11.3.3  Printf Sprintf Fprintf Format Strings

Mythryl supports the following basic format specifiers:

• %i Decimal integer.
• %o Octal integer.
• %x Hexadecimal integer, lowercase letters.
• %X Hexadecimal integer, uppercase letters.
• %b Binary integer.
• %e Float, exponential format, lowercase ’e’.
• %E Float, exponential format, uppercase ’e’.
• %f Float, fixed format.
• %G Float, general format, uppercase ’e’.
• %g Float, general format, lowercase ’e’.
• %c Character value.
• %B Boolean value.

Zero or more of following modifiers may follow the percent in a format specifier:

• ’ ’ Print a leading blank on positive numbers.
• ’+’ Print a leading plus on positive numbers.
• ’ ’ Print a leading tilda (instead of hyphen) on negative numbers.
• ’-’ Left-justify (strings) or print negative numbers with a leading hyphen (numbers).
• ’#’ Base.
• ’0’ Zero-pad (instead of blank-padding).

A decimal field width is allowed after the above modifiers (if any).

In the case of the floating point specifiers (that is, ’E’, ’e’, ’f’, ’G’, ’g’), the width field may be followed by a decimal point and a decimal precision.

No other format specifiers or modifiers are currently supported.

Integer types other than Int must currently be converted to string form using other facilities, typically the to_string function in the relevant package or else the underlying sfprintf package.

(Mapping of basic format specifiers to meaning is done in src/lib/src/printf-field.pkg.)

Examples:

eval:  printf "%12s\n" "foo";
         foo

eval:  printf "%-12s\n" "foo";
foo         

eval:  printf "%12s%12s\n" "foo" "bar";
         foo         bar

eval:  printf "%-12s%-12s\n" "foo" "bar";
foo         bar         

eval:  printf "%B\n" ("foo"=="bar");
FALSE

eval:  printf "%f\n" pi;
3.141593

eval:  printf "%g\n" pi;
3.14159

eval:  printf "%e\n" pi;
3.141593e00

eval:  printf "%E\n" pi;
3.141593E00

eval:  printf "%15.7g\n" pi;
       3.141593

eval:  printf "%15.10g\n" pi;
    3.141592654

eval:  printf "%f\n" (pi*1000.0*1000.0);
3141592.653590

eval:  printf "%g\n" (pi*1000.0*1000.0);
3.14159e06

eval:  sprintf "%g\n" (pi*1000.0*1000.0);
"3.14159e06\n"