @@ -12632,6 +12682,7 @@ of others let you control how @command{awk} behaves. Numbers are automatically converted to strings, and strings to numbers, as needed by @command{awk}. Numeric values are converted as if they were formatted with @code{sprintf()} using the format in @code{CONVFMT}. +Locales can influence the conversions. @item @command{awk} provides the usual arithmetic operators (addition, @@ -30354,7 +30405,7 @@ the following computes 5<superscript>4<superscript>3<superscript>2</superscript></superscript></superscript>, @c @end docbook the result of which is beyond the -limits of ordinary @command{gawk} numbers: +limits of ordinary hardware double-precision floating point values: @example $ @kbd{gawk -M 'BEGIN @{} @@ -30462,7 +30513,7 @@ source code constants.) Support for the special IEEE 754 floating point values ``Not A Number'' (NaN), positive Infinity (``inf'') and negative Infinity (``@minus{}inf''). In particular, the format for these values is as specified by the ISO 1999 -C standard, which ignores case and can allow machine-dependent additional +C standard, which ignores case and can allow implementation-dependent additional characters after the @samp{nan} and allow either @samp{inf} or @samp{infinity}. @end itemize |