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.