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><DIV
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><H1
><A
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>Chapter 11. Operators</A
></H1
><DIV
CLASS="TOC"
><DL
><DT
><B
>Table of Contents</B
></DT
><DT
><A
HREF="language.operators.html#language.operators.precedence"
>Operator Precedence</A
></DT
><DT
><A
HREF="language.operators.arithmetic.html"
>Arithmetic Operators</A
></DT
><DT
><A
HREF="language.operators.assignment.html"
>Assignment Operators</A
></DT
><DT
><A
HREF="language.operators.bitwise.html"
>Bitwise Operators</A
></DT
><DT
><A
HREF="language.operators.comparison.html"
>Comparison Operators</A
></DT
><DT
><A
HREF="language.operators.errorcontrol.html"
>Error Control Operators</A
></DT
><DT
><A
HREF="language.operators.execution.html"
>Execution Operators</A
></DT
><DT
><A
HREF="language.operators.increment.html"
>Incrementing/Decrementing Operators</A
></DT
><DT
><A
HREF="language.operators.logical.html"
>Logical Operators</A
></DT
><DT
><A
HREF="language.operators.string.html"
>String Operators</A
></DT
><DT
><A
HREF="language.operators.array.html"
>Array Operators</A
></DT
></DL
></DIV
><P
> </P
><DIV
CLASS="sect1"
><H1
CLASS="sect1"
><A
NAME="language.operators.precedence"
></A
>Operator Precedence</H1
><P
> The precedence of an operator specifies how "tightly" it binds two
expressions together. For example, in the expression <TT
CLASS="literal"
>1 +
5 * 3</TT
>, the answer is <TT
CLASS="literal"
>16</TT
> and not
<TT
CLASS="literal"
>18</TT
> because the multiplication ("*") operator
has a higher precedence than the addition ("+") operator.
Parentheses may be used to force precedence, if necessary. For
instance: <TT
CLASS="literal"
>(1 + 5) * 3</TT
> evaluates to
<TT
CLASS="literal"
>18</TT
>.
</P
><P
> The following table lists the precedence of operators with the
lowest-precedence operators listed first.
<DIV
CLASS="table"
><A
NAME="AEN4396"
></A
><P
><B
>Table 11-1. Operator Precedence</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><THEAD
><TR
><TH
ALIGN="LEFT"
VALIGN="MIDDLE"
>Associativity</TH
><TH
ALIGN="LEFT"
VALIGN="MIDDLE"
>Operators</TH
></TR
></THEAD
><TBODY
><TR
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>left</TD
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>,</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>left</TD
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>or</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>left</TD
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>xor</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>left</TD
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>and</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>right</TD
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>print</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>left</TD
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
> = += -= *= /= .= %= &= |= ^= ~= <<= >>=
</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>left</TD
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>? :</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>left</TD
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>||</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>left</TD
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>&&</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>left</TD
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>|</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>left</TD
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>^</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>left</TD
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>&</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>non-associative</TD
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>== != === !==</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>non-associative</TD
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>< <= > >=</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>left</TD
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
><< >></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>left</TD
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>+ - .</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>left</TD
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>* / %</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>right</TD
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>! ~ ++ -- (int) (float) (string) (array) (object) @</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>right</TD
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>[</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>non-associative</TD
><TD
ALIGN="LEFT"
VALIGN="MIDDLE"
>new</TD
></TR
></TBODY
></TABLE
></DIV
>
</P
><DIV
CLASS="note"
><BLOCKQUOTE
CLASS="note"
><P
><B
>Note: </B
>
Although <TT
CLASS="literal"
>!</TT
> has a higher precedence than
<TT
CLASS="literal"
>=</TT
>, PHP will still allow expressions
similar to the following: <TT
CLASS="literal"
>if (!$a = foo())</TT
>,
in which case the output from <TT
CLASS="literal"
>foo()</TT
> is
put into <TT
CLASS="varname"
>$a</TT
>.
</P
></BLOCKQUOTE
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