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diff --git a/upstream/archlinux/man1/perlnumber.1perl b/upstream/archlinux/man1/perlnumber.1perl new file mode 100644 index 00000000..3990d604 --- /dev/null +++ b/upstream/archlinux/man1/perlnumber.1perl @@ -0,0 +1,244 @@ +.\" -*- mode: troff; coding: utf-8 -*- +.\" Automatically generated by Pod::Man 5.01 (Pod::Simple 3.43) +.\" +.\" Standard preamble: +.\" ======================================================================== +.de Sp \" Vertical space (when we can't use .PP) +.if t .sp .5v +.if n .sp +.. +.de Vb \" Begin verbatim text +.ft CW +.nf +.ne \\$1 +.. +.de Ve \" End verbatim text +.ft R +.fi +.. +.\" \*(C` and \*(C' are quotes in nroff, nothing in troff, for use with C<>. +.ie n \{\ +. ds C` "" +. ds C' "" +'br\} +.el\{\ +. ds C` +. ds C' +'br\} +.\" +.\" Escape single quotes in literal strings from groff's Unicode transform. +.ie \n(.g .ds Aq \(aq +.el .ds Aq ' +.\" +.\" If the F register is >0, we'll generate index entries on stderr for +.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index +.\" entries marked with X<> in POD. Of course, you'll have to process the +.\" output yourself in some meaningful fashion. +.\" +.\" Avoid warning from groff about undefined register 'F'. +.de IX +.. +.nr rF 0 +.if \n(.g .if rF .nr rF 1 +.if (\n(rF:(\n(.g==0)) \{\ +. if \nF \{\ +. de IX +. tm Index:\\$1\t\\n%\t"\\$2" +.. +. if !\nF==2 \{\ +. nr % 0 +. nr F 2 +. \} +. \} +.\} +.rr rF +.\" ======================================================================== +.\" +.IX Title "PERLNUMBER 1perl" +.TH PERLNUMBER 1perl 2024-02-11 "perl v5.38.2" "Perl Programmers Reference Guide" +.\" For nroff, turn off justification. Always turn off hyphenation; it makes +.\" way too many mistakes in technical documents. +.if n .ad l +.nh +.SH NAME +perlnumber \- semantics of numbers and numeric operations in Perl +.SH SYNOPSIS +.IX Header "SYNOPSIS" +.Vb 7 +\& $n = 1234; # decimal integer +\& $n = 0b1110011; # binary integer +\& $n = 01234; # octal integer +\& $n = 0x1234; # hexadecimal integer +\& $n = 12.34e\-56; # exponential notation +\& $n = "\-12.34e56"; # number specified as a string +\& $n = "1234"; # number specified as a string +.Ve +.SH DESCRIPTION +.IX Header "DESCRIPTION" +This document describes how Perl internally handles numeric values. +.PP +Perl's operator overloading facility is completely ignored here. Operator +overloading allows user-defined behaviors for numbers, such as operations +over arbitrarily large integers, floating points numbers with arbitrary +precision, operations over "exotic" numbers such as modular arithmetic or +p\-adic arithmetic, and so on. See overload for details. +.SH "Storing numbers" +.IX Header "Storing numbers" +Perl can internally represent numbers in 3 different ways: as native +integers, as native floating point numbers, and as decimal strings. +Decimal strings may have an exponential notation part, as in \f(CW"12.34e\-56"\fR. +\&\fINative\fR here means "a format supported by the C compiler which was used +to build perl". +.PP +The term "native" does not mean quite as much when we talk about native +integers, as it does when native floating point numbers are involved. +The only implication of the term "native" on integers is that the limits for +the maximal and the minimal supported true integral quantities are close to +powers of 2. However, "native" floats have a most fundamental +restriction: they may represent only those numbers which have a relatively +"short" representation when converted to a binary fraction. For example, +0.9 cannot be represented by a native float, since the binary fraction +for 0.9 is infinite: +.PP +.Vb 1 +\& binary0.1110011001100... +.Ve +.PP +with the sequence \f(CW1100\fR repeating again and again. In addition to this +limitation, the exponent of the binary number is also restricted when it +is represented as a floating point number. On typical hardware, floating +point values can store numbers with up to 53 binary digits, and with binary +exponents between \-1024 and 1024. In decimal representation this is close +to 16 decimal digits and decimal exponents in the range of \-304..304. +The upshot of all this is that Perl cannot store a number like +12345678901234567 as a floating point number on such architectures without +loss of information. +.PP +Similarly, decimal strings can represent only those numbers which have a +finite decimal expansion. Being strings, and thus of arbitrary length, there +is no practical limit for the exponent or number of decimal digits for these +numbers. (But realize that what we are discussing the rules for just the +\&\fIstorage\fR of these numbers. The fact that you can store such "large" numbers +does not mean that the \fIoperations\fR over these numbers will use all +of the significant digits. +See "Numeric operators and numeric conversions" for details.) +.PP +In fact numbers stored in the native integer format may be stored either +in the signed native form, or in the unsigned native form. Thus the limits +for Perl numbers stored as native integers would typically be \-2**31..2**32\-1, +with appropriate modifications in the case of 64\-bit integers. Again, this +does not mean that Perl can do operations only over integers in this range: +it is possible to store many more integers in floating point format. +.PP +Summing up, Perl numeric values can store only those numbers which have +a finite decimal expansion or a "short" binary expansion. +.SH "Numeric operators and numeric conversions" +.IX Header "Numeric operators and numeric conversions" +As mentioned earlier, Perl can store a number in any one of three formats, +but most operators typically understand only one of those formats. When +a numeric value is passed as an argument to such an operator, it will be +converted to the format understood by the operator. +.PP +Six such conversions are possible: +.PP +.Vb 6 +\& native integer \-\-> native floating point (*) +\& native integer \-\-> decimal string +\& native floating_point \-\-> native integer (*) +\& native floating_point \-\-> decimal string (*) +\& decimal string \-\-> native integer +\& decimal string \-\-> native floating point (*) +.Ve +.PP +These conversions are governed by the following general rules: +.IP \(bu 4 +If the source number can be represented in the target form, that +representation is used. +.IP \(bu 4 +If the source number is outside of the limits representable in the target form, +a representation of the closest limit is used. (\fILoss of information\fR) +.IP \(bu 4 +If the source number is between two numbers representable in the target form, +a representation of one of these numbers is used. (\fILoss of information\fR) +.IP \(bu 4 +In \f(CW\*(C`native floating point \-\-> native integer\*(C'\fR conversions the magnitude +of the result is less than or equal to the magnitude of the source. +(\fI"Rounding to zero".\fR) +.IP \(bu 4 +If the \f(CW\*(C`decimal string \-\-> native integer\*(C'\fR conversion cannot be done +without loss of information, the result is compatible with the conversion +sequence \f(CW\*(C`decimal_string \-\-> native_floating_point \-\-> native_integer\*(C'\fR. +In particular, rounding is strongly biased to 0, though a number like +\&\f(CW"0.99999999999999999999"\fR has a chance of being rounded to 1. +.PP +\&\fBRESTRICTION\fR: The conversions marked with \f(CW\*(C`(*)\*(C'\fR above involve steps +performed by the C compiler. In particular, bugs/features of the compiler +used may lead to breakage of some of the above rules. +.SH "Flavors of Perl numeric operations" +.IX Header "Flavors of Perl numeric operations" +Perl operations which take a numeric argument treat that argument in one of +four different ways: they may force it to one of the integer, floating, or +string formats; or they may behave differently depending on the format of the +operand. Forcing a numeric value to a particular format does not change the +number stored in the value. +.PP +All the operators which need an argument in the integer format treat the +argument as in modular arithmetic, e.g., \f(CW\*(C`mod 2**32\*(C'\fR on a 32\-bit +architecture. \f(CW\*(C`sprintf "%u", \-1\*(C'\fR therefore provides the same result as +\&\f(CW\*(C`sprintf "%u", ~0\*(C'\fR. +.IP "Arithmetic operators" 4 +.IX Item "Arithmetic operators" +The binary operators \f(CW\*(C`+\*(C'\fR \f(CW\*(C`\-\*(C'\fR \f(CW\*(C`*\*(C'\fR \f(CW\*(C`/\*(C'\fR \f(CW\*(C`%\*(C'\fR \f(CW\*(C`==\*(C'\fR \f(CW\*(C`!=\*(C'\fR \f(CW\*(C`>\*(C'\fR \f(CW\*(C`<\*(C'\fR +\&\f(CW\*(C`>=\*(C'\fR \f(CW\*(C`<=\*(C'\fR and the unary operators \f(CW\*(C`\-\*(C'\fR \f(CW\*(C`abs\*(C'\fR and \f(CW\*(C`\-\-\*(C'\fR will +attempt to convert arguments to integers. If both conversions are possible +without loss of precision, and the operation can be performed without +loss of precision then the integer result is used. Otherwise arguments are +converted to floating point format and the floating point result is used. +The caching of conversions (as described above) means that the integer +conversion does not throw away fractional parts on floating point numbers. +.IP ++ 4 +\&\f(CW\*(C`++\*(C'\fR behaves as the other operators above, except that if it is a string +matching the format \f(CW\*(C`/^[a\-zA\-Z]*[0\-9]*\ez/\*(C'\fR the string increment described +in perlop is used. +.ie n .IP "Arithmetic operators during ""use integer""" 4 +.el .IP "Arithmetic operators during \f(CWuse integer\fR" 4 +.IX Item "Arithmetic operators during use integer" +In scopes where \f(CW\*(C`use integer;\*(C'\fR is in force, nearly all the operators listed +above will force their argument(s) into integer format, and return an integer +result. The exceptions, \f(CW\*(C`abs\*(C'\fR, \f(CW\*(C`++\*(C'\fR and \f(CW\*(C`\-\-\*(C'\fR, do not change their +behavior with \f(CW\*(C`use integer;\*(C'\fR +.IP "Other mathematical operators" 4 +.IX Item "Other mathematical operators" +Operators such as \f(CW\*(C`**\*(C'\fR, \f(CW\*(C`sin\*(C'\fR and \f(CW\*(C`exp\*(C'\fR force arguments to floating point +format. +.IP "Bitwise operators" 4 +.IX Item "Bitwise operators" +Arguments are forced into the integer format if not strings. +.ie n .IP "Bitwise operators during ""use integer""" 4 +.el .IP "Bitwise operators during \f(CWuse integer\fR" 4 +.IX Item "Bitwise operators during use integer" +forces arguments to integer format. Also shift operations internally use +signed integers rather than the default unsigned. +.IP "Operators which expect an integer" 4 +.IX Item "Operators which expect an integer" +force the argument into the integer format. This is applicable +to the third and fourth arguments of \f(CW\*(C`sysread\*(C'\fR, for example. +.IP "Operators which expect a string" 4 +.IX Item "Operators which expect a string" +force the argument into the string format. For example, this is +applicable to \f(CW\*(C`printf "%s", $value\*(C'\fR. +.PP +Though forcing an argument into a particular form does not change the +stored number, Perl remembers the result of such conversions. In +particular, though the first such conversion may be time-consuming, +repeated operations will not need to redo the conversion. +.SH AUTHOR +.IX Header "AUTHOR" +Ilya Zakharevich \f(CW\*(C`ilya@math.ohio\-state.edu\*(C'\fR +.PP +Editorial adjustments by Gurusamy Sarathy <gsar@ActiveState.com> +.PP +Updates for 5.8.0 by Nicholas Clark <nick@ccl4.org> +.SH "SEE ALSO" +.IX Header "SEE ALSO" +overload, perlop |