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Digital Research
2020-11-06 18:50:37 +01:00

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.so macro
.he 'PRINTF''PRINTF'
.n NAME PRINTF
printf - formatted print
.sy SYNOPSIS
printf(plist);
char *plist;
.d DESCRIPTION
\&'printf' takes the input string and interprets various formatting
commands and outputs the results to the standard output device.
There are two types of items in the input string: characters which
are copied literally and format statements which work on strings,
characters and numerics.
.sp
The string takes the form of a literal string with embedded format
statements and the various arguments on which the format statements
act: printf("...",arg1,arg2...).
All format statements are
preceded by a percent sign and terminated by one of the conversion
characters.
Between the percent sign and the conversion characters
are optional symbols which adjust the standard formats.
.sp
The format statement consists of a contiguous group of characters.
A minus sign '-' may follow the percent sign to designate that the
item is to be left justified.
A decimal number designating the field width may optionally be specified.
If the item is larger than the specified width it will be printed as is.
If the item is smaller,
the item will be padded with spaces.
If the first digit of the specified width is a '0' then the item
will be padded with zero's instead of spaces.
If the item is a string or
a floating point number a second field preceded by a period '.'
may be specified.
The second width field specifies the number of
digits to the right of the decimal point in the case of a floating
point and the maximum number of characters to be printed in the
case of a string.
.sp
The last item of a format statement describes the item we are
formatting.
They are 'c', 'd', 'e', 'f', 'u', 'o', 's', and 'x'.
.sp
.in +6
.ti -7
\ 'c'\ \ \ The argument to be printed is a single character.
.sp
.ti -7
\ 's'\ \ \ The argument is a string or character pointer.
All characters will be printed unless a maximum width field is in force.
.sp
.ti -7
\ 'd'\ \ \ The argument is a decimal numeric.
.sp
.ti -7
\ 'o'\ \ \ The argument is a octal numeric.
.sp
.ti -7
\ 'x'\ \ \ The argument is a hexidecimal numeric.
.sp
.ti -7
\ 'u'\ \ \ The argument will be interpreted as an unsigned decimal
integer in the range 0 to 65535.
.sp
.ti -7
\ 'f'\ \ \ The argument is either a floating point or double precision
number.
It will be of the form: an optional minus sign, digits,
a decimal point, and more digits.
If no second width field has
been specified there will be six digits to the right of the decimal point.
.sp
.ti -7
\ 'e'\ \ \ The argument is to be printed in scientific notation and is
either a floating point or double precision number.
The format is
exactly like the 'f' format except that only one digit is to the
right of the decimal point and a two digit exponent is specified after
the number.
.sp
Format descriptors 'd', 'o', 'x', and 'u' may optionally be preceeded
by a 'l' character to specify that the argument to be printed is a
long rather than an integer.
.sp
Any other character following a percent sign will be taken as a
literal and will itself be printed.
In this way you can print a percent sign or a double quote.
.sp