Valid Numeric String

Valid Numeric String

You are working as a software engineer at a company that develops a financial trading platform. Your team is working on a new feature that allows users to enter numeric strings into a text field and have them parsed and converted into numbers.

One of the requirements for this feature is that the numeric strings must be valid. A valid numeric string must consist of:

• A sign character (either + or -).
• One or more digits.
• A decimal point . followed by one or more digits.
• An e or E followed by an integer.

For example, all the following are valid numeric strings:

"+"
"-"
"123"
"-123.456"
"1e10"
"-90E3"

while the following are not valid numeric strings:

"abc"
"1a"
"1e"
"e3"
"99e2.5"

You need to write a function that can be used to determine if a given string is a valid numeric string.