Floating point constant in C language
Floating point constant
Definition: The numeric values having fractional part are called floating point constants. All negative Numbers should have prefix ‘ ’. A positive number may have a ‘+’ sign that is optional. OtherCharacter are not allowed . The floating point constant can be represented using two forms as:
1. Fractional form
2. Exponent notation(Scientific notation)
Fractional from: Now, let us see ‘‘how to represent floating point numbers using fractional form? Explain giving examples.’’ A floating point number represented using fractional form has an integer part followed by a decimal point and a fractional part. We can omit the digits before the decimal point or after the decimal point. For example, 0.5, 0.99, 6, 9,+.9 etc all are valid floating point numbers.
Exponent notation (Scientific notation): Now , the question is ‘‘How to represent floating point numbers in scientific notation? Give examples.’’ The floating point number represented using Scientific notation (also called exponential notation) has three parts namely:
(part1) (part2) (Part 3)
mantissa e or E exponent
 The mantissa can be an integer or a floating point number represented using fractional Notation.The letter e or should follow mantissa.
 The exponent should follow e or E. The exponent has to be an integer ‘‘with optional ‘+’
 Sign’’ or ‘ ’ sign.
The following table shows invalid floating point numbers. The reasons for invalidity are also shown:
Floating point/ Real Constant

Valid / invalid

Reasons for invalidity

22.0/7

Invalid

/ is not allowed.

120

Invalid

There is no decimal point.

6.5e 8

Invalid

White space is not allowed between e and 8.

1.2.3

Invalid

More than one decimal point is not allowed.

2.123,4

Invalid

Comma is not allowed

10.5e6.9

invalid

Fractional part 6.9 is not allowed in exponent part.

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