Getting started with C Language

Operator

An operator is a symbol in a program which instruct the computer to do many mathematical and logical manipulations. They are used in C language program to operate on data and variables. In C there are a rich set of operators.

Types of operators

• Arithmetic operators
• Relational operators
• Logical operators
• Assignment operators
• Increment and Decrement operators
• Conditional operators
• Bitwise operators
• Special operators

Arithmetic operators

These are the operators which are used for arithmetic  and unary +or -purposes. The operators are +,-,*,/,%. In c language the results from the expressions on right side is stored in to the variable in left hand side.  

Consider A=5 and B=2 then the results of the operations stored in C will be

Relational operator

Relational operator is used to compare two quantifiers depending up on their relation. Relational operators are used for decision making. Any comparisons in program is done with these relational operators. An expression containing a relational operator is called relational expression.

A relational operator returns a true or false value. The syntax of relational operations is

Arithmetic expression1 relational operator  Arithmetic expression2

The arithmetic expression may be constants variables or combination of them. When using  arithmetic operations in relational operations first evaluate the arithmetic expressions and the results are compared. Relational operators are used in decision making statements like if, while, etc

When A=10 and B=5 then

We can also write relational expressions like

A+B>C+D, a==0, c!=100,….

Logical operators

There are 3 logical operators in C language . AND , OR and NOT. Logical operators are used in decision making which we want to test more than one condition. A logical expression valuates and returns the values 0 and 1. We use logical statements with decision making statements.

The following table illustrate how the logical operator works whwn the value of A=1, B=5

Assignment operator

Assignment operator is used to assign the values or value of expressions on right hand side to the variable in left side.  The ‘=’ sign is used for the assignment.

V=expression;

Where expression may be  a variable , a value , or any expression or arithmetic operation.

Example :

Thus the value in the right is assigned to the variable in left.

 Short hand assignment operator

A+=1; which is a shorthand statement for  A=A+1

A-=1; which is a shorthand statement for  A=A-1

If A=1,B=2  then

C=A+B;

 returns c=3                                   

Increment and Decrement operators

These are one of the useful operator in C language, also found in other languages.++ and  -- are used to denote increment and decrement operators.The operator ++ adds 1 to the operand while  - - subtracts 1

A++ is equalent to A=A+1

A-- is similar to A=A-1

Also we can write increment and decrement operators like

++A;

--A;

We mainly use these statements while using the loops.

Conditional operators

It’s a ternary operator used for decision making using expressions.

Syntax :

expression1?expression2:expression3;

which means evaluates expression1 and if it is true then perform the expression2 and skip the expression3. And if the expression1 is false then skip the expression2 and performs expression3.

example:

consider if A=5,B=10 then

A>B?C=A:C=B;

here evaluates A>B which is checks 5>10 which is false, thus performs the third expression C=B that is assigning the value of B into  C and skips the expression C=A, if the condition were true then the value of  A would be assigned to C. Thus C returns the greatest value.

We can replace the conditional operator with an ‘if’ statement .

Bitwise operator

Bitwise operators are used for manipulating data at its bit level these are used for testing the bits or shifting them in to left or right. It can’t used for float and double data types.

Special operators

C supports some special operators such as COMMA operator, SIZEOF operator, POINTER operators(like ‘&’and’*’) and member selection operators (‘.’and ‘->’).

Comma operator:

Comma operator is used to separate expressions while the expressions are evaluated from left to right.

Example :

Value=(x=10,y=5,x+y) here first assigns the value 10 in to x then 5 to y and then the result of x+y (10+5) in to the Variable value.

Sizeof operator:

Sizeof operator is a compile time operator used with an operand, which returns the number of bytes the operand occupies.

Syntax:

sizeof(expression);

the expression can be a variable or a data type.

Example:

A=sizeof(B);

A=sizeof(double);

Pointer operators

We use pointer operators ‘&’and ’*’ along with pointers. By using ‘&’ we gets the address or location of the variable.

P=&Q then the value of P will be the address of the variable Q.

The '*' operator is used to initialize the pointer data types.

Datatype  *pointer-name;

Example :

int *P; which means P is a pointer variable that points to a integer data type.

Member function operator

The member function operators like ‘ . ‘and ’ ->’ are used to access the data members of structure union and linked lists.