Question

Write a regular expression that matches:

a) all strings that end with a dot character ".", without the quotes.

b) all strings that begin with a "#" character, without the quotes.

c) all floating-point numbers using standard notation (e.g., 12.345 or –12.345). Note that matching numbers may contain any number of digits before or after the decimal point.

d) all floating-point numbers using scientific notation (e.g., 1.234e+5 or –1.234E–5). Again, matching numbers may contain any number of digits before or after the decimal point.

Answer 1

a) pattern = ^[a-zA-Z0-9]+\.$

b) pattern = ^#[a-zA-Z0-9]+$

c) pattern = [+-]?([0-9]*[.])?[0-9]+

d) pattern = [+-]?([0-9eE]*[.])?[0-9]+[+-]?[0-9]+​

**Test this regex using java or C#.

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