Define a C++ language float literal using regular expression. A float literal in C language has an optional exponent part. If a float literal is written without exponent part, then it must have a...

Define a C++ language float literal using regular expression. A float literal in C language has an optional exponent part.

If a float literal is written without exponent part, then it must have a decimal point which can appear at the start, at the end or in the middle of digits, as in following examples:

                        123.456

                        .456

                        456.

If float literal is written with exponent, then decimal point in mantissa part is optional, and exponent is a whole number with optional sign, as in following examples:

            123e78

            123e+78

            123e-78

            123.456e78

            .456e78

            456.e78