Displaying other output

 

Syntax

BD>print : This is some text, followed by the value of this constant: %fred is (%fred)

BD>print : This will not throw a carriage-return or line-feed $

The PRINT:  command is used to output information to the screen: headings, titles, general information, and various numerical values. It has a special status in [B/D] as the argument to the print: command is not parsed in the same way as most of the other [B/D] commands. In fact parsing is limited to the following exceptions.

• Regarding the substitution of quantities in square brackets: the program first checks active string and for lists, and makes any substitutions for strings and control variables as necessary. Otherwise the quantity is printed as is.
• Material found inside round brackets is assumed to represent a valid [B/D] equation whose value is to be printed. Thus, the syntax

  BD>print : text1 (E) text2

  is used to evaluate the value of the equation E, and to print this value after text1 and before text2. Prior to the determination of the equation, the text between the round brackets is parsed in the usual way to remove redundant spaces, turn text to lower case, and make any necessary substitutions for strings and control variables. The value is output with a minimum width set by the fwidth  control, and to the number of decimal places specified by the dplaces  control.

• You may wish to include the round brackets symbols as ordinary text. This is in any case possible for the closing round bracket symbol. For the opening round bracket symbol, this is achieved by prefixing it by the " symbol. Any character succeeding a " symbol is printed literally. (So to output the " symbol, you must use two side by side.) Examples are:

  BD>print : (3+2) is an equation "(but this is not),

  which should produce the text ``5.0000 is an equation (but this is not)'',

  and

  BD>print : ""See how we produce quotation marks"".

Otherwise, redundant spaces are not removed from the text in the PRINT:  command, and the case of the text is not changed. This allows us to format text output nicely, capitalising wherever we want, and so forth.

The second form of the syntax, where the text following the command is terminated by the `$' symbol, supresses the carriage return and linefeed usually output. This allows text from different PRINT:  statements to be output on the same line, as in the following example:

BD>print : Beware the $

BD>if : %x | print : dog! | else : | print : ides of March!

where might be some constant taking values zero or one.