Operators in C
An operator is a symbol that tells the compiler to perform specific mathematical or logical
manipulations. C language is rich in built-in operators and provides the following types of
operators:
Arithmetic operator:
These are used to perform mathematical calculations like addition, subtraction, multiplication, division and modulus.
The following table shows all the arithmetic operators supported by C language. Assume variable A holds 10 and variable B holds 20 then:
| Operator | Description | Example |
|---|---|---|
| + | Adds two operands | A + B will give 30 |
| – | Subtracts the second operand from the first | A – B will give -10 |
| * | Multiplies both operands | A * B will give 200 |
| / | Divides numerator by de-numerator | B / A will give 2 |
| % | Modulus Operator and remainder of after an integerdivision | B % A will give 0 |
| ++ | Increments operator increases integer value by one | A++ will give 11 |
| — | Decrements operator decreases integer value by one | A–-will give 9 |
Relational Operators:
These operators are used to compare the value of two variables.
The following table shows all the relational operators supported by C language. Assume variable A holds 10 and variable B holds 20, then:
| Operator | Description | Example |
|---|---|---|
| == | Checks if the values of two operands are equal or not, if yes then condition becomes true. |
(A == B) is not true. |
| != | Checks if the values of two operands are equal or not, if values are not equal then condition becomes true. | (A != B) is true. |
| > | Checks if the value of left operand is greater than the value of right operand, if yes then condition becomes true. /td> | (A > B) is not true. |
| < | Checks if the value of left operand is less than the value of right operand, if yes then condition becomes true. | (A < B) is true |
| >= | Checks if the value of left operand is greater than or equal to the value of right operand, if yes then condition becomes true. |
(A >= B) is not true. |
| <= | Checks if the value of left operand is less than or equal to the value of right operand, if yes then condition becomes true. | (A <= B) is true. |
Logical Operators:
These operators are used to perform logical operations on the given two variables. Following table shows all the logical operators supported by C language. Assume variable A holds 1 and variable B holds 0, then:
| Operator | Description | Example |
|---|---|---|
| && | Called Logical AND operator. If both the operands are nonzero, then condition becomes true. | (A && B) is false. |
| || | Called Logical OR Operator. If any of the two operands is non-zero, then condition becomes true. | (A || B) is true. |
| ! | Called Logical NOT Operator. Use to reverses the logical state of its operand. If a condition is true then Logical NOToperator will make false. | !(A && B) is true. |
Bitwise Operators
Bitwise operator works on bits and performs bit-by-bit operation. Bitwise operators are used in bit level programming. These operators can operate upon int and char but not on float and double.
Showbits( ) function can be used to display the binary representation of any integer or character value.
Bit wise operators in C language are; & (bitwise AND), | (bitwise OR), ~ (bitwise OR), ^ (XOR), << (left shift) and >> (right shift).
The truth tables for &, |, and ^ are as follows:
| P | Q | p & q | p | q | p ^ q |
|---|---|---|---|---|
| 0 | 0 | 0 | 0 | 0 |
| 0 | 1 | 0 | 1 | 1 |
| 1 | 1 | 1 | 1 | 0 |
| 1 | 0 | 0 | 1 | 1 |
The Bitwise operators supported by C language are explained in the following table. Assume variable A holds 60 (00111100) and variable B holds 13 (00001101), then:
| Operator | Description | Example |
|---|---|---|
| & | Binary AND Operator copies a bit to the result if it exists in both operands. | (A & B) will give 12, which is 0000 1100 |
| | | Binary OR Operator copies a bit if it exists in either operand. | (A | B) will give 61,which is 0011 1101 |
| ^ | Binary XOR Operator copies the bit if it is set in one operand but not both. | (A ^ B) will give 49, which is 0011 0001 |
| ~ | Binary Ones Complement Operator is unary and has the effect of ‘flipping’ bits. | (~A ) will give -61, which is 1100 0011 in 2’s complement form. |
| << | Binary Left Shift Operator. The left operands value is moved left by the number of bits specified by the right operand. | A << 2 will give 240 which is 1111 0000 |
| >> | Binary Right Shift Operator. The left operands value is moved right by the number of bits specified by the right operand. | A >> 2 will give 15 which is 0000 1111 |
Assignment Operators
In C programs, values for the variables are assigned using assignment operators.
There are the following assignment operators supported by C language:
| Operator | Description | Example |
|---|---|---|
| = | Simple assignment operator, Assigns values from right side operands to left side operand | C = A + B will assign value of A + B into C |
| += | Add AND assignment operator, It adds right operand to the left operand and assign the result to left operand | C += A is equivalent to C = C + A |
| -= | Subtract AND assignment operator, It subtracts right operand from the left operand and assign the result to the left operand | C -= A is equivalent to C = C– A |
| *= | Multiply AND assignment operator, It multiplies right operand with the left operand and assign the result to left operand | C *= A is equivalent to C = C* A |
| /= | Divide AND assignment operator, It divides left operand with the right operand and assign the result to left operand | C /= A is equivalent to C = C/ A |
| %= | Modulus AND assignment operator, It takes modulus using two operands and assign the result to left operand | C %= A is equivalent to C = C% A |
| <<= | Left shift AND assignment operator | C <<= 2 is same as C = C << 2 |
| >>= | Right shift AND assignment operator | C >>= 2 is same as C = C >> 2 |
| &= | Bitwise AND assignment operator | C &= 2 is same as C = C & 2 |
| ^= | bitwise exclusive OR and assignment operator | C ^= 2 is same as C = C ^ 2 |
| |= | bitwise inclusive OR and assignment operator | C |= 2 is same as C = C | 2 |
Increment And Decrement Operator
In C, ++ and – are called increment and decrement operators respectively. Both of these operators are unary operators, i.e, used on single operand. ++ adds 1 to operand and – subtracts 1 to operand respectively. For example:
Let a=5 and b=10 a++; //a becomes 6 a--; //a becomes 5 ++a; //a becomes 6 --a; //a becomes 5
When i++ is used as prefix(like: ++var), ++var will increment the value of var and then return it but, if ++ is used as postfix(like: var++), operator will return the value of operand first and then only increment it. This can be demonstrated by an example:
#includeint main() { int c=2,d=2; printf(“%d\n”,c++); //this statement displays 2 then, only c incremented by 1 to 3. Printf(“%d”,++c); //this statement increments 1 to c then, only c is displayed. Return 0; } Output 2 4
Conditional Operators (?:)
Conditional operators are used in decision making in C programming, i.e, executes different statements according to test condition whether it is either true or false.
Syntax of conditional operators;
conditional_expression?expression1:expression2
If the test condition is true (that is, if its value is non-zero), expression1 is returned and if false
expression2 is returned.
Let us understand this with the help of a few examples:
int x, y ; scanf ( “%d”, &x ) ; y = ( x> 5 ? 3 : 4 ) ; This statement will store 3 in y if x is greater than 5, otherwise it will store 4 in y. The equivalent if statement will be, if ( x > 5 ) y = 3 ; else y = 4 ;
Misc Operators:
There are few other operators supported by c language.
| Operator | Description | Example |
|---|---|---|
| sizeof() | It is a unary operator which is used in finding the size of data type, constant, arrays, structure etc | sizeof(a), where a is integer, will return 4 |
| & | Returns the address of a variable | &a; will give actual address of the variable. |
| * | Pointer to a variable | *a; will pointer to a variable. |