Given a string, now as of we all know that the task is to check whether a string contains only alphabets. Now we will be iterating character by character and checking the corresponding ASCII value attached to it. If not found means there is some other character other than “a-z” or “A-Z”. If we traverse the whole string and land up on finding all characters in a string within this domain pool then the string is surely only alphabetic.
Illustrations:
Input : Lazyroar Output : True Input : Geeks4Geeks Output : False Input : null Output : False
In this article, the characters of the string are checked one by one using their ASCII values.
Algorithm:
- Get the string
- Match the string:
- Check if the string is empty or not. If empty, return false
- Check if the string is null or not. If null, return false.
- If the string is neither empty nor null, then check the string characters one by one for alphabet using ASCII values.
- Return true if matched
Example 1:
Java
// Java Program to Check if a String Contains Only Alphabets// Using ASCII values// Importing required classesimport java.util.*;// Class 1// Main classclass GFG { // Main driver method public static void main(String[] args) { // Creating object of helper class Helper h = new Helper(); // Print statement System.out.println( h.isStringOnlyAlphabet("neveropen")); }}// Class 2// Helper classclass Helper { public static boolean isStringOnlyAlphabet(String str) { // If string is empty or null if (str == null || str.equals("")) { // Return false return false; } // If we reach here we have character/s in string for (int i = 0; i < str.length(); i++) { // Getting character at indices // using charAt() method char ch = str.charAt(i); if ((!(ch >= 'A' && ch <= 'Z')) && (!(ch >= 'a' && ch <= 'z'))) { return false; } } // String is only alphabetic return true; }} |
Output
true
Complexity Analysis:
- Time Complexity: O(N), where N is the length of the string.
- Auxiliary Space: O(1), no extra space required so it is a constant.
Example 2:
Java
// Java program to check if String contains only Alphabets// Using ASCII Values// Main classclass GFG { // Method 1 // To check String for only Alphabets public static boolean isStringOnlyAlphabet(String str) { // If there is no string if (str == null || str.equals("")) { return false; } // Iterating as now we encounter string // using length() method for (int i = 0; i < str.length(); i++) { char ch = str.charAt(i); // Checking for any other aphabetic character // present in string if ((!(ch >= 'A' && ch <= 'Z')) && (!(ch >= 'a' && ch <= 'z'))) { // Then string is not only alphabetic return false; } } // If we reach here, it means // string is only aphabetic return true; } // Method 2 // Main method public static void main(String[] args) { // Checking for True case System.out.println("Test Case 1:"); String str1 = "Lazyroar"; System.out.println("Input: " + str1); System.out.println("Output: " + isStringOnlyAlphabet(str1)); // Checking for String with numeric characters System.out.println("\nTest Case 2:"); String str2 = "Geeks4Geeks"; System.out.println("Input: " + str2); System.out.println("Output: " + isStringOnlyAlphabet(str2)); // Checking for null String System.out.println("\nTest Case 3:"); String str3 = null; System.out.println("Input: " + str3); System.out.println("Output: " + isStringOnlyAlphabet(str3)); // Checking for empty String System.out.println("\nTest Case 4:"); String str4 = ""; System.out.println("Input: " + str4); System.out.println("Output: " + isStringOnlyAlphabet(str4)); }} |
Output
Test Case 1: Input: Lazyroar Output: true Test Case 2: Input: Geeks4Geeks Output: false Test Case 3: Input: null Output: false Test Case 4: Input: Output: false
Complexity Analysis:
- Time Complexity: O(N), where N is the length of the string.
- Auxiliary Space: O(1), no extra space required so it is a constant.
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