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There are several operators available in Structured Text language:
Operation 
Symbol 
Precedence 
Parenthesization 
(expression) 
Highest 
Negation Complement 
 ! 

Multiply Divide Modulo 
* / % 

Add Subtract 
+  

Left Shift Right Shift 
<< >> 

Comparison 
<, >, <=, >=,==,!= 

Boolean AND Boolean OR Boolean XOR 
&  ^ 
Lowest 
All the operators in the table above are sorted after precedence. This is also called order of operations, and you may know about if from mathematics.The order of operations is the order in which the operations are executed or calculated. Just take a look at this expression:
A + B * C
How will this expression be evaluated by the compiler? There are two operations left: multiply and addition. But since multiply has a higher precedence, that will be the ﬁrst to be evaluated. B * C comes ﬁrst and then the result is added to A. Every time an expression is evaluated, the evaluation follows the order of precedence as in the table above.
The operators used for expressions in Structured Text can be divided into four groups. Each group of operators will have its speciﬁc function and will yield a speciﬁc data type: