What are the most important C++ operators?
C++ operators are essential for programming with C++. Whether you are just beginning to learn C++ or have been working with the programming language for a while, operators can make programming simpler and more efficient. The function of some operators can be deduced from their name, while others may take some time to memorize.
What are C++ operators?
An operator is a sign for an operation, which is applied to at least one operand, but in most cases to several. This results in a new value in most cases. A popular example of these are the arithmetic operators you learn in school, for example, “+” for addition and “-” for subtraction.
C++ operators are not only distinguishable according to their functional purpose. The operator’s arity is also an important criterion:
| Arity | Number of operands | Example |
|---|---|---|
| Unary operators | One operand | Logical negation: !var_name
|
| Binary operators | Two operand | Addition: value1 + value2
|
| Ternary operators | Three operands | If-else-condition: condition? condition_true : condition_false
|
What is operator precedence?
As with arithmetic operators in school or Python operators, there is an operator precedence for C++ operators. This specifies the order in which the operators should be evaluated. The dot before dash rule applies for arithmetic operators, however, there are other rules for other C++ operators.
if (var1 && var2 || var3) {
do_something();
}
The example above shows the logical expression being evaluated after the if operator. The && operator (logical And) has priority over the || operator (logical Or). So, if the evaluation of “var1 && var2” or the evaluation of “var3” returns “true”, the “do_something()” function call is executed.
You can also use brackets to be on the safe side.
How to overload C++ operators
You can overload most C++ operators. This means that you can assign a new meaning to an existing operator in a context. To perform an operator overload in C++, you need the keyword “operator”. When overloading, this keyword should be put before the C++ operator. Operator overloading in C++ will behave like function overloading.
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An overview of C++ operators
Arithmetic operators
You probably already know the arithmetic C++ operators from school. They operate on numbers and return a new number. The arithmetic operators are all binary operators, except for the unary plus and unary minus.
| C++ operator | Meaning | Example |
|---|---|---|
+
|
Addition / unary plus | 6 + 4
|
-
|
Subtraction / unary minus | 10 - 6
|
*
|
Multiplication | 10 * 3
|
/
|
Integer division | 20 / 10
|
%
|
Modulo | 21 % 2
|
Assignment operators
Similar to other programming languages, values are stored in variables. You need special operators to assign concrete values to these variables.
Simple assignment operators
| C++ operator | Meaning | Example |
|---|---|---|
=
|
Simple assignment | x = 3
|
++
|
Increment | x++
|
--
|
Decrement | x--
|
Combined assignment operators
In addition to the simple assignment operators, C++ also supports combined operators. These are arithmetic or bitwise operations which are simultaneously combined with a value assignment:
int x = 4;
x += 2;
The code example above shows that the variable x assigned the numeric value 4 with a simple assignment. The combined assignment operator “+=” is used to perform an arithmetic addition after this and saves the resulting value directly in x. The assignment would be “x = x + 2” after being written out.
| C++ operator | Meaning | Example |
|---|---|---|
+=
|
Addition and assignment | x += 2
|
-=
|
Subtraction and assignment | x -= 2
|
*=
|
Multiplication and assignment | x *= 2
|
/=
|
Division and assignment | x /= 2
|
%=
|
Modulo and assignment | x %= 2
|
&=
|
Bitwise And and assignment | b &= 1
|
<<=
|
Bitshift left and assignment | b <<= 1
|
>>=
|
Bitshift right and assignment | b >>= 1
|
| ^= | Bitwise Xor and assignment | b ^= 1
|
| ` | =` | Bitwise Or and assignment |
Logical C++ operators
You can use the C++ logical operators for propositional comparisons of two expressions. Logical operators are binary, except for the Logical Not, which only refers to one statement and negates its truth value.
| C++ operator | Meaning | Example |
|---|---|---|
&&
|
Logical And | true && true
|
| ` | ` | |
!
|
Logical Not | !true
|
Comparison operators
Comparison operators are C++ operators that examine the relationship between two elements. They are binary, except for the three-way comparison, which returns a number. The return value of all C++ comparison operators is a truth value.
| C++ operator | Meaning | Example |
|---|---|---|
==
|
Equality | a == b
|
!=
|
Inequality | a != b
|
<=
|
Smaller or equal | a <= b
|
>=
|
Greater or equal | a >= b
|
<
|
Smaller | a < b
|
>
|
Larger | a > b
|
<=>
|
Three-way comparison | a <=> b
|
Bit manipulation
Bitwise C++ operators access individual bits efficiently and improve the speed of programs. They are especially important for performance-oriented programming.
| C++ operator | Meaning | Example |
|---|---|---|
&
|
Bitwise And | a & b
|
| ` | ` | Bitwise Or |
^
|
Bitwise Xor | a ^ b
|
~
|
Bitwise negation | ~a
|
<<
|
Left shift | a << b
|
>>
|
Right shift | a >> b
|
Memory management
C++ is a machine-oriented language and has a several operators for memory management.
| C++ operator | Meaning | Example |
|---|---|---|
&
|
Address determination | &x
|
sizeof()
|
Determines the memory requirement of an expression | sizeof(x)
|
new
|
Creates a new object and returns pointer | object* pointer = new object()
|
delete
|
Destroys an object | delete object
|
Data access for objects and pointers
The following C++ operators will help you access individual members of objects or the memory areas of pointers.
| C++ operator | Meaning | Example |
|---|---|---|
*
|
Dereferencing pointers, returns memory area | *pointer = 3;
|
.
|
Accesses members of an object | object.member = 2;
|
->
|
Accesses members of an object with a pointer | objectpointer->member = 2;
|
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