Rules for Constructing Real Constants

Real constants are often called Floating Point constants. The real constants could be written in two forms.

1. Fractional form
2. Exponential form.

Fractional form:

• A real constant must have at least one digit.
• It must have a decimal point.
• It could be either positive or negative.
• Default sign is positive.
• No commas or blanks are allowed within a real constant.

Ex:
      +235.33
        516.0
       -34.73
       -36.5789

Exponential form:

• The mantissa part and the exponential part should be separated by a letter e.
• The mantissa part may have a positive or negative sign.
• Default sign of mantissa part is positive.
• The exponent must have at least one digit, which must be a positive or negative integer. Default sign is positive.
• Range of real constants expressed in exponential form is -3.4e38 to 3.4e38.

Ex:
       +2.3e-5
         5.1e5
       -0.2e+4
       -3.5e-4