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F.3 Edited Output for Decimal Types

  1. The child packages Text_IO.Editing and Wide_Text_IO.Editing provide localizable formatted text output, known as edited output , for 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:
    1. the currency string;
    2. the digits group separator character;
    3. the radix mark character; and
    4. the fill character that replaces leading zeros of the numeric value.

  1. 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, respectively.
  2. Each of the locale elements has a default value that can be replaced or explicitly overridden.
  3. 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.
  4. 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: 
  5. Decimal Digit:      '9'
Radix Control:      '.'  'V'
Sign Control:       '+'  '-'  '<'  '>'  "CR"  "DB"
Currency Control:   '$'  '#'
Zero Suppression:   'Z'  '*'
Simple Insertion:   '_'  'B'  '0'  '/'
  6. The entries are not case-sensitive. Mixed- or lower-case forms for "CR" and "DB", and lower-case forms for 'V', 'Z', and 'B', have the same effect as the upper-case symbols shown.
  7. An occurrence of a '9' Character in the picture String represents a decimal digit position in the edited output string.
  8. A radix control Character in the picture String indicates the position of the radix mark in the edited output string: an actual character position for '.', or an assumed position for 'V'.
  9. A sign control Character in the picture String affects the form of the sign in the edited output string. The '<' and '>' Character values indicate parentheses for negative values. A Character '+', '-', or '<' appears either singly, signifying a fixed-position sign in the edited output, or repeated, signifying a floating-position sign that is preceded by zero or more space characters and that replaces a leading 0.
  10. A currency control Character in the picture String indicates an occurrence of the currency string in the edited output string. The '$' 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.
  11. 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 '*').
  12. 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 suppression string.
  13. 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 character.
  14. The generic packages Text_IO.Decimal_IO and Wide_Text_IO.Decimal_IO, See section A.10.9 Input-Output for Real Types, provide text input and non-edited text output for decimal types.

    NOTES

  15. (2) A picture String is of type Standard.String, both for Text_IO.Editing and Wide_Text_IO.Editing.

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