DIY: Valid Number

Solve the interview question "Valid Number" in this lesson.

Problem statement

Validate if a given string can be interpreted as a decimal number or not. Here is a list of characters that can appear in a valid decimal number:

  • Numbers - 0-9

  • Exponent - "e"

  • Positive/negative sign - "+"/"-"

  • Decimal point - "."

The context of these characters also matters in the input. Here are some examples:

"0" => true

" 0.1 " => true

".55" => true

"abc" => false

"1 a" => false

" -90e3 " => true

" 1e" => false

"e3" => false

" 6e-1" => true

" 99e2.5 " => false

" --6 " => false


The input will be a string, s. The following is an example input:

s = "53.5e93"


The output will be a Boolean value that represents whether the number is valid or not. For the above input, the output will be:


Coding exercise

For this coding exercise, you need to implement the isNumberValid(s) function, where s is the input string. The function should return a Boolean that shows whether the number is valid or not.

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