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F.3 Edited Output for Decimal Types
The child packages
Text_IO.Editing and Wide_Text_IO.Editing provide localizable formatted
text output, known as edited output
decimal types. An edited output string is a function of a numeric value,
program-specifiable locale elements, and a format control value. The
numeric value is of some decimal type. The locale elements are:
- the digits group separator character;
- the radix mark character; and
- the fill character that replaces leading
zeros of the numeric value.
For Text_IO.Editing the edited output and currency
strings are of type String, and the locale characters are of type Character.
For Wide_Text_IO.Editing their types are Wide_String and Wide_Character,
Each of the locale elements has a default value
that can be replaced or explicitly overridden.
A format-control value is of the private type
Picture; it determines the composition of the edited output string and
controls the form and placement of the sign, the position of the locale
elements and the decimal digits, the presence or absence of a radix mark,
suppression of leading zeros, and insertion of particular character values.
A Picture object
is composed from a String value, known as a picture String, that
serves as a template for the edited output string, and a Boolean value
that controls whether a string of all space characters is produced when
the number's value is zero. A picture String comprises a sequence of
one- or two-Character symbols, each serving as a placeholder for a character
or string at a corresponding position in the edited output string. The
picture String symbols fall into several categories based on their effect
on the edited output string:
Decimal Digit: '9'
Radix Control: '.' 'V'
Sign Control: '+' '-' '<' '>' "CR" "DB"
Currency Control: '$' '#'
Zero Suppression: 'Z' '*'
Simple Insertion: '_' 'B' '0' '/'
The entries are not case-sensitive. Mixed- or
lower-case forms for "CR" and "DB", and lower-case
forms for 'V', 'Z', and 'B', have the same effect as the upper-case symbols
An occurrence of a '9' Character in the picture
String represents a decimal digit position in the edited output string.
A radix control Character in the picture String
indicates the position of the radix mark in the edited output string:
an actual character position for '.', or an assumed position for 'V'.
A sign control Character in the picture String
affects the form of the sign in the edited output string. The '<'
and '>' Character values indicate parentheses for negative values.
A Character '+', '-', or '<' appears either singly, signifying a fixed-position
sign in the edited output, or repeated, signifying a floating-position
sign that is preceded by zero or more space characters and that replaces
a leading 0.
A currency control Character in the picture String
indicates an occurrence of the currency string in the edited output string.
The '$' Character represents the complete currency string; the '#' Character
represents one character of the currency string. A '$' Character appears
either singly, indicating a fixed-position currency string in the edited
output, or repeated, indicating a floating-position currency string that
occurs in place of a leading 0. A sequence of '#' Character values indicates
either a fixed- or floating-position currency string, depending on context.
A zero suppression Character in the picture String
allows a leading zero to be replaced by either the space character (for
'Z') or the fill character (for '*').
A simple insertion Character in the picture String
represents, in general, either itself (if '/' or '0'), the space character
(if 'B'), or the digits group separator character (if '_'). In some contexts
it is treated as part of a floating sign, floating currency, or zero
An example of a picture String is "<###Z_ZZ9.99>".
If the currency string is "FF", the separator character is
',', and the radix mark is '.' then the edited output string values for
the decimal values 32.10 and -5432.10 are "bbFFbbb32.10b" and
"(bFF5,432.10)", respectively, where 'b' indicates the space
The generic packages Text_IO.Decimal_IO and Wide_Text_IO.Decimal_IO
for Real Types
'') provide text input and non-edited text output for
2 A picture String is of
type Standard.String, both for Text_IO.Editing and Wide_Text_IO.Editing.
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