Operator Precedence in C++

So far, we've seen a number of different operators. Here's a summary of the operators we've covered so far:

Boolean operators	&&, ||, !
Arithmetic operators	+, -, *, /, %
Equality operators	<, >, ==, <=, >=, !=
Assignment operators	=, +=, -=, *=, /=, %=

What is operator precedence?

Operator precedence refers to the order in which operators get used. An operator with high precedence will get used before an operator with lower precedence. Here's an example:

  int result = 4 + 5 * 6 + 2;

What will be the value of result? The answer depends on the precedence of the operators. In C++, the multiplication operator (*) has higher precedence than the addition operator (+). What that means is, the multiplication 5 * 6 will take place before either of the additions, so your expression will resolve to 4 + 30 + 2 , so result will store the value 36. Since C++ doesn't really care about whitespace, the same thing would be true if you had written:

  int result = 4+5 * 6+2;

The result would still be 36. Maybe you wanted to take the sum 4 + 5 and multiply it by the sum 6 + 2 for a result of 72? Just as in math class, add parentheses. You can write:

  int result = (4 + 5) * (6 + 2);

Operator precedence in C++

Operator precedence in C++ is incredibly easy! Don't let anyone tell you otherwise! Here's the trick: if you don't know the order of precedence, or you're not sure, add parentheses! Don't even bother looking it up. We can guarantee that it will be faster for you to add parentheses than to look it up in this tutorial or in a C++ book. Adding parentheses has another obvious benefit - it makes your code much easier to read. Chances are, if you are uncertain about the order of precedence, anyone reading your code will have the same uncertainty.
That having been said, here's the order of operator precedence. In general, the order is what you would think it is - that is, you can safely say

  int x = 4 + 3;

and it will correctly add 4 and 3 before assigning to x. Our advice is to read this table once and then never refer to it again.

Operator precedence
operators have the same precedence as other operators in their group, and higher precedence than operators in lower groups
operator	name
!	boolean not
*	multiplication
/	division
%	mod
+	addition
-	subtraction
<	is less than
<=	is less than or equal to
>	is greater than
>=	is greater than or equal to
==	is equal to
!=	is not equal to
&&	boolean and
||	boolean or
=	assignment
*=	multiply and assign
/=	divide and assign
%=	mod and assign
+=	add and assign
-=	subtract and assign