An operator is a symbol that operates on a value or a variable. For example: `+` is an operator to perform addition.

C has a wide range of operators to perform various operations.

## C Arithmetic Operators

An arithmetic operator performs mathematical operations such as addition, subtraction, multiplication, division etc on numerical values (constants and variables).

Operator | Meaning of Operator |
---|---|

+ | addition or unary plus |

- | subtraction or unary minus |

* | multiplication |

/ | division |

% | remainder after division (modulo division) |

### Example 1: Arithmetic Operators

```
// Working of arithmetic operators
#include <stdio.h>
int main()
{
int a = 9,b = 4, c;
c = a+b;
printf("a+b = %d \n",c);
c = a-b;
printf("a-b = %d \n",c);
c = a*b;
printf("a*b = %d \n",c);
c = a/b;
printf("a/b = %d \n",c);
c = a%b;
printf("Remainder when a divided by b = %d \n",c);
return 0;
}
```

**Output**

a+b = 13 a-b = 5 a*b = 36 a/b = 2 Remainder when a divided by b=1

The operators `+`

, `-`

and `*`

computes addition, subtraction, and multiplication respectively as you might have expected.

In normal calculation, `9/4 = 2.25`

. However, the output is `2`

in the program.

It is because both the variables `a` and b are integers. Hence, the output is also an integer. The compiler neglects the term after the decimal point and shows answer `2`

instead of `2.25`

.

The modulo operator `%`

computes the remainder. When `a=9`

is divided by `b=4`

, the remainder is `1`

. The `%`

operator can only be used with integers.

Suppose `a = 5.0`

, `b = 2.0`

, `c = 5`

and `d = 2`

. Then in C programming,

// Either one of the operands is a floating-point number a/b = 2.5 a/d = 2.5 c/b = 2.5 // Both operands are integers c/d = 2

## C Increment and Decrement Operators

C programming has two operators increment `++`

and decrement `--`

to change the value of an operand (constant or variable) by 1.

Increment `++`

increases the value by 1 whereas decrement `--`

decreases the value by 1. These two operators are unary operators, meaning they only operate on a single operand.

### Example 2: Increment and Decrement Operators

```
// Working of increment and decrement operators
#include <stdio.h>
int main()
{
int a = 10, b = 100;
float c = 10.5, d = 100.5;
printf("++a = %d \n", ++a);
printf("--b = %d \n", --b);
printf("++c = %f \n", ++c);
printf("--d = %f \n", --d);
return 0;
}
```

**Output**

++a = 11 --b = 99 ++c = 11.500000 --d = 99.500000

Here, the operators `++`

and `--`

are used as prefixes. These two operators can also be used as postfixes like `a++`

and `a--`

. Visit this page to learn more about how increment and decrement operators work when used as postfix.

## C Assignment Operators

An assignment operator is used for assigning a value to a variable. The most common assignment operator is `=`

Operator | Example | Same as |
---|---|---|

= | a = b | a = b |

+= | a += b | a = a+b |

-= | a -= b | a = a-b |

*= | a *= b | a = a*b |

/= | a /= b | a = a/b |

%= | a %= b | a = a%b |

### Example 3: Assignment Operators

```
// Working of assignment operators
#include <stdio.h>
int main()
{
int a = 5, c;
c = a; // c is 5
printf("c = %d\n", c);
c += a; // c is 10
printf("c = %d\n", c);
c -= a; // c is 5
printf("c = %d\n", c);
c *= a; // c is 25
printf("c = %d\n", c);
c /= a; // c is 5
printf("c = %d\n", c);
c %= a; // c = 0
printf("c = %d\n", c);
return 0;
}
```

**Output**

c = 5 c = 10 c = 5 c = 25 c = 5 c = 0

### C Relational Operators

A relational operator checks the relationship between two operands. If the relation is true, it returns 1; if the relation is false, it returns value 0.

Relational operators are used in decision making and loops.

Operator | Meaning of Operator | Example |
---|---|---|

== | Equal to | `5 == 3` is evaluated to 0 |

> | Greater than | `5 > 3` is evaluated to 1 |

< | Less than | `5 < 3` is evaluated to 0 |

!= | Not equal to | `5 != 3` is evaluated to 1 |

>= | Greater than or equal to | `5 >= 3` is evaluated to 1 |

<= | Less than or equal to | `5 <= 3` is evaluated to 0 |

### Example 4: Relational Operators

```
// Working of relational operators
#include <stdio.h>
int main()
{
int a = 5, b = 5, c = 10;
printf("%d == %d is %d \n", a, b, a == b);
printf("%d == %d is %d \n", a, c, a == c);
printf("%d > %d is %d \n", a, b, a > b);
printf("%d > %d is %d \n", a, c, a > c);
printf("%d < %d is %d \n", a, b, a < b);
printf("%d < %d is %d \n", a, c, a < c);
printf("%d != %d is %d \n", a, b, a != b);
printf("%d != %d is %d \n", a, c, a != c);
printf("%d >= %d is %d \n", a, b, a >= b);
printf("%d >= %d is %d \n", a, c, a >= c);
printf("%d <= %d is %d \n", a, b, a <= b);
printf("%d <= %d is %d \n", a, c, a <= c);
return 0;
}
```

**Output**

5 == 5 is 1 5 == 10 is 0 5 > 5 is 0 5 > 10 is 0 5 < 5 is 0 5 < 10 is 1 5 != 5 is 0 5 != 10 is 1 5 >= 5 is 1 5 >= 10 is 0 5 <= 5 is 1 5 <= 10 is 1

### C Logical Operators

An expression containing logical operator returns either 0 or 1 depending upon whether expression results true or false. Logical operators are commonly used in decision making in C programming.

Operator | Meaning | Example |
---|---|---|

&& | Logical AND. True only if all operands are true | If c = 5 and d = 2 then, expression `((c==5) && (d>5))` equals to 0. |

|| | Logical OR. True only if either one operand is true | If c = 5 and d = 2 then, expression `((c==5) || (d>5))` equals to 1. |

! | Logical NOT. True only if the operand is 0 | If c = 5 then, expression `!(c==5)` equals to 0. |

### Example 5: Logical Operators

```
// Working of logical operators
#include <stdio.h>
int main()
{
int a = 5, b = 5, c = 10, result;
result = (a == b) && (c > b);
printf("(a == b) && (c > b) is %d \n", result);
result = (a == b) && (c < b);
printf("(a == b) && (c < b) is %d \n", result);
result = (a == b) || (c < b);
printf("(a == b) || (c < b) is %d \n", result);
result = (a != b) || (c < b);
printf("(a != b) || (c < b) is %d \n", result);
result = !(a != b);
printf("!(a != b) is %d \n", result);
result = !(a == b);
printf("!(a == b) is %d \n", result);
return 0;
}
```

**Output**

(a == b) && (c > b) is 1 (a == b) && (c < b) is 0 (a == b) || (c < b) is 1 (a != b) || (c < b) is 0 !(a != b) is 1 !(a == b) is 0

**Explanation of logical operator program**

`(a == b) && (c > 5)`

evaluates to 1 because both operands`(a == b)`

and`(c > b)`

is 1 (true).`(a == b) && (c < b)`

evaluates to 0 because operand`(c < b)`

is 0 (false).`(a == b) || (c < b)`

evaluates to 1 because`(a = b)`

is 1 (true).`(a != b) || (c < b)`

evaluates to 0 because both operand`(a != b)`

and`(c < b)`

are 0 (false).`!(a != b)`

evaluates to 1 because operand`(a != b)`

is 0 (false). Hence, !(a != b) is 1 (true).`!(a == b)`

evaluates to 0 because`(a == b)`

is 1 (true). Hence,`!(a == b)`

is 0 (false).

### C Bitwise Operators

During computation, mathematical operations like: addition, subtraction, multiplication, division, etc are converted to bit-level which makes processing faster and saves power.

Bitwise operators are used in C programming to perform bit-level operations.

Operators | Meaning of operators |
---|---|

& | Bitwise AND |

| | Bitwise OR |

^ | Bitwise exclusive OR |

~ | Bitwise complement |

<< | Shift left |

>> | Shift right |

Visit bitwise operator in C to learn more.

## Other Operators

### Comma Operator

Comma operators are used to link related expressions together. For example:

`int a, c = 5, d;`

### The sizeof operator

The `sizeof`

is a unary operator that returns the size of data (constants, variables, array, structure, etc).

### Example 6: sizeof Operator

```
#include <stdio.h>
int main()
{
int a;
float b;
double c;
char d;
printf("Size of int=%lu bytes\n",sizeof(a));
printf("Size of float=%lu bytes\n",sizeof(b));
printf("Size of double=%lu bytes\n",sizeof(c));
printf("Size of char=%lu byte\n",sizeof(d));
return 0;
}
```

**Output**

Size of int = 4 bytes Size of float = 4 bytes Size of double = 8 bytes Size of char = 1 byte

Other operators such as ternary operator `?:`

, reference operator `&`

, dereference operator `*`

and member selection operator `->`

will be discussed in later tutorials.