// C++ program for the above approach #include    #include  using namespace std; void printStrings(string phNo int i  unordered_map<char string> hm  string str) {  if (i == phNo.length())  {  cout << str << ' ';  return;  }  string s = hm[phNo[i]];  for (int j = 0; j < s.length(); j++)  {  str.push_back(s[j]);  printStrings(phNo i+1 hm str);  str.pop_back();  } } void printStringForNumber(string phNo) {  unordered_map<char string> hm = {  {'2' 'ABC'}  {'3' 'DEF'}  {'4' 'GHI'}  {'5' 'JKL'}  {'6' 'MNO'}  {'7' 'PQRS'}  {'8' 'TUV'}  {'9' 'WXYZ'}  {'1' '1'}  {'0' '0'}  };  string str;  printStrings(phNo 0 hm str); } int main() {  printStringForNumber('23');  return 0; } // This code is contributed by codebraxnzt 

// Java program to print all possible key strings // that can be used to dial a phone number. import java.util.HashMap; class ConvertToString {  // A Recursive function to print all combinations  // that can be used to dial a given number.  // phNo ==> Given Phone Number  // i ==> Current digit of phNo to be processed  // hm ==> Stores characters that can be used to  // to dial a digit.  // str ==> Current output string  static void printStrings(String phNo int i  HashMap<Character String> hm  StringBuilder str)  {  // If all digits are processed print output  // string  if (i == phNo.length())  {  System.out.print(str + ' ');  return;  }  // Get current digit of phNo and recur for all  // characters that can be used to dial it.  String s = hm.get(phNo.charAt(i));  for (int j = 0; j < s.length(); j++)  {  str.append(s.charAt(j));  printStrings(phNo i+1 hm str);  str.deleteCharAt(str.length()-1);  }  }  // Prints all possible combinations of strings that  // can be used to dial c[].  static void printStringForNumber(String phNo)  {  // Create a HashMap  HashMap<Character String> hm =  new HashMap<Character String>();  // For every digit store characters that can  // be used to dial it.  hm.put('2' 'ABC');  hm.put('3' 'DEF');  hm.put('4' 'GHI');  hm.put('5' 'JKL');  hm.put('6' 'MNO');  hm.put('7' 'PQRS');  hm.put('8' 'TUV');  hm.put('9' 'WXYZ');  hm.put('1' '1');  hm.put('0' '0');  // Create a string to store a particular output  // string  StringBuilder str = new StringBuilder();  // Call recursive function  printStrings(phNo 0 hm str);  }  // Driver code to test above methods  public static void main(String args[])  {  // Prints  printStringForNumber('23');  } } 

def print_strings(ph_no i hm s): if i == len(ph_no): print(s end=' ') return for c in hm[ph_no[i]]: print_strings(ph_no i+1 hm s+c) def print_string_for_number(ph_no): hm = { '2': 'ABC' '3': 'DEF' '4': 'GHI' '5': 'JKL' '6': 'MNO' '7': 'PQRS' '8': 'TUV' '9': 'WXYZ' '1': '1' '0': '0' } s = '' print_strings(ph_no 0 hm s) print_string_for_number('23') 

using System; using System.Collections.Generic; class Program {  static void printStrings(string phNo int i  Dictionary<char string> hm  string str)  {  if (i == phNo.Length)  {  Console.Write(str + ' ');  return;  }  string s = hm[phNo[i]];  for (int j = 0; j < s.Length; j++)  {  str += s[j];  printStrings(phNo i+1 hm str);  str = str.Remove(str.Length-1);  }  }  static void printStringForNumber(string phNo)  {  Dictionary<char string> hm = new Dictionary<char string>  {  {'2' 'ABC'}  {'3' 'DEF'}  {'4' 'GHI'}  {'5' 'JKL'}  {'6' 'MNO'}  {'7' 'PQRS'}  {'8' 'TUV'}  {'9' 'WXYZ'}  {'1' '1'}  {'0' '0'}  };  string str = '';  printStrings(phNo 0 hm str);  }  static void Main(string[] args) {  printStringForNumber('23');  } } 

function printStrings(phNo i hm s) {  if (i === phNo.length) {  console.log(s + ' ');  return;  }  for (let j = 0; j < hm[phNo[i]].length; j++) {  s += hm[phNo[i]][j];  printStrings(phNo i+1 hm s);  s = s.slice(0 -1);  } } function printStringForNumber(phNo) {  let hm = {  '2': 'ABC'  '3': 'DEF'  '4': 'GHI'  '5': 'JKL'  '6': 'MNO'  '7': 'PQRS'  '8': 'TUV'  '9': 'WXYZ'  '1': '1'  '0': '0'  };  let s = '';  printStrings(phNo 0 hm s); } printStringForNumber('23');