Character set
A character set is a set of alphabets, letters and some special characters that are valid in C language.
Token
A token is the smallest unit in a 'C' program. A token is divided into six different types as follows,
- Keywords (eg: int, while),
- Identifiers (eg: main, total),
- Constants (eg: 10, 20),
- Strings (eg: “total”, “hello”),
- Special symbols (eg: (), {}),
- Operators (eg: +, /,-,*)
Variables
It is a data name used for storing a data value. Its value may be changed during the program execution. The value of variables keeps on changing during the execution of a program.
Data Types
A data type specifies the type of data that a variable can store such as integer, floating, character, etc.
Keywords
A keyword is a reserved word. You cannot use it as a variable name, constant name, etc. There are only 32 reserved words (keywords) in the C language.
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Auto
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Double
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Int
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Struct
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Break
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Else
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Long
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Switch
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Case
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Enum
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Register
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Typedef
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Char
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Extern
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Return
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Union
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Const
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Float
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Short
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Unsigned
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Continue
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For
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Signed
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Void
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Default
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Goto
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Sizeof
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Volatile
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Do
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If
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Static
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while
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Identifiers
Identifiers are names of variables, functions, and arrays. They are user-defined names, consisting sequence of letters and digits, with the letter as the first character.
Constants
Values do not change during the execution of the program Types:
Numerical constants:
Integer constants
These are the sequence of numbers from 0 to 9 without decimal points or fractional part or any other symbols. It requires minimum two bytes and maximum four bytes.
Eg: 10,20, + 30, – 14
Real constants
It is also known as floating point constants. Eg: 3.5, 6.342
Character constants:
Single character constants
A character constant is a single character. Characters are also represented with a single digit or a single special symbol or white space enclosed within a pair of single quote marks
Eg: ‘a’, ‘6’, “ ”.
String constants
String constants are sequence of characters enclosed within double quote marks. Eg: “Hello”, “goeduhub”, “234”
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