Syntax
The
-f operator is a binary operator with the format string on the left side and the values (
array) to be formatted on its right side:
'format string' -f array
In the format string, curly braces denote the locations where the elements of the array will be formatted.
In the simplest form, such curly braces contain the index of the element in the array that will be formatted. Note: in the following example, the second element is printed first with other two elements following:
PS C:\> '{2} {0} {1}' -f 'zero', 'one', 'two'
two zero one
Specifing width and alignment
The width of the formatted string can be controlled by separating the position number from the width by a comma. This allows for nicely formatted tables with numbers:
foreach ($i in 5,111,71) {
foreach ($j in 42,321, 9) {
'{0,3} * {1,3} = {2,5}' -f ($i, $j, ($i*$j))
}}
5 * 42 = 210
5 * 321 = 1605
5 * 9 = 45
111 * 42 = 4662
111 * 321 = 35631
111 * 9 = 999
71 * 42 = 2982
71 * 321 = 22791
71 * 9 = 639
In order to left align a value, the width needs to be prepended by a minus sign:
foreach ($i in ('five', 5), ('forty-two', 42), ('three', 3)) {
' {1,2}: {0,-9}' -f $i
}
5: five
42: forty-two
3: three
A
formatting instruction can be given with the colon. For example,
:x formats a number as hexadecimal (compare with
format-hex). Formatting instructions can be specified with or without a width:
(3,255,2048).foreach( { '{0,3:x} = {0,4} | {0:x} = {0}' -f $_ } )
3 = 3 | 3 = 3
ff = 255 | ff = 255
800 = 2048 | 800 = 2048
Leading zeros can be specified as follows
(1,23,456,7890).forEach( { '{0,6:00000}' -f $_ } )
00001
00023
00456
07890
Alternatively, leading zeroes can also be specified by indicating the desired number of places (here: 5) after the formatting instruction (here: d):
(1,23,456,7890).forEach( { '{0,6:d5}' -f $_ } )
00001
00023
00456
07890
When formatting hexadecimal numbers, it is x followed by the maximum width to be filled with zeroes:
'{0,4:x4} {1,4:x4}' -f 1024, 4095
0400 0fff
Positional arguments and alignment
The following script demonstrates the positional arguments and alignment:
echo ("0: {0} - 2:{2} - 1: {1}" -f 'zero', 'one', 'two')
#
# 0: zero - 2:two - 1: one
#
# {x, n) right aligns the xth element with n places
#
# {x,-n) left aligns the xth element with n places
#
forEach ($item in ('five', 5), ('a hundred', 100), ('two', 2), ('forty-two', 42) ) {
echo ("{0,-10}: {1,3}" -f $item[0], $item[1])
}
#
# five : 5
# a hundred : 100
# two : 2
# forty-two : 42