Operator Precedence
In expressions like theseint y = c + a*b;It's important to know the precedence of operators. If you enter 5 x 6 + 7 in a calculator you'll get 37. If you enter 7 + 5 * 6 though you'll get 72 as it adds 7 to 5 first to get 12 then multiplies that by 6. (Not in the Windows accessory calculator though)
int x = d + e/f;
C++ is not as dependent upon the order of entry. It has preset precedence levels for it's operators. for expressions its easiest to pop things in brackets like this.
int y = c + (a*b);
int x = d + (e/f);
Table of Precedence Levels 1-4
The number indicates the levels, 1 is the highest and 18 the lowest. L-R means Left to right, R-L means Right to Left.
1 :: Scope resolution operator
1 (expression) Grouping
2 () L-R Function call
2 () Value construction, that is, type (expression)
2 [] Array subscript
2 -> Member operator (Indirect)
2 . Member operator (Direct)
2 const_cast Specialized cast
2 dynamic_cast Specialized cast
2 reinterpret_cast Specialized cast
2 static_cast Specialized cast
2 typeid Type identification
2 ++ Increment operator, postfix
2 -- Decrement operator, postfix
3 (all unary)
3 ! R-L Logical negation
3 ~ Bitwise negation
3 + Unary plus (positive sign)
3 - Unary minus (negative sign)
3 ++ Increment operator, prefix
3 -- Decrement operator, prefix
3 & Address
3 * Dereference (indirect value)
3 () Type cast, i.e. (type) expr
3 sizeof() Size in bytes
3 new Dynamically allocate storage
3 new [] Dynamically allocate array
3 delete Dynamically free storage
3 delete [] Dynamically free array
4 .* L-R Member dereference
4 ->* Indirect member dereference
Continued on the next page
