Question
Validate if a given string is numeric.
Some examples:
"0" => true
" 0.1 " => true
"abc" => false
"1 a" => false
"2e10" => true
Note: It is intended for the problem statement to be ambiguous. You should gather all requirements up front before implementing one.
Stats
| Frequency | 5 |
| Difficulty | 2 |
| Adjusted Difficulty | unsolvable |
| Time to use | ---------- |
Ratings/Color = 1(white) 2(lime) 3(yellow) 4/5(red)
Solution
I am unable to solve this problem, but I found a quite good solution. I post the code below.
My code
public boolean isNumber(String s) {
s = s.trim();
if (s.length() > 0 && s.charAt(s.length() - 1) == 'e')
return false; //avoid "3e" which is false
String[] t = s.split("e");
if (t.length == 0 || t.length > 2) return false;
boolean res = valid(t[0], false);
if (t.length > 1) res = res && valid(t[1], true);
return res;
}
private boolean valid(String s, boolean hasDot) {
if (s.length() > 0 && (s.charAt(0) == '+' || s.charAt(0) == '-'))
s = s.substring(1); //avoid "1+", "+", "+."
char[] arr = s.toCharArray();
if (arr.length == 0 || s.equals(".")) return false;
for (int i = 0; i < arr.length; i++) {
if (arr[i] == '.') {
if (hasDot) return false;
hasDot = true;
} else if (!('0' <= arr[i] && arr[i] <= '9'))
return false;
}
return true;
}