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RealInOut.md

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RealInOut

Floating-point I/O for PIM4 programs. Provides procedures to read and write REAL (single-precision) values in various output formats. For LONGREAL (double-precision) output, use SLongIO instead.

Available in PIM4 mode (the default). No special flags needed.

Variables

Variable Type Description
Done BOOLEAN Set by ReadReal. TRUE if a valid floating-point number was read from stdin, FALSE otherwise.

Procedures

PROCEDURE ReadReal(VAR r: REAL);

Read a floating-point number from stdin and store it in r. Accepts standard decimal notation (e.g., 3.14, -0.5, 1.0E10). Sets Done to FALSE if the input cannot be parsed as a number.

PROCEDURE WriteReal(r: REAL; w: CARDINAL);

Write r in general format (similar to C's %g), right-justified in a field of width w. The general format automatically chooses between fixed and scientific notation based on the magnitude of the number. Use w=1 for minimum-width output.

PROCEDURE WriteFixPt(r: REAL; w: CARDINAL; d: CARDINAL);

Write r in fixed-point format with exactly d digits after the decimal point, right-justified in width w. This is useful when you need a consistent number of decimal places (e.g., for currency or tabular output).

Example: WriteFixPt(3.14159, 10, 2) prints " 3.14".

PROCEDURE WriteRealOct(r: REAL);

Write r as a hexadecimal representation of its IEEE 754 bit pattern. This is a debugging aid, not a human-readable format.

Example

MODULE RealDemo;
FROM InOut IMPORT WriteString, WriteLn;
FROM RealInOut IMPORT WriteReal, WriteFixPt;
FROM MathLib IMPORT sqrt;

BEGIN
  WriteString("General:    ");
  WriteReal(sqrt(2.0), 12); WriteLn;

  WriteString("Fixed 2dp:  ");
  WriteFixPt(sqrt(2.0), 12, 2); WriteLn;

  WriteString("Fixed 6dp:  ");
  WriteFixPt(sqrt(2.0), 12, 6); WriteLn
END RealDemo.