Keywords in C
A keyword is a reserved word. We cannot use it as a variable name, constant name, etc. There are only 32 reserved words (keywords) in the C language.
A list of 32 keywords in the C language is given below :
auto | break | case | char |
const | continue | default | do |
double | else | enum | extern |
float | for | goto | if |
int | long | register | return |
short | signed | sizeof | static |
struct | switch | typedef | union |
unsigned | void | volatile | while |
C Operators
An operator is simply a symbol that is used to perform operations. There are the following types of operators to perform different types of operations in C language.
- Arithmetic Operators
- Relational Operators
- Logical Operators
- Bitwise Operators
- Assignment Operator
1. Arithmetic Operators
Operator | Description |
---|---|
+ | Addition |
- | Subtraction |
* | Multiplication |
/ | Division |
% | Modulus |
2. Relational Operators
Operator | Description |
---|---|
== | Is equal to |
!= | Is not equal to |
> | Greater than |
< | Less than |
>= | Greater than or equal to |
<= | Less than or equal to |
3. Logical Operators
Operator | Description | Example |
---|---|---|
&& | Logical AND operator. If both the operands are satisfied, then the condition is true. | (A && B) |
|| | Logical OR operator. If any of two operands is true, then condition becomes true. | (A || B) |
! | Logical NOT operator. It is used to reverse the logical state of its operand. If condition is true, then logical NOT operator will make it false. | !(A && B) or !(A || B) |
4. Bitwise Operators
a | b | a & b | a | b | a ^ b |
---|---|---|---|---|
0 | 0 | 0 | 0 | 0 |
0 | 1 | 0 | 1 | 1 |
1 | 1 | 1 | 1 | 0 |
1 | 0 | 0 | 1 | 1 |
- ~ is the binary one's complement operator.
- << is the binary left shift operator.
- >> is the binary right shift operator.
5. Assignment Operators
Operator | Description |
---|---|
= | Simple assignment operator. Assigns values from right side operands to left side operands. |
+= | Add AND assignment operator. It adds the right operand to the left operand and assign the result to the left operand. |
-= | Subtract AND assignment operator. It subtracts the right operand to the left operand and the result is assigned to the left operand. |
*= | Multiply AND assignment operator. It multiplies the right operand with the left operand and the result is assigned to the left operand. |
/= | Divide AND assignment operator. It divides the left operand with the right operand and the result is assigned to the left operand. |
Precedence and Associativity of Operators in C
The precedence of operator specifies that which operator will be evaluated first and next.
The associativity specifies the operator direction to be evaluated; it may be left to right or right to left.
Category | Operators | Associativity |
---|---|---|
Postfix | () [] {} | Left to Right |
Multiplicative | * / % | Left to Right |
Additive | + - | Left to Right |
Shift | << >> | Left to Right |
Relational | < <= > >= | Left to Right |
Equality | == != | Left to Right |
Bitwise AND | & | Left to Right |
Bitwise XOR | ^ | Left to Right |
Bitwise OR | | | Left to Right |
Logical AND | && | Left to Right |
Logical OR | || | Left to Right |
Assignment | = += -= *= /= %= >>= <<= &= ^= |= | Right to Left |
The + and - are equal in precedence, as *, /, and %.
The *, /, and % are performed first in order from left to right and then + and -, also in order left to right.
We can change the order of operations by using paranthesis () to indicate which operations are to be performed first.
Comments in C
Comments in C language are used to provide information about lines of code. It is widely used for documenting code. There are 2 types of comments in the C language :
- Single Line Comments
- Multi-Line Comments
1. Single Line Comments
Single line comments are represented by double slash // or \\.
#include <stdio.h>
int main()
{
// printing information
printf("Hello C");
return 0;
}
Output :
Hello C
Even we can place the comment after the statement.
printf("Hello C"); // printing information
2. Multiple Line Comments
Multi-Line comments are represented by slash asterisk /* ..... */. It can occupy many line of code, but it can't be nested.
#include <stdio.h>
int main()
{
/* printing information
Multi-Line Comment */
printf("Hello C");
return 0;
}
Output :
Hello C
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