top of page

Looking to master object-oriented and system design for tech interviews or career growth?

  • Improve your system design and machine coding skills.

  • Study with our helpful resources.

  • Prepare for technical interviews and advance your career.

**We're in beta mode and would love to hear your feedback.

Valid Number InterviewBit Solution

Problem: Valid Number

Problem Description:

Validate if a given string is numeric.


  • "0" => true

  • " 0.1 " => true

  • "abc" => false

  • "1 a" => false

  • "2e10" => true

Return 0 / 1 ( 0 for false, 1 for true ) for this problem

Clarify the question using “See Expected Output”

  • Is 1u ( which may be a representation for unsigned integers valid? For this problem, no.

  • Is 0.1e10 valid? Yes

  • -01.1e-10? Yes

  • Hexadecimal numbers like 0xFF? Not for the purpose of this problem

  • 3. (. not followed by a digit)? No

  • Can exponent have decimal numbers? 3e0.1? Not for this problem.

  • Is 1f ( floating point number with f as prefix ) valid? Not for this problem.

  • How about 1000LL or 1000L ( C++ representation for long and long long numbers )? Not for this problem.

  • How about integers preceded by 00 or 0? like 008? Yes for this problem

Solution Approach

First, try to find if it has any character other than digits or not.

If it doesn't have any character other than a digit, you can return true.

If it has some characters in it, try to check whether it denotes a sign, exponent or decimal. If yes then you are good to go return true, otherwise false.


In C++


bottom of page