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# Check if a string consists only of special characters

Given string str of length N, the task is to check if the given string contains only special characters or not. If the string contains only special characters, then print â€śYesâ€ť. Otherwise, print â€śNoâ€ť.

Examples:

Input: str = â€ś@#\$&%!~â€ť
Output: Yes
Explanation:
Given string contains only special characters.
Therefore, the output is Yes.

Input: str = â€śGeeks4Geeks@#â€ť
Output: No
Explanation:
Given string contains alphabets, number, and special characters.
Therefore, the output is No.

Naive Approach: Iterate over the string and check if the string contains only special characters or not. Follow the steps below to solve the problem:

• Traverse the string and for each character, check if its ASCII value lies in the ranges [32, 47], [58, 64], [91, 96] or [123, 126]. If found to be true, it is a special character.
• Print Yes if all characters lie in one of the aforementioned ranges. Otherwise, print No.

Time Complexity: O(N)
Auxiliary Space: O(1)

Space-Efficient Approach: The idea is to use Regular Expression to optimize the above approach. Follow the steps below:

• Create the following regular expression to check if the given string contains only special characters or not.

regex = â€ś[^a-zA-Z0-9]+â€ť

where,

• [^a-zA-Z0-9] represents only special characters.
• + represents one or more times.
• Match the given string with the Regular Expression using Pattern.matcher() in Java
• Print Yes if the string matches with the given regular expression. Otherwise, print No.

Below is the implementation of the above approach:

## C++

 `// C++ program to check if the string` `// contains only special characters` `#include ` `#include ` `using` `namespace` `std;`   `// Function to check if the string contains only special characters.` `void` `onlySpecialCharacters(string str)` `{`   `  ``// Regex to check if the string contains only special characters.` `  ``const` `regex pattern(``"[^a-zA-Z0-9]+"``);`     `  ``// If the string` `  ``// is empty then print "No"` `  ``if` `(str.empty())` `  ``{` `     ``cout<< ``"No"``;` `     ``return` `;` `  ``}`   `  ``// Print "Yes" if the string contains only special characters` `  ``// matched the ReGex` `  ``if``(regex_match(str, pattern))` `  ``{` `    ``cout<< ``"Yes"``;` `  ``}` `  ``else` `  ``{` `    ``cout<< ``"No"``;` `  ``}` `}`   `// Driver Code` `int` `main()` `{` `  `  `  ``// Given string str` `  ``string str = ``"@#\$&%!~"``;` `  ``onlySpecialCharacters(str) ;`   `  ``return` `0;` `}`   `// This code is contributed by yuvraj_chandra`

## Java

 `// Java program to check if the string` `// contains only special characters`   `import` `java.util.regex.*;` `class` `GFG {`   `    ``// Function to check if a string` `    ``// contains only special characters` `    ``public` `static` `void` `onlySpecialCharacters(` `        ``String str)` `    ``{`   `        ``// Regex to check if a string contains` `        ``// only special characters` `        ``String regex = ``"[^a-zA-Z0-9]+"``;`   `        ``// Compile the ReGex` `        ``Pattern p = Pattern.compile(regex);`   `        ``// If the string is empty` `        ``// then print No` `        ``if` `(str == ``null``) {` `            ``System.out.println(``"No"``);` `            ``return``;` `        ``}`   `        ``// Find match between given string` `        ``// & regular expression` `        ``Matcher m = p.matcher(str);`   `        ``// Print Yes If the string matches` `        ``// with the Regex` `        ``if` `(m.matches())` `            ``System.out.println(``"Yes"``);` `        ``else` `            ``System.out.println(``"No"``);` `    ``}`   `    ``// Driver Code` `    ``public` `static` `void` `main(String args[])` `    ``{` `        ``// Given string str` `        ``String str = ``"@#\$&%!~"``;`   `        ``// Function Call` `        ``onlySpecialCharacters(str);` `    ``}` `}`

## Python3

 `# Python program to check if the string` `# contains only special characters` `import` `re`   `# Function to check if a string` `# contains only special characters` `def` `onlySpecialCharacters(``Str``):`   `    ``# Regex to check if a string contains` `    ``# only special characters` `    ``regex ``=` `"[^a-zA-Z0-9]+"`   `    ``# Compile the ReGex` `    ``p``=``re.``compile``(regex)`   `    ``# If the string is empty` `    ``# then print No` `    ``if``(``len``(``Str``) ``=``=` `0``):` `        ``print``(``"No"``)` `        ``return`   `    ``# Print Yes If the string matches` `    ``# with the Regex` `    ``if``(re.search(p, ``Str``)):` `        ``print``(``"Yes"``)` `    ``else``:` `        ``print``(``"No"``)`   `# Driver Code`   `# Given string str` `Str` `=` `"@#\$&%!~"`   `# Function Call` `onlySpecialCharacters(``Str``)`   `# This code is contributed by avanitrachhadiya2155`

## C#

 `// C# program to check if ` `// the string contains only ` `// special characters` `using` `System;` `using` `System.Text.RegularExpressions;  ` `class` `GFG{`   `// Function to check if a string` `// contains only special characters` `public` `static` `void` `onlySpecialchars(String str)` `{` `  ``// Regex to check if a string ` `  ``// contains only special ` `  ``// characters` `  ``String regex = ``"[^a-zA-Z0-9]+"``;`   `  ``// Compile the ReGex` `  ``Regex rgex = ``new` `Regex(regex);  `   `  ``// If the string is empty` `  ``// then print No` `  ``if` `(str == ``null``) ` `  ``{` `    ``Console.WriteLine(``"No"``);` `    ``return``;` `  ``}`   `  ``// Find match between given ` `  ``// string & regular expression` `  ``MatchCollection matchedAuthors = ` `                  ``rgex.Matches(str);    `   `  ``// Print Yes If the string matches` `  ``// with the Regex` `  ``if` `(matchedAuthors.Count != 0)` `    ``Console.WriteLine(``"Yes"``);` `  ``else` `    ``Console.WriteLine(``"No"``);` `}`   `// Driver Code` `public` `static` `void` `Main(String []args)` `{` `  ``// Given string str` `  ``String str = ``"@#\$&%!~"``;`   `  ``// Function Call` `  ``onlySpecialchars(str);` `}` `}`   `// This code is contributed by Princi Singh`

## Javascript

 ``

Output:

`Yes`

Time Complexity: O(N)
Auxiliary Space: O(1)

Another approach: This is simple approach in which just checking the string contain any alphabets and digits or not. If contains then print No else print Yes.

1. Take the a string str and call the function Check_Special_Chars passing string as parameter.

2. The function Check_Special_Chars takes a string as input and loops over each character in the string using a for loop.

3. Now in the inner loop check each character is an alphabet (both upper and lower case)  A to Z  ASCII value (65 to 90) and a to z  ASCII value(97 to 122) or not.

If the character is an alphabet, the function prints “No” and returns from the function.

4.The second inner for loop checks if the current character is a number (0 to 9)  ASCII value(48 to 57). If the character is a number, the function prints “No” and returns from the function.

5. If the function loops through the entire string without finding any alphabets or numbers, it means that the string only contains special characters. In this case, the function prints “Yes”.

Below the implementation of above approach.

## C++

 `// C++ program to check if the string` `// contains only special characters` `#include ` `using` `namespace` `std;`   `// Function to check if the string contains only special characters.` `void` `Check_Special_Chars(string s)` `{` `    ``// Looping over the string` `  ``for``(``int` `i = 0; i

## Java

 `import` `java.util.*;`   `class` `Main {` `    `  `    ``// Function to check if the string contains only special characters.` `    ``static` `void` `Check_Special_Chars(String s) {` `        ``// Looping over the string` `        ``for``(``int` `i = ``0``; i < s.length(); i++) {` `            ``// checking for a-z and A-Z characters` `            ``for``(``int` `k = ``0``; k < ``26``; k++) {` `                ``// if present then print No and return` `                ``if``(s.charAt(i) == (``char``)(k + ``65``) || s.charAt(i) == (``char``)(k + ``97``)) {` `                    ``System.out.println(``"No"``);` `                    ``return``;` `                ``}` `            ``}` `            ``// Checking for 0-9 characters` `            ``for``(``int` `k = ``0``; k < ``10``; k++) {` `                ``// if present then print No and return` `                ``if``(s.charAt(i) == (``char``)(k + ``48``)) {` `                    ``System.out.println(``"No"``);` `                    ``return``;` `                ``}` `            ``}` `        ``}` `        ``// if not present a-z, A-Z and 0-9, then only special character present and print Yes` `        ``System.out.println(``"Yes"``);` `    ``}` `    `  `    ``// Driver Code` `    ``public` `static` `void` `main(String[] args) {` `        ``// Given string str` `        ``String str = ``"@#\$&%!~"``;` `        ``Check_Special_Chars(str);` `    ``}` `}`

## Python3

 `class` `Main:` `    ``# Function to check if the string contains only special characters.` `    ``@staticmethod` `    ``def` `Check_Special_Chars(s):` `        ``# Looping over the string` `        ``for` `i ``in` `range``(``len``(s)):` `            ``# checking for a-z and A-Z characters` `            ``for` `k ``in` `range``(``26``):` `                ``# if present then print No and return` `                ``if` `s[i] ``=``=` `chr``(k ``+` `65``) ``or` `s[i] ``=``=` `chr``(k ``+` `97``):` `                    ``print``(``"No"``)` `                    ``return` `            ``# Checking for 0-9 characters` `            ``for` `k ``in` `range``(``10``):` `                ``# if present then print No and return` `                ``if` `s[i] ``=``=` `chr``(k ``+` `48``):` `                    ``print``(``"No"``)` `                    ``return` `        ``# if not present a-z, A-Z and 0-9, then only special character ` `        ``# present and print Yes` `        ``print``(``"Yes"``)` `    `  `    ``# Driver Code`   `        ``# Given string str` `str` `=` `"@#\$&%!~"` `Main.Check_Special_Chars(``str``)`

## C#

 `using` `System;`   `class` `Program ` `{` `  `  `    ``// Function to check if the string contains only special` `    ``// characters.` `    ``static` `void` `Check_Special_Chars(``string` `s)` `    ``{` `      `  `        ``// Looping over the string` `        ``for` `(``int` `i = 0; i < s.Length; i++) ` `        ``{` `          `  `            ``// checking for a-z and A-Z characters` `            ``for` `(``int` `k = 0; k < 26; k++) ` `            ``{` `              `  `                ``// if present then print No and return` `                ``if` `(s[i] == k + 65 || s[i] == k + 97) {` `                    ``Console.WriteLine(``"No"``);` `                    ``return``;` `                ``}` `            ``}` `            ``// Checking for 0-9 characters` `            ``for` `(``int` `k = 0; k < 10; k++)` `            ``{` `              `  `                ``// if present then print No and return` `                ``if` `(s[i] == k + 48) {` `                    ``Console.WriteLine(``"No"``);` `                    ``return``;` `                ``}` `            ``}` `        ``}` `      `  `        ``// if not present a-z, A-Z and 0-9, then only` `        ``// special character present and print Yes` `        ``Console.WriteLine(``"Yes"``);` `    ``}`   `    ``// Driver Code` `    ``static` `void` `Main(``string``[] args)` `    ``{` `        ``// Given string str` `        ``string` `str = ``"@#\$&%!~"``;` `        ``Check_Special_Chars(str);` `    ``}` `}`

## Javascript

 `// Function to check if the string contains only special characters.` `function` `Check_Special_Chars(s) {` `  ``// Looping over the string` `  ``for` `(let i = 0; i < s.length; i++) {` `    ``// checking for a-z and A-Z characters` `    ``for` `(let k = 0; k < 26; k++) {` `      ``// if present then print No and return` `      ``if` `(s[i] == String.fromCharCode(k + 65) || s[i] == String.fromCharCode(k + 97)) {` `        ``console.log(``"No"``);` `        ``return``;` `      ``}` `    ``}` `    ``// Checking for 0-9 characters` `    ``for` `(let k = 0; k < 10; k++) {` `      ``// if present then print No and return` `      ``if` `(s[i] == String.fromCharCode(k + 48)) {` `        ``console.log(``"No"``);` `        ``return``;` `      ``}` `    ``}` `  ``}` `  ``// if not present a-z, A-Z and 0-9, then only special character present and print Yes` `  ``console.log(``"Yes"``);` `}`   `// Driver Code` `let str = ``"@#\$&%!~"``;` `Check_Special_Chars(str);`

Output

`Yes`

Time Complexity: O(N)
Auxiliary Space: O(1)

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