Updated April 6, 2023
Introduction to Unary Operator in C
Unary Operator in C is used to produce a new value by acting upon a single operand. All unary operators are having equal precedence from right side to left side associativity. Unary minus(-), unary plus(+), prefix increment(++a) and decrement(–a), postfix increment(a++) and decrement(a–), Logical negation(!), address operator(&), indirection operator(*), cast operator and sizeof() operator comes under “Unary operator”.
Types of Unary Operators
Given below are the types of unary operators:
1. Unary minus(-)
2. Unary plus(+)
3. Increment(++)
- Pre increment(++variable)
- Post increment(variable++)
4. Decrement(–)
- Pre decrement(–variable)
- Post decrement(variable–)
5. Logical Negation(!)
6. Address Operator(&)
7. sizeof() Operator
How does Unary Operators work in C?
Unary Operator in C works based on which type of operator we are applied on a variable, according to that it will perform its corresponding operation.
1. Unary minus(-)
Unary minus changes the sign of the any argument. It will change positive number becomes negative and negative number becomes positive.
Syntax:
int variable1= value;
int variable2= -value //value becomes negativeCode:
//used to include basice c library files
#include <stdio.h>
//main method for run the C application
intmain()
{
//declaring variables
int a, unaryMinus;
//Asking user to enter any number
printf("Please enter any number \n");
//store the enter number in the int variable
scanf("%d",&a);
//unary minus operation performed, negative number becomes positive and positive number becomes negative
unaryMinus=-(a);
//displaying output
printf("Unary minus operation of %d is = %d ",a, unaryMinus);
return 0;
}Output:
2. Unary plus(+)
Unary plus changes the sign of the any negative argument. It will change negative number becomes positive and positive number becomes positive.
Syntax:
int variable1= -value;
int variable2= +value //negative value becomes positiveCode:
//used to include basice c library files
#include <stdio.h>
//main method for run the C application
intmain()
{
//declaring variables
int a, unaryPlus;
//Asking user to enter any number
printf("Please enter any number \n");
//store the enter number in the int variable
scanf("%d",&a);
//unary plus operation performed, negative number becomes positive and positive number becomes positive only
unaryPlus=+(a);
//displaying output
printf("Unary plus operation of %d is =%d ",a, unaryPlus);
return 0;
}Output:
3. Increment(++)
a. Pre increment(++variable)
It will increment variable value by 1 before assigning the value to the variable.
Syntax:
intvar=11;
int out=++var; //out becomes 12Code:
//used to include basice c library files
#include <stdio.h>
//main method for run the C application
intmain()
{
//declaring variables
int a, pre_increment;
//Asking user to enter any number
printf("Please enter any number \n");
//store the enter number in the int variable
scanf("%d",&a);
//take temp variable for showing actual number in output
int temp=a;
//increment value by 1 before assigning the value
pre_increment=++a;
//displaying output
printf("Pre increment operation of %d is =%d ",temp, pre_increment);
return 0;
}Output:
b. Post increment(variable++)
It will increment variable value by 1 after assigning the value to the variable.
Syntax:
intvar=11;
int out=var++; //out becomes 11Code:
//used to include basice c library files
#include <stdio.h>
//main method for run the C application
intmain()
{
//declaring variables
int a, post_increment;
//Asking user to enter any number
printf("Please enter any number \n");
//store the enter number in the int variable
scanf("%d",&a);
//take temp variable for showing actual number in output
int temp=a;
//increment value by 1 after assigning the value
post_increment=a++;
//displaying output
printf("Post increment operation of %d is =%d ",temp, post_increment);
return 0;
}Output:
4. Decrement(–)
a. Pre decrement(–variable)
It will decrement variable value by 1 before assigning the value to the variable.
Syntax:
intvar=11;
int out=--var; //out becomes 10Code:
//used to include basice c library files
#include <stdio.h>
//main method for run the C application
intmain()
{
//declaring variables
int a, pre_decrement;
//Asking user to enter any number
printf("Please enter any number \n");
//store the enter number in the int variable
scanf("%d",&a);
//take temp variable for showing actual number in output
int temp=a;
//decrement value by 1 before assigning the value
pre_decrement=--a;
//displaying output
printf("Pre decrement operation of %d is =%d ",temp, pre_decrement);
return 0;
}Output:
b. Post decrement(variable–)
It will decrement variable value by 1 after assigning the value to the variable.
Syntax:
intvar=11;
int out=var--; //out becomes 11Code:
//used to include basice c library files
#include <stdio.h>
//main method for run the C application
intmain()
{
//declaring variables
int a, post_decrement;
//Asking user to enter any number
printf("Please enter any number \n");
//store the enter number in the int variable
scanf("%d",&a);
//take temp variable for showing actual number in output
int temp=a;
//decrement value by 1 before assigning the value
post_decrement=a--;
//displaying output
printf("Post decrement operation of %d is =%d ",temp, post_decrement);
return 0;
}Output:
5. Logical Negation(!)
It is used to reverse the logical state of its operand like true become false and false becomes true vice versa.
Syntax:
bool b=false;
bool out=!b //beocmes out is trueCode:
//used to include basice c library files
#include <stdio.h>
#include <stdbool.h>
//main method for run the C application
intmain()
{
//declaring variables
bool a=false, negation;
//take temp variable for showing actual number in output
bool temp=a;
//negation operator
negation=!a;
//displaying output
//In C o means false and 1 means true
printf("Negation of %d is =%d ",temp, negation);
return 0;
}Output:
6. Address Operator(&)
It will give the address of the variable. It is used to return the memory address of the any variable. This is also called as pointers in C.
Syntax:
int a=10;
int out=&a // Based on compiler value may variesCode:
//used to include basice c library files
#include <stdio.h>
//main method for run the C application
intmain()
{
//declaring variables
int a=12, address;
//take temp variable for showing actual number in output
int temp=a;
//address operator assigning to the variable
address=&a;
//displaying output
printf("Address of %d is =%d ",temp, address);
return 0;
}Output:
7. sizeof() Operator
It will return the size of the variable in bytes. It always precedes its operand.
Syntax:
int a=10;
int out=sizeof(a); //return the int size as 2 or 4 based on platformCode:
//used to include basice c library files
#include <stdio.h>
//main method for run the C application
intmain()
{
//declaring variables
int a=12, sizeof_value;
//sizeof operator assigning to the variable
sizeof_value=sizeof(a);
//displaying output
//it is inter so size either 2 or 4
printf("size of of %d is =%d ",a, sizeof_value);
return 0;
}Output:
Conclusion
Unary Operator in C is used to apply on single variable or operand. Unary minus, pre increment and decrement, post increment and decrement, negation, address and sizeof() operators are unary operators in C.
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