Insert a character in String at a Given Position

Last Updated : 06 Nov, 2024

Given a string s, a character c and an integer position pos, the task is to insert the character c into the string s at the specified position pos.

Examples:

Input: s = "Geeks", c = 'A', pos = 3
Output: GeeAks
Input: s = "HelloWorld", c = '!', pos = 5
Output: Hello!World

Table of Content

[Approach-1] Using Built-In Methods

We will use library methods like string insert in C++, StringBuilder insert in Java and String Slicing in Python.

C++

// C++ program to insert a character at specific // position using Built in functions   #include <bits/stdc++.h> using namespace std; string insertChar(string &s, char c, int pos) {    // Insert character at specified position  s.insert(s.begin() + pos, c);  return s; } int main() {  string s = "Geeks";  cout << insertChar(s, 'A', 3);  return 0; }

Java

// Java program to insert a character at specific // position using Built in functions class GfG {  static String insertChar(StringBuilder sb, char c, int pos) {    // Insert character at specified position  sb.insert(pos, c);  return sb.toString();  }  public static void main(String[] args) {  StringBuilder sb = new StringBuilder("Geeks");  System.out.println(insertChar(sb, 'A', 3));  } }

Python

# Python program to insert a character at specific # position using Built in functions def insertChar(s, c, pos): # Insert character at specified position return s[:pos] + c + s[pos:] s = "Geeks" print(insertChar(s, 'A', 3))

// C# program to insert a character at specific // position using Built in functions using System; class GfG {  static string insertChar(string s, char c, int pos) {    // Insert character at specified position  return s.Substring(0, pos) + c + s.Substring(pos);  }  static void Main() {  string s = "Geeks";  Console.WriteLine(insertChar(s, 'A', 3));  } }

JavaScript

// JavaScript program to insert a character at  // specific position using Built in functions function insertChar(s, c, pos) {  // Insert character at specified position  return s.slice(0, pos) + c + s.slice(pos); } const s = "Geeks"; console.log(insertChar(s, 'A', 3));

Output

GeeAks

Time Complexity: O(n) where n is the length of the string.

[Approch-2] Using Custom Method

First, iterate through the given string, inserting all the characters into a new string until we reach the position where the given character needs to be inserted. At that position, insert the character, and then append the remaining characters from the input string to the new string.

C++

// C++ program to insert a character at specific // position using custom method #include <iostream> #include <string> using namespace std; string insertChar(string &s, char c, int pos) {  string res = "";  for (int i = 0; i < s.length(); i++) {    // Insert the character at   // the given position  if (i == pos)  res.push_back(c);    // Insert the original characters  res.push_back(s[i]);  }    // If the given pos is beyond the length,   // append the character at the end  if (pos >= s.length())   res.push_back(c);    return res; } int main() {  string s = "Geeks";  cout << insertChar(s, 'A', 3);  return 0; }

// C program to insert a character at specific // position using custom method #include <stdio.h> #include <string.h> void insertChar(char *s, char c, int pos, char *res) {  int length = strlen(s);  int j = 0;    for (int i = 0; i < length; i++) {    // Insert the character at the given position  if (i == pos)   res[j++] = c;    // Insert the original characters  res[j++] = s[i];  }  // If the given pos is beyond the length,  // append the character at the end  if (pos >= length)   res[j++] = c;  res[j] = '\0';  } int main() {  char s[] = "Geeks";  int len = strlen(s);  char res[len + 1];   insertChar(s, 'A', 3, res);   printf("%s\n", res);   return 0; }

Java

// Java program to insert a character at specific // position using custom method class GfG {  static String insertChar(String s, char c, int pos) {  StringBuilder res = new StringBuilder();  for (int i = 0; i < s.length(); i++) {    // Insert the character at the given position  if (i == pos)   res.append(c);    // Insert the original characters  res.append(s.charAt(i));  }    // If the given pos is beyond the length,   // append the character at the end  if (pos >= s.length())   res.append(c);    return res.toString();  }  public static void main(String[] args) {  String s = "Geeks";  System.out.println(insertChar(s, 'A', 3));  } }

Python

# Python program to insert a character at  # specific position using custom method def insertChar(s, c, pos): res = "" for i in range(len(s)): # Insert the character at  # the given position if i == pos: res += c # Insert the original characters res += s[i] # If the given pos is beyond the length,  # append the character at the end if pos >= len(s): res += c return res s = "Geeks" print(insertChar(s, 'A', 3))

// C# program to insert a character at specific position // using custom method using System; class GfG {  static string insertChar(string s, char c, int pos) {  string res = "";  for (int i = 0; i < s.Length; i++) {    // Insert the character at   // the given position  if (i == pos)   res += c;    // Insert the original characters  res += s[i];  }    // If the given pos is beyond the length,   // append the character at the end  if (pos >= s.Length)   res += c;    return res;  }  static void Main() {  string s = "Geeks";  Console.WriteLine(insertChar(s, 'A', 3));  } }

JavaScript

// JavaScript program to insert a character at  // specific position using custom method function insertChar(s, c, pos) {  let res = "";  for (let i = 0; i < s.length; i++) {    // Insert the character at   // the given position  if (i === pos)   res += c;    // Insert the original characters  res += s[i];  }    // If the given pos is beyond the length,   // append the character at the end  if (pos >= s.length)   res += c;    return res; } let s = "Geeks"; console.log(insertChar(s, 'A', 3));