How to validate image file extension using Regular Expression
Given string str, the task is to check whether the given string is a valid image file extension or not by using Regular Expression.
The valid image file extension must specify the following conditions:
- It should start with a string of at least one character.
- It should not have any white space.
- It should be followed by a dot(.).
- It should be end with any one of the following extensions: jpg, jpeg, png, gif, bmp.
Examples:
Input: str = “abc.png”
Output: true
Explanation:
The given string satisfy all the above mentioned conditions.
Input: str = “im.jpg”
Output: true
Explanation:
The given string satisfy all the above mentioned conditions.
Input: str = “.gif”
Output: false
Explanation:
The given string doesn’t start with image file name(required at least one character). Therefore, it is not a valid image file extension.
Approach: This problem can be solved by using regular expression.
- Get the String.
- Create a regular expression to check the valid image file extension as mentioned below:
regex = “([^\\s]+(\\.(?i)(jpe?g|png|gif|bmp))$)”;
- Where:
- ( represents the starting of group 1.
- [^\\s]+ represents the string must contain at least one character.
- ( represents the starting of group 2.
- \\. Represents the string should follow by a dot(.).
- (?i) represents the string ignore the case-sensitive.
- ( represents the starting of group3.
- jpe?g|png|gif|bmp represents the string end with jpg or jpeg or png or gif or bmp extension.
- ) represents the ending of the group 3.
- ) represents the ending of the group 2.
- $ represents the end of the string.
- ) represents the ending of the group 1.
- Match the given string with regular expression. In Java, this can be done by using Pattern.matcher().
- Return true if the given string matched with the regular expression, else return false.
Below is the implementation of the above approach:
C++
// C++ program to validate the // image file extension using Regular Expression #include <iostream> #include <regex> using namespace std; // Function to validate the image file extension. bool imageFile(string str) { // Regex to check valid image file extension. const regex pattern( "[^\\s]+(.*?)\\.(jpg|jpeg|png|gif|JPG|JPEG|PNG|GIF)$" ); // If the image file extension // is empty return false if (str.empty()) { return false ; } // Return true if the image file extension // matched the ReGex if (regex_match(str, pattern)) { return true ; } else { return false ; } } // Driver Code int main() { // Test Case 1: string str1 = "abc.png" ; cout << imageFile(str1) << endl; // Test Case 2: string str2 = "im.jpg" ; cout << imageFile(str2) << endl; // Test Case 3: string str3 = ".gif" ; cout << imageFile(str3) << endl; // Test Case 4: string str4 = "abc.mp3" ; cout << imageFile(str4) << endl; // Test Case 5: string str5 = " .jpg" ; cout << imageFile(str5) << endl; return 0; } // This code is contributed by yuvraj_chandra |
Java
// Java program to check valid // image file extension using regex import java.util.regex.*; class GFG { // Function to validate image file extension . public static boolean imageFile(String str) { // Regex to check valid image file extension. String regex = "([^\\s]+(\\.(?i)(jpe?g|png|gif|bmp))$)" ; // Compile the ReGex Pattern p = Pattern.compile(regex); // If the string is empty // return false if (str == null ) { return false ; } // Pattern class contains matcher() method // to find matching between given string // and regular expression. Matcher m = p.matcher(str); // Return if the string // matched the ReGex return m.matches(); } // Driver code public static void main(String args[]) { // Test Case 1: String str1 = "abc.png" ; System.out.println(imageFile(str1)); // Test Case 2: String str2 = "im.jpg" ; System.out.println(imageFile(str2)); // Test Case 3: String str3 = ".gif" ; System.out.println(imageFile(str3)); // Test Case 4: String str4 = "abc.mp3" ; System.out.println(imageFile(str4)); // Test Case 5: String str5 = " .jpg" ; System.out.println(imageFile(str5)); } } |
Python3
# Python3 program to validate # image file extension using regex import re # Function to validate # image file extension . def imageFile( str ): # Regex to check valid image file extension. regex = "([^\\s]+(\\.(?i)(jpe?g|png|gif|bmp))$)" # Compile the ReGex p = re. compile (regex) # If the string is empty # return false if ( str = = None ): return False # Return if the string # matched the ReGex if (re.search(p, str )): return True else : return False # Driver code # Test Case 1: str1 = "abc.png" print (imageFile(str1)) # Test Case 2: str2 = "im.jpg" print (imageFile(str2)) # Test Case 3: str3 = ".gif" print (imageFile(str3)) # Test Case 4: str4 = "abc.mp3" print (imageFile(str4)) # Test Case 5: str5 = " .jpg" print (imageFile(str5)) # This code is contributed by avanitrachhadiya2155 |
C#
// C# program to validate the //image file extension //using Regular Expressions using System; using System.Text.RegularExpressions; class GFG { // Main Method static void Main( string [] args) { // Input strings to Match //image file extension string [] str={ "abc.png" , "im.jpg" , ".gif" , "abc.mp3" , " .jpg" }; foreach ( string s in str) { Console.WriteLine( imageFile(s) ? "true" : "false" ); } Console.ReadKey(); } // method containing the regex public static bool imageFile( string str) { string strRegex = @"([^\s]+(\.(?i)(jpe?g|png|gif|bmp))$)" ; Regex re = new Regex(strRegex); if (re.IsMatch(str)) return ( true ); else return ( false ); } } // This code is contributed by Rahul Chauhan |
Javascript
// Javascript program to validate // Image File using Regular Expression // Function to validate the // Image File function imageFile(str) { // Regex to check valid // Image File let regex = new RegExp(/[^\s]+(.*?).(jpg|jpeg|png|gif|JPG|JPEG|PNG|GIF)$/); // if str // is empty return false if (str == null ) { return "false" ; } // Return true if the str // matched the ReGex if (regex.test(str) == true ) { return "true" ; } else { return "false" ; } } // Driver Code // Test Case 1: let str1 = "abc.png" ; console.log(imageFile(str1)); // Test Case 2: let str2 = "im.jpg" ; console.log(imageFile(str2)); // Test Case 3: let str3 = ".gif" ; console.log(imageFile(str3)); // Test Case 4: let str4 = "abc.mp3" ; console.log(imageFile(str4)); // Test Case 5: let str5 = " .jpg" ; console.log(imageFile(str5)); // This code is contributed by Rahul Chauhan |
true true false false false
Time Complexity: O(N) for each testcase, where N is the length of the given string.
Auxiliary Space: O(1)
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