Identifier and its types, Structure of data type and its memory size in C language, 

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Identifier and its types

Identifier: -

An identifier is the name that presents a variable, constant, data types, function, or label in a program. In the C language, an identifier consists of a combination of alphanumeric characters, such that:

• The first is always a letter of the alphabet or an (_) underscore.

• The remaining can be any letter, numeric digit, or the underscore.

There are two types of identifier in C language.

(1) Standard identifier (2) User-define identifier

(1) Standard identifier: -

The names of defined operations in C language are called identifier. For example, scanf and printf represent input and output functions. These are the standard identifiers.

(2) User- defined identifier: -

These are the names that a programmer assigns to function, data type, variable, etc. in a program.

Structure of data type and its memory size in C language

• Data type Format specifier Data range                     Memory occupied
• Int                 % d                   -32768-> +32767                       2 bytes
• Long             % ld                  -2147483648-> +2147483647   4 bytes
• Float             % f                    3.4*10-38-> 304*10+38            4 bytes
• Double          % lf                  107*10-108-> 1.7*10+108         8 bytes
• Char              % C                   -128->- +127                             1 bytes