'C' Character set:
The characters in 'C' are grouped in to following categories.
1. Letters - A-Z, a-z
2. Digits - 0-9
3. Special characters.
4. White spaces.
'C' tokens:
Individual words and punctuation names are called tockens.
In a 'C' program the smallest individual units are known as 'C' tockens. They are grouped in to Identifiers, Keywords, Constants, Symbols and Operators.
Identifiers:
Identifiers refer to the names of the variable function and arrays. These are user-defined names.
Rules of Identifiers:
1. Identifiers may contain sequence of letters and digits with a letter as first character, 2. Both uppercase and lower case letters are commonly used but uppercase variable and lower case variable are permitted.
Example:
main
amount
Keywords:
All keywords have fixed meaning and these meaning cannot be changed. Keywords save as a basic building blocks for program statements all the keywords must be written in lower case.
Example:
float
white
Constants:
Constants refer to fixed values that don't change during the execution of a program 'C' supports several types of constants, as shown below.
Constants - Numeric, Character.
Numeric - Integer, Real.
Character - Single character, String.
Integer Constant:
They refer to sequence of digits there are three types of integers.
1. Decimal Constant: It consists of set of digits 0 of through 9. Example: -123, 9.
2. Octal Constant: It consists of set of digits 0 through 7 with leading 0. Example: 037, 0. Rules: May be precedent by on optional + or -.
3. Hexa Decimal Constant: A sequence of digits preceded by ox. They may also include alphabets A through F, 10 represent No. 10 to 15. Example: ox2, ox9F Rules: Embedded spaces, Commas, & non digit characters are not permitted.
Real Constants:
These quantities refer to the nos containing fractional part A real no may also be expressed in exponential notation. Example: 0.00083, -0.75.
Single Character Constant:
A single character constant refer a single character closed with in pair of single quote mark character constant have integer value known as ASCII value. Example: 'S', 'X', 'A'.
Back Slash Character Constant or Escape Sequence:
'C' Supports some special back slash character constants that are used in output functions although they consist of 2 characters the represent one character. These character combinations are know as Escape sequences. For example in represents new line character.
'\a' - alert (bell).
'\b' - Back Space.
'\f' - form feed.
'\n' - New line.
'\r' - Charrage return.
'\t' - Horizontal tab.
'\v' - Vertical tab.
'\'' - Single quote.
'\"' - Double quote.
'\?' - Question mark.
'\0' - Null character.
String Constant:
A string constant is a sequence of characters enclosed in double quotes. Example: "Hello", "Good", "r".
The characters in 'C' are grouped in to following categories.
1. Letters - A-Z, a-z
2. Digits - 0-9
3. Special characters.
4. White spaces.
'C' tokens:
Individual words and punctuation names are called tockens.
In a 'C' program the smallest individual units are known as 'C' tockens. They are grouped in to Identifiers, Keywords, Constants, Symbols and Operators.
Identifiers:
Identifiers refer to the names of the variable function and arrays. These are user-defined names.
Rules of Identifiers:
1. Identifiers may contain sequence of letters and digits with a letter as first character, 2. Both uppercase and lower case letters are commonly used but uppercase variable and lower case variable are permitted.
Example:
main
amount
Keywords:
All keywords have fixed meaning and these meaning cannot be changed. Keywords save as a basic building blocks for program statements all the keywords must be written in lower case.
Example:
float
white
Constants:
Constants refer to fixed values that don't change during the execution of a program 'C' supports several types of constants, as shown below.
Constants - Numeric, Character.
Numeric - Integer, Real.
Character - Single character, String.
Integer Constant:
They refer to sequence of digits there are three types of integers.
1. Decimal Constant: It consists of set of digits 0 of through 9. Example: -123, 9.
2. Octal Constant: It consists of set of digits 0 through 7 with leading 0. Example: 037, 0. Rules: May be precedent by on optional + or -.
3. Hexa Decimal Constant: A sequence of digits preceded by ox. They may also include alphabets A through F, 10 represent No. 10 to 15. Example: ox2, ox9F Rules: Embedded spaces, Commas, & non digit characters are not permitted.
Real Constants:
These quantities refer to the nos containing fractional part A real no may also be expressed in exponential notation. Example: 0.00083, -0.75.
Single Character Constant:
A single character constant refer a single character closed with in pair of single quote mark character constant have integer value known as ASCII value. Example: 'S', 'X', 'A'.
Back Slash Character Constant or Escape Sequence:
'C' Supports some special back slash character constants that are used in output functions although they consist of 2 characters the represent one character. These character combinations are know as Escape sequences. For example in represents new line character.
'\a' - alert (bell).
'\b' - Back Space.
'\f' - form feed.
'\n' - New line.
'\r' - Charrage return.
'\t' - Horizontal tab.
'\v' - Vertical tab.
'\'' - Single quote.
'\"' - Double quote.
'\?' - Question mark.
'\0' - Null character.
String Constant:
A string constant is a sequence of characters enclosed in double quotes. Example: "Hello", "Good", "r".