| Server IP : 134.29.175.74 / Your IP : 216.73.216.160 Web Server : nginx/1.10.2 System : Windows NT CST-WEBSERVER 10.0 build 19045 (Windows 10) i586 User : Administrator ( 0) PHP Version : 7.1.0 Disable Function : NONE MySQL : OFF | cURL : ON | WGET : OFF | Perl : OFF | Python : OFF | Sudo : OFF | Pkexec : OFF Directory : C:/Windows/System32/WindowsPowerShell/v1.0/en-US/ |
Upload File : |
ABOUT OPERATOR PRECEDENCE
SHORT DESCRIPTION
Lists the PowerShell operators in precedence order.
LONG DESCRIPTION
PowerShell operators let you construct simple, but powerful expressions.
This topic lists the operators in precedence order. Precedence order is the
order in which PowerShell evaluates the operators when multiple operators
appear in the same expression.
When operators have equal precedence, PowerShell evaluates them from left
to right as they appear within the expression. The exceptions are the
assignment operators, the cast operators, and the negation operators (!,
-not, -bnot), which are evaluated from right to left.
You can use enclosures, such as parentheses, to override the standard
precedence order and force PowerShell to evaluate the enclosed part of an
expression before an unenclosed part.
In the following list, operators are listed in the order that they are
evaluated. Operators on the same line, or in the same group, have equal
precedence.
The Operator column lists the operators. The Reference column lists the
PowerShell Help topic in which the operator is described. To display the
topic, type get-help <topic-name>.
OPERATOR REFERENCE
------------------------ ----------------------------
$() @() () about_Operators
. (member access) about_Operators
:: (static) about_Operators
[0] (index operator) about_Operators
[int] (cast operators) about_Operators
-split (unary) about_Split
-join (unary) about_Join
, (comma operator) about_Operators
++ -- about_Assignment_Operators
! -not about_Logical_Operators
.. (range operator) about_Operators
-f (format operator) about_Operators
- (unary/negative) about_Arithmetic_Operators
* / % about_Arithmetic_Operators
+ - about_Arithmetic_Operators
The following group of operators have equal precedence. Their
case-sensitive and explicitly case-insensitive variants have the same
precedence.
OPERATOR REFERENCE
------------------------- ----------------------------
-split (binary) about_Split
-join (binary) about_Join
-is -isnot -as about_Type_Operators
-eq -ne -gt -gt -lt -le about_Comparison_Operators
-like -notlike about_Comparison_Operators
-match -notmatch about_Comparison_Operators
-in -notIn about_Comparison_Operators
-contains -notContains about_Comparison_Operators
-replace about_Comparison_Operators
The list resumes here with the following operators in precedence order:
OPERATOR REFERENCE
------------------------ ----------------------------
-band -bnot -bor -bxor about_Arithmetic_Operators
-and -or -xor about_Logical_Operators
The following items are not true operators. They are part of PowerShell's
command syntax, not expression syntax. Assignment is always the last action
that happens.
SYNTAX REFERENCE
----------------------- ----------------------------
. (dot-source) about_Operators
& (call) about_Operators
| (pipeline operator) about_Operators
> >> 2> 2>> 2>&1 about_Redirection
= += -= *= /= %= about_Assignment_Operators
EXAMPLES
The following two commands show the arithmetic operators and the effect of
using parentheses to force PowerShell to evaluate the enclosed part of the
expression first.
PS> 2 + 3 * 4
14
PS> (2 + 3) * 4
20
The following example gets the read-only text files from the local
directory and saves them in the $read_only variable.
$read_only = Get-ChildItem *.txt | Where-Object {$_.isReadOnly}
It is equivalent to the following example.
$read_only = ( Get-ChildItem *.txt | Where-Object {$_.isReadOnly} )
Because the pipeline operator (|) has a higher precedence than the
assignment operator (=), the files that the Get-ChildItem cmdlet gets are
sent to the Where-Object cmdlet for filtering before they are assigned to
the $read_only variable.
The following example demonstrates that the index operator takes precedence
over the cast operator.
This expression creates an array of three strings. Then, it uses the index
operator with a value of 0 to select the first object in the array, which
is the first string. Finally, it casts the selected object as a string. In
this case, the cast has no effect.
PS> [string]@('Windows','PowerShell','2.0')[0]
Windows
This expression uses parentheses to force the cast operation to occur
before the index selection. As a result, the entire array is cast as a
(single) string. Then, the index operator selects the first item in the
string array, which is the first character.
PS> ([string]@('Windows','PowerShell','2.0'))[0]
W
In the following example, because the -gt (greater-than) operator has a
higher precedence than the -and (logical AND) operator, the result of the
expression is FALSE.
PS> 2 -gt 4 -and 1
False
It is equivalent to the following expression.
PS> (2 -gt 4) -and 1
False
If the -and operator had higher precedence, the answer would be TRUE.
PS> 2 -gt (4 -and 1)
True
However, this example demonstrates an important principle of managing
operator precedence. When an expression is difficult for people to
interpret, use parentheses to force the evaluation order, even when it
forces the default operator precedence. The parentheses make your
intentions clear to people who are reading and maintaining your scripts.
SEE ALSO
about_Operators
about_Assignment_Operators
about_Comparison_Operators
about_Arithmetic_Operators
about_Join
about_Redirection
about_Scopes
about_Split
about_Type_Operators