Operators in C Programming

Operators in C

Operators:

  • Operators are used in programs to manipulate data and variables.
  • If an operator acts on a single variable, then it is called ‘Unary Operator’.
  • If an operator acts on two variables then it is called ‘Binary operator’.
  • If an operator acts on three variables then it is called ‘Ternary operator’.

The below table specifies list of Operators available in C

Operator Category Operator Symbols
Arithmetic Operators +,-,*,/,%
Assignment Operators =,+=,-=,*=,/=,%=
Unary Operators -,++ and —

Arithmetic Operators:

  • These operators are useful to perform basic arithmetic operations.
Operator Meaning
+ Addition
Subtraction
* Multiplication
/ Division
% Modulus Operator

Assignment Operators:

  • The purpose of the assignment operator is to assign or store a value into a variable.
int x=15; /* the value 15 is stored into x */
int x=y; /* Store y value into x */
  • from the above examples, we can understand that always the right-hand side value is stored into the left side variable. So, we cannot write something like this.
15=x; /*invalid, since variable is not present at left side */
  • Using the assignment operator (=), we can write expressions in a compact form also.
sal=sal+500 can be written as sal+=500
num=num-100 can be written as num-=100
p=p/100 can be written as p/=100

Unary Operators:

  • Unary minus operator (-): This operator is useful to negate a value. Negation means converting a positive value into negative value and vice versa.
int x=7; 
x=-x; /* negate the value of x and store into x */
  • Since x value is 7,-x will be -7. This will be stored into the left side variable x so, after execution, x value will become -5.
  • Increment Operator (++): This operator is useful to increase the value of a variable by 1.
int n=5 /*value of n is 5 */
++n; /*now n value becomes 6 */
  • we can write ++ symbol either before or after the variable.
n++; /* in this case also, n value will be incremented by 1 */
  • writing ++ before a variable is called ‘pre-increment’ and writing ++ after a variable is called ‘post-increment’. Both will increase the value of the variable. But there is a difference in the timing of the increment.
  • In pre incrementation, the value of the variable is incremented first, any other operation is done next. In post incrementation, all operations are done first.

Decrement Operator (–): This operator decreases the value of a variable by 1.

int n=8; /* value of n is 8 */
--n; /* now n value becomes 4 */
  • we can write — symbol either before or after the variable.
n--; /* in this case also, n value will be decremented by 1 */
  • writing — before a variable is called ‘pre decrementation‘ and writing — after a variable is called ‘post decrementation‘. Both will decrease the value of the variable by 1. But there is a difference in the timing of the increment.
  • In pre decrementation, the value of the variable is decremented first, any other operation is done next. In post decrementation, all operations are done first and the demonstration is done at the end.

Ternary Operator( ?: )

  • This operator is called ‘Ternary operator’ because it acts on 3 expressions. It is also called as ‘Conditional Operator’.
General Syntax: variable=expression1 ? expression2: expression3;
  • if expression1 is true, then the value of expression2 will be evaluated and stored into the variable. If expression1 is false, then the value of expression3 will be stored into the variable.
if(expression)
variable=expression2;
else variable=expression3;
  • The preceding statement is called ‘Conditional statement’, because it performs a task depending on whether the condition is true or false.
 max=(num1 > num2) ? num1 : num2;
  • In the below example, if num1 is really greater than num2, then num1 value is stored into max, otherwise, num2 value is stored into max. The same expression can be rewritten in C as:
if(num1>num2)
max=num1;
else max=num2;

Relational Operators

  • These Operators are useful to compare two quantities, to know whether a quantity is bigger or smaller than another one or not.
Operator Meaning
< 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

Table: Relational Operators 

Logical Operators

  • Logical operators are used to joining two or more conditions when we join two or more simple conditions, it becomes a compound condition.
Operator Meaning
&& Logical AND
|| Logical OR
! Logical NOT

Table: Logical Operators 

if(a == 1 && b == 2) printf("%d\t%d",a,b);
  • Here, && is used to combine two conditions; a == 1 and b == 2.This means, a value should be 1 and also b value should be 2. Then only, the next printf() statement will be executed.

Bitwise Operators

  • Bitwise complement operator (~): This operator returns the complement form of a number system. Converting 0s into 1s and vice versa is called complement.
int x=10;
~x=?
  • first, convert 10 into the binary number system. we get 0000 1010. To get the complement for this number, we convert 0s into 1s and vice versa. Thus we get 1111 0101. This is equal to -11 in the decimal number system. So, ~x gives us the result -11.

Bitwise AND operator (&): This operator performs ANDing operation on bits. When two bits are ANDed, the result is shown in the below table.

x y x & y
0 0 0
0 1 0
1 0 0
1 1 1

 

  • Let us find the result of bitwise AND operation of two numbers 10 and 12.
x = 10 =0000 1010
y = 12 =0000 1100
-------------------------
x & y = 0000 1000 = 8 in decimal

Bitwise OR operator ( | ): This operator performs ORing operation on bits. When two bits are ORed, the result is shown in the below table.

x y x | y
0 0 0
0 1 1
1 0 1
1 1 1

 

  • Let us find the result of the bitwise OR operation of two numbers 10 and 12.
x = 10 =0000 1010
y = 12 =0000 1100
-------------------------
x & y =0000 1110 = 14 in decimal

Bitwise XOR operator ( ^ ): This operator performs XORing operation on bits. Here, XOR represents exclusive OR operation. The symbol ‘^’ is called ‘cap’ or ‘caret’.When two bits are XORed, the result is shown in the below table.

x y x ^ y
0 0 1
0 1 0
1 0 0
1 1 1

 

  • Let us find the result of the bitwise XOR operation of two numbers 10 and 12.
x = 10 =0000 1010
y = 12 =0000 1100
-------------------------
x & y = 0000 0110 = 6 in decimal

sizeof() Operator:

  • This operator returns the size of a variable.
int num;
sizeof(num) returns 4 since the int type variable takes 4 byte of memory.

 

  • sizeof() can also be used with datatypes to know the size of a datatype.

& Operator

  • It is used for allotting memory for the variable.
int x; /*allots 4 Bytes of memory for x */

 

  • The memory address of the variable can be known using & operator. it is also called the ‘address of’ operator.
&x; /*memory address of x */

* Operator:

  • It is useful to declare a pointer. A pointer is a variable that stores a memory address. If x is a variable, its memory address can be represented by &x.
int *x; /* p is a pointer of int type */
p=x; /*store memory address of x into p */

 

  • Now p has the memory address, we can also find the value of x through p. *p represents the value of x.
    The pointer operator is used in 2 ways: to declare a pointer and to find the value of the variable which is pointed.

 

operator precedence in C

naveed08st
 

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