Is String a Valid Number?
Understand how to validate whether a given string represents a valid number by applying a state machine method. Explore the process of analyzing each character to transition through states, handling signs, decimals, and invalid inputs. This lesson helps you implement an efficient O(n) time and O(1) space complexity solution for string numeric validation.
Statement
Given an input string, determine if a given string makes a valid number or not.
Notes:
- For simplicity, assume that white spaces are not present in the input.
- In case the input string is empty, the function should return TRUE.
Example
Input string | Validity |
4.325 | Valid number |
1.1.1 | Not a valid number |
222 | Valid number |
22. | Not a valid number |
0.1 | Valid number |
22.22. | Not a valid number |
1. | Not a valid number |
Example 1
Sample input
4.325
Expected output
true
Example 2
Sample input
1.1.1
Expected output
false