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C Operators

Operators

Operators are used to perform operations on variables and values.

In the example below, we use the + operator to add together two values:

Example

int myNum = 100 + 50;

Although the + operator is often used to add together two values, like in the example above, it can also be used to add together a variable and a value, or a variable and another variable:

Example

int sum1 = 100 + 50;        // 150 (100 + 50)
int sum2 = sum1 + 250;      // 400 (150 + 250)
int sum3 = sum2 + sum2;     // 800 (400 + 400)

C divides the operators into the following groups:

  • Arithmetic operators
  • Assignment operators
  • Comparison operators
  • Logical operators
  • Bitwise operators

Arithmetic Operators

Arithmetic operators are used to perform common mathematical operations.

Operator Name Description Example Try it
+ Addition Adds together two values x + y
- Subtraction Subtracts one value from another x - y
* Multiplication Multiplies two values x * y
/ Division Divides one value by another x / y
% Modulus Returns the division remainder x % y
++ Increment Increases the value of a variable by 1 ++x
-- Decrement Decreases the value of a variable by 1 --x

Assignment Operators

Assignment operators are used to assign values to variables.

In the example below, we use the assignment operator (=) to assign the value 10 to a variable called x:

Example

int x = 10;

The addition assignment operator (+=) adds a value to a variable:

Example

int x = 10;
x += 5;

A list of all assignment operators:

Operator Example Same As Try it
= x = 5 x = 5
+= x += 3 x = x + 3
-= x -= 3 x = x - 3
*= x *= 3 x = x * 3
/= x /= 3 x = x / 3
%= x %= 3 x = x % 3
&= x &= 3 x = x & 3
|= x |= 3 x = x | 3
^= x ^= 3 x = x ^ 3
>>= x >>= 3 x = x >> 3
<<= x <<= 3 x = x << 3

Comparison Operators

Comparison operators are used to compare two values (or variables). This is important in programming, because it helps us to find answers and make decisions.

The return value of a comparison is either 1 or 0, which means true (1) or false (0). These values are known as Boolean values, and you will learn more about them in the and chapter.

In the following example, we use the greater than operator (>) to find out if 5 is greater than 3:

Example

int x = 5;
int y = 3;
printf("%d", x > y); // returns 1 (true) because 5 is greater than 3

A list of all comparison operators:

Operator Name Example Try it
== Equal to x == y
!= Not equal x != y
> Greater than x > y
< Less than x < y
>= Greater than or equal to x >= y
<= Less than or equal to x <= y

Logical Operators

You can also test for true or false values with logical operators.

Logical operators are used to determine the logic between variables or values:

Operator Name Description Example Try it
&&  Logical and Returns true if both statements are true x < 5 &&  x < 10
||  Logical or Returns true if one of the statements is true x < 5 || x < 4
! Logical not Reverse the result, returns false if the result is true !(x < 5 && x < 10)

Sizeof Operator

The memory size (in bytes) of a data type or a variable can be found with the sizeof operator:

Example

int myInt;
float myFloat;
double myDouble;
char myChar;

printf("%lun", sizeof(myInt));
printf("%lun", sizeof(myFloat));
printf("%lun", sizeof(myDouble));
printf("%lun", sizeof(myChar));

Note that we use the %lu format specifer to print the result, instead of %d. It is because the compiler expects the sizeof operator to return a long unsigned int (%lu), instead of int (%d). On some computers it might work with %d, but it is safer to use %lu.

C Operators
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