Mikroelektronika MIKROE-738 Datenbogen

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MikroElektronika

Unlike  many  other  programming  languages,  C  treats  value  assignment  as  operation  (represented  by  an  operator) 

rather than instruction.

Simple Assignment Operator

For a common value assignment, a simple assignment operator (

=

) is used:

The 

 is an object (memory location) to which the value of 

 is assigned. Operand 

 

has to be lvalue and 

 can be any expression. The assignment expression itself is not lvalue.

If 

 and 

 are of different types, the result of the 

 will be converted to the type 

of 

, if necessary. Refer to Type Conversions for more information.

Compound Assignment Operators

C allows more comlex assignments by means of compound assignment operators. The syntax of compound assignment 

operators is:

where 

 can be one of binary operators 

+, -, *, /, %, &, |, ^, <<

, or

 >>.

Thus, we have 10 different compound assignment operators:

 +=

,

 -=

,

 *=

,

 /=

,

 %=

,

 &=

,

 |=

,

 ^=

,

 <<= 

and

 >>=

. All 

of them associate from right to left. Spaces separating compound operators (e.g. 

+ =

) will generate error.

Compound assignment has the same effect as

except the lvalue 

 is evaluated only once. For example, 

 += 

 is the same 

as 

 = 

 + 

.

Assignment Rules

For both simple and compound assignment, the operands 

 and 

 must obey one of the 

following rules:

 

1. 

 is of qualified or unqualified arithmetic type and 

 is of arithmetic type. 

 

2. 

 has a qualified or unqualified version of structure or union type compatible with the type of  

 

    

. 

 

3. 

 and 

 are pointers to qualified or unqualified versions of compatible types  

 

    and the type pointed to by left has all qualifiers of the type pointed to by right.