Check if a string represents a hexadecimal number

In computer science, hexadecimal is a 16-based number system. It uses 16 different symbols, including the ten decimal digits 0 to 9 and the six letters A, B, C, D, E and F to represent numbers from 0 to 15. In this article, we will discuss how to check if a string represents a hexadecimal number.

Problem Statement

Given a string, the task is to check whether it represents a valid hexadecimal number.

method

We can solve this problem by iterating the characters in the string and checking if they belong to a valid hex character set. Valid hexadecimal characters are numbers from 0 to 9 and letters from A to F (regardless of uppercase or lowercase). If all characters in the string belong to this character set, then the string represents a valid hexadecimal number.

Example

This is the C code implementation of the above method:

#include <iostream>
#include <string>

using namespace std;

bool isHexadecimal(string s) {
   int n = s.length();
   
   for (int i = 0; i < n; i++) {
      if (!isxdigit(s[i])) {
         return false;
      }
   }
   
   return true;
}

int main() {
   string s1 = "ABCD1234";
   string s2 = "12G4F5";
   
   if (isHexadecimal(s1)) {
      cout << s1 << " represents a valid hexadecimal number." << endl;
   } else {
      cout << s1 << " does not represent a valid hexadecimal number." << endl;
   }
   
   if (isHexadecimal(s2)) {
      cout << s2 << " represents a valid hexadecimal number." << endl;
   } else {
      cout << s2 << " does not represent a valid hexadecimal number." << endl;
   }
   
   return 0;
}

Output

Running the above code will output

ABCD1234 represents a valid hexadecimal number.
12G4F5 does not represent a valid hexadecimal number.

time complexity

The time complexity of the solution is O(N), where N is the length of the string.

Space complexity

The space complexity of the solution is O(1).

In the above code, we define a function isHexadecimal, which accepts a string as input and returns true when the string represents a valid hexadecimal number, otherwise it returns false. We use the isxdigit function to check if each character in the string belongs to a valid hexadecimal character set.

Test Case

Let us take two strings s1 = "ABCD1234" and s2 = "12G4F5". The string s1 represents a valid hexadecimal number because all characters in the string belong to the valid hexadecimal character set. On the other hand, string s2 does not represent a valid hexadecimal number because it contains a character 'G' which is not a valid hexadecimal character.

in conclusion

In summary, we can easily check if a string represents a valid hexadecimal number by iterating over the characters of the string and checking if they belong to a valid hexadecimal character set.

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