C Programming Floating Point Literals

Floating point literals may be expressed in a variety of formats to simplify the task of expressing different ranges of values.

Rules

• Cannot start with 0 unless the 0 is followed by a decimal point
• Can use e notation to express exponential values (ke±n represents k·10^±n)
• May include a decimal point (should be included when not using e notation)
• Cannot include commas or spaces
• Must use only the digits 0-9
• May be preceded by a minus sign "-"

Examples of Valid Floating Point Literals

The f in the last two examples is a literal qualifier, described on the next page. It forces the compiler to treat as a float, what would otherwise be treated as something else:

• 10 would be treated as an int
• 10.2 would be treated as a double

We'll see why this is important in the section on operators.

Examples of Invalid Floating Point Literals