diff options
Diffstat (limited to 'doc/format.n')
| -rw-r--r-- | doc/format.n | 122 |
1 files changed, 71 insertions, 51 deletions
diff --git a/doc/format.n b/doc/format.n index 846e832..076a820 100644 --- a/doc/format.n +++ b/doc/format.n @@ -5,10 +5,8 @@ '\" See the file "license.terms" for information on usage and redistribution '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. '\" -'\" RCS: @(#) $Id: format.n,v 1.12 2005/05/10 18:34:00 kennykb Exp $ -'\" -.so man.macros .TH format n 8.1 Tcl "Tcl Built-In Commands" +.so man.macros .BS '\" Note: do not modify the .SH NAME line immediately below! .SH NAME @@ -19,9 +17,8 @@ format \- Format a string in the style of sprintf .SH INTRODUCTION .PP -This command generates a formatted string in the same way as the -ANSI C \fBsprintf\fR procedure (it uses \fBsprintf\fR in its -implementation). +This command generates a formatted string in a fashion similar to the +ANSI C \fBsprintf\fR procedure. \fIFormatString\fR indicates how to format the result, using \fB%\fR conversion specifiers as in \fBsprintf\fR, and the additional arguments, if any, provide values to be substituted into the result. @@ -44,15 +41,16 @@ of all of the conversion specifiers in \fIformatString\fR. .PP Each conversion specifier may contain up to six different parts: an XPG3 position specifier, -a set of flags, a minimum field width, a precision, a length modifier, +a set of flags, a minimum field width, a precision, a size modifier, and a conversion character. Any of these fields may be omitted except for the conversion character. The fields that are present must appear in the order given above. The paragraphs below discuss each of these fields in turn. +.SS "OPTIONAL POSITIONAL SPECIFIER" .PP If the \fB%\fR is followed by a decimal number and a \fB$\fR, as in -``\fB%2$d\fR'', then the value to convert is not taken from the -next sequential argument. +.QW \fB%2$d\fR , +then the value to convert is not taken from the next sequential argument. Instead, it is taken from the argument indicated by the number, where 1 corresponds to the first \fIarg\fR. If the conversion specifier requires multiple arguments because @@ -62,6 +60,7 @@ given by the number. This follows the XPG3 conventions for positional specifiers. If there are any positional specifiers in \fIformatString\fR then all of the specifiers must be positional. +.SS "OPTIONAL FLAGS" .PP The second portion of a conversion specifier may contain any of the following flag characters, in any order: @@ -76,8 +75,8 @@ Specifies that a number should always be printed with a sign, even if positive. .TP 10 \fIspace\fR -Specifies that a space should be added to the beginning of the -number if the first character isn't a sign. +Specifies that a space should be added to the beginning of the +number if the first character is not a sign. .TP 10 \fB0\fR Specifies that the number should be padded on the left with @@ -88,13 +87,16 @@ Requests an alternate output form. For \fBo\fR and \fBO\fR conversions it guarantees that the first digit is always \fB0\fR. For \fBx\fR or \fBX\fR conversions, \fB0x\fR or \fB0X\fR (respectively) will be added to the beginning of the result unless it is zero. +For \fBb\fR conversions, \fB0b\fR +will be added to the beginning of the result unless it is zero. For all floating-point conversions (\fBe\fR, \fBE\fR, \fBf\fR, \fBg\fR, and \fBG\fR) it guarantees that the result always has a decimal point. For \fBg\fR and \fBG\fR conversions it specifies that trailing zeroes should not be removed. +.SS "OPTIONAL FIELD WIDTH" .PP -The third portion of a conversion specifier is a number giving a +The third portion of a conversion specifier is a decimal number giving a minimum field width for this conversion. It is typically used to make columns line up in tabular printouts. If the converted argument contains fewer characters than the @@ -106,7 +108,8 @@ may be used to specify padding with zeroes on the left or with spaces on the right, respectively. If the minimum field width is specified as \fB*\fR rather than a number, then the next argument to the \fBformat\fR command -determines the minimum field width; it must be a numeric string. +determines the minimum field width; it must be an integer value. +.SS "OPTIONAL PRECISION/BOUND" .PP The fourth portion of a conversion specifier is a precision, which consists of a period followed by a number. @@ -124,16 +127,23 @@ printed; if the string is longer than this then the trailing characters will be If the precision is specified with \fB*\fR rather than a number then the next argument to the \fBformat\fR command determines the precision; it must be a numeric string. +.SS "OPTIONAL SIZE MODIFIER" .PP -The fifth part of a conversion specifier is a length modifier, -which must be \fBh\fR or \fBl\fR. -If it is \fBh\fR it specifies that the numeric value should be -truncated to a 16-bit value before converting. -This option is rarely useful. -If it is \fBl\fR it specifies that the numeric value should be (at -least) a 64-bit value. If neither \fBh\fR nor \fBl\fR are present, -numeric values are interpreted as being values of the width of the -native machine word, as described by \fBtcl_platform(wordSize)\fR. +The fifth part of a conversion specifier is a size modifier, +which must be \fBll\fR, \fBh\fR, or \fBl\fR. +If it is \fBll\fR it specifies that an integer value is taken +without truncation for conversion to a formatted substring. +If it is \fBh\fR it specifies that an integer value is +truncated to a 16-bit range before converting. This option is rarely useful. +If it is \fBl\fR it specifies that the integer value is +truncated to the same range as that produced by the \fBwide()\fR +function of the \fBexpr\fR command (at least a 64-bit range). +If neither \fBh\fR nor \fBl\fR are present, the integer value is +truncated to the same range as that produced by the \fBint()\fR +function of the \fBexpr\fR command (at least a 32-bit range, but +determined by the value of the \fBwordSize\fR element of the +\fBtcl_platform\fR array). +.SS "MANDATORY CONVERSION TYPE" .PP The last thing in a conversion specifier is an alphabetic character that determines what kind of conversion to perform. @@ -146,16 +156,20 @@ Convert integer to signed decimal string. Convert integer to unsigned decimal string. .TP 10 \fBi\fR -Convert integer to signed decimal string; the integer may either be -in decimal, in octal (with a leading \fB0\fR) or in hexadecimal -(with a leading \fB0x\fR). +Convert integer to signed decimal string (equivalent to \fBd\fR). .TP 10 \fBo\fR Convert integer to unsigned octal string. .TP 10 \fBx\fR or \fBX\fR Convert integer to unsigned hexadecimal string, using digits -``0123456789abcdef'' for \fBx\fR and ``0123456789ABCDEF'' for \fBX\fR). +.QW 0123456789abcdef +for \fBx\fR and +.QW 0123456789ABCDEF +for \fBX\fR). +.TP 10 +\fBb\fR +Convert integer to binary string, using digits 0 and 1. .TP 10 \fBc\fR Convert integer to the Unicode character it represents. @@ -164,13 +178,13 @@ Convert integer to the Unicode character it represents. No conversion; just insert string. .TP 10 \fBf\fR -Convert floating-point number to signed decimal string of +Convert number to signed decimal string of the form \fIxx.yyy\fR, where the number of \fIy\fR's is determined by the precision (default: 6). If the precision is 0 then no decimal point is output. .TP 10 -\fBe\fR or \fBe\fR -Convert floating-point number to scientific notation in the +\fBe\fR or \fBE\fR +Convert number to scientific notation in the form \fIx.yyy\fBe\(+-\fIzz\fR, where the number of \fIy\fR's is determined by the precision (default: 6). If the precision is 0 then no decimal point is output. @@ -179,46 +193,49 @@ printed instead of \fBe\fR. .TP 10 \fBg\fR or \fBG\fR If the exponent is less than \-4 or greater than or equal to the -precision, then convert floating-point number as for \fB%e\fR or +precision, then convert number as for \fB%e\fR or \fB%E\fR. Otherwise convert as for \fB%f\fR. Trailing zeroes and a trailing decimal point are omitted. .TP 10 \fB%\fR No conversion: just insert \fB%\fR. -.LP -For the numerical conversions the argument being converted must -be an integer or floating-point string; format converts the argument -to binary and then converts it back to a string according to -the conversion specifier. .SH "DIFFERENCES FROM ANSI SPRINTF" .PP The behavior of the format command is the same as the ANSI C \fBsprintf\fR procedure except for the following differences: .IP [1] -\fB%p\fR and \fB%n\fR specifiers are not currently supported. +Tcl guarantees that it will be working with UNICODE characters. .IP [2] -For \fB%c\fR conversions the argument must be a decimal string, -which will then be converted to the corresponding character value. +\fB%p\fR and \fB%n\fR specifiers are not supported. .IP [3] -The \fBl\fR modifier -is ignored for real values and on 64-bit platforms, which are always -converted as if the \fBl\fR modifier were present (i.e. the types -\fBdouble\fR and \fBlong\fR are used for the internal representation -of real and integer values, respectively). -If the \fBh\fR modifier is specified then integer values are truncated -to \fBshort\fR before conversion. Both \fBh\fR and \fBl\fR modifiers -are ignored on all other conversions. +For \fB%c\fR conversions the argument must be an integer value, +which will then be converted to the corresponding character value. +.IP [4] +The size modifiers are ignored when formatting floating-point values. +The \fBll\fR modifier has no \fBsprintf\fR counterpart. +The \fBb\fR specifier has no \fBsprintf\fR counterpart. .SH EXAMPLES +.PP +Convert the numeric value of a UNICODE character to the character +itself: +.PP +.CS +set value 120 +set char [\fBformat\fR %c $value] +.CE +.PP Convert the output of \fBtime\fR into seconds to an accuracy of hundredths of a second: +.PP .CS set us [lindex [time $someTclCode] 0] puts [\fBformat\fR "%.2f seconds to execute" [expr {$us / 1e6}]] .CE .PP Create a packed X11 literal color specification: +.PP .CS # Each color-component should be in range (0..255) set color [\fBformat\fR "#%02x%02x%02x" $r $g $b] @@ -227,15 +244,17 @@ set color [\fBformat\fR "#%02x%02x%02x" $r $g $b] Use XPG3 format codes to allow reordering of fields (a technique that is often used in localized message catalogs; see \fBmsgcat\fR) without reordering the data values passed to \fBformat\fR: +.PP .CS set fmt1 "Today, %d shares in %s were bought at $%.2f each" puts [\fBformat\fR $fmt1 123 "Global BigCorp" 19.37] -set fmt2 "Bought %2\\$s equity ($%3$.2f x %1\\$d) today" +set fmt2 "Bought %2\e$s equity ($%3$.2f x %1\e$d) today" puts [\fBformat\fR $fmt2 123 "Global BigCorp" 19.37] .CE .PP Print a small table of powers of three: +.PP .CS # Set up the column widths set w1 5 @@ -250,16 +269,17 @@ puts $sep # Print the contents of the table set p 1 for {set i 0} {$i<=20} {incr i} { - puts [\fBformat\fR "| %*d | %*ld |" $w1 $i $w2 $p] - set p [expr {wide($p) * 3}] + puts [\fBformat\fR "| %*d | %*ld |" $w1 $i $w2 $p] + set p [expr {wide($p) * 3}] } # Finish off by printing the separator again puts $sep .CE - .SH "SEE ALSO" scan(n), sprintf(3), string(n) - .SH KEYWORDS conversion specifier, format, sprintf, string, substitution +'\" Local Variables: +'\" mode: nroff +'\" End: |