Basic String Operations with Implementation
In this post, we will look into some of the basic String operations such as:
- Accessing characters by index in a string.
- Inserting character into a String.
- Modifying character in String
- Deletion of Character in String
- Concatenating strings (combining multiple strings into one).
- Finding the length of a string
- Comparing strings for equality or lexicographical order
Let us consider the basic String operations one by one.
Accessing characters by index in a string.
To access any character in a String, we need:
- A non-empty string (say “str”)
- A position/index of the character from where it is to be accessed. (say “k”)
Using these two, the character can be easily accessed using the below syntax:
char ch = str[k];
OR
char ch = str.charAt(k);
Below is the implementation of the above approach:
// CPP code for accessing an element by index
#include <iostream>
#include <string>
using namespace std;
// Function to demonstrate insert
char accessCharByIndex(string str, int k)
{
// return the character at Kth index
// in the string str
return str[k];
}
// Driver code
int main()
{
string str("w3wiki ");
int k = 4;
cout << accessCharByIndex(str, k) << endl;
return 0;
}
#include <stdio.h>
#include <string.h>
// Function to demonstrate accessing character by index
char accessCharByIndex(char* str, int k)
{
// Return the character at the kth index in the string
return str[k];
}
// Driver code
int main()
{
char str[] = "w3wiki ";
int k = 4;
printf("%c\n", accessCharByIndex(str, k));
return 0;
}
public class GFG {
// Function to demonstrate accessCharByIndex
public static char accessCharByIndex(String str, int k) {
// Return the character at the k-th index in the string str
return str.charAt(k);
}
// Driver code
public static void main(String[] args) {
String str = "w3wiki ";
int k = 4;
System.out.println(accessCharByIndex(str, k));
}
}
# Function to access an element by index
def access_char_by_index(s, k):
# Return the character at the kth index in the string s
return s[k]
# Driver code
def main():
string_value = "w3wiki "
index = 4
print(access_char_by_index(string_value, index))
# Run the main function
if __name__ == "__main__":
main()
using System;
class Program {
// Function to access a character by index
static char AccessCharByIndex(string str, int k)
{
// Return the character at the k-th index
return str[k];
}
static void Main()
{
string str = "w3wiki ";
int k = 4;
Console.WriteLine(AccessCharByIndex(str, k));
}
}
// Function to demonstrate access by index
function accessCharByIndex(str, k) {
// Return the character at the kth index in the string str
return str[k];
}
// Driver code
let str = "w3wiki ";
let k = 4;
console.log(accessCharByIndex(str, k));
Output
s
Inserting Character/String into an String.
To insert any Character/String in a String, we need:
- A character/string that is to be inserted in the string (say “ch”)
- A position/index of the Character/String where it is to be inserted. (say “k”)
Below is the implementation of the above approach:
// CPP code for Inserting character/string into an String.
#include <iostream>
#include <string>
using namespace std;
// Function to demonstrate insert
void insertDemo(string str, string ch, int k)
{
// Inserts ch at kth index of str
str.insert(k, ch);
cout << "Modified String : " << str << endl;
}
// Driver code
int main()
{
string str("BeginnerBeginner ");
string ch = "for";
int k = 5;
cout << "Original String : " << str << endl;
insertDemo(str, ch, k);
return 0;
}
#include <stdio.h>
#include <string.h>
void insertDemo(char* str, const char* ch, int k) {
int len1 = strlen(str);
int len2 = strlen(ch);
// Shift characters to the right to make space for ch
for (int i = len1; i >= k; i--) {
str[i + len2] = str[i];
}
// Insert ch at kth index of str
for (int i = 0; i < len2; i++) {
str[k + i] = ch[i];
}
printf("Modified String: %s\n", str);
}
int main() {
char str[] = "BeginnerBeginner ";
char ch[] = "for";
int k = 5;
printf("Original String: %s\n", str);
insertDemo(str, ch, k);
return 0;
}
public class Main {
public static void main(String[] args) {
String str = "BeginnerBeginner ";
String ch = "for";
int k = 5;
System.out.println("Original String: " + str);
insertDemo(str, ch, k);
}
// Function to demonstrate insert
public static void insertDemo(String str, String ch, int k) {
// Inserts ch at kth index of str
StringBuilder sb = new StringBuilder(str);
sb.insert(k, ch);
String modifiedString = sb.toString();
System.out.println("Modified String: " + modifiedString);
}
}
# Python program for the above approach
# Function to demonstrate insert
def insert_demo(s, ch, k):
# Inserts ch at kth index of s
modified_string = s[:k] + ch + s[k:]
print("Modified String:", modified_string)
# Driver code
if __name__ == "__main__":
original_string = "BeginnerBeginner "
ch_to_insert = "for"
index_to_insert = 5
print("Original String:", original_string)
insert_demo(original_string, ch_to_insert, index_to_insert)
# This code is contributed by Susobhan Akhuli
using System;
class Program
{
// Function to demonstrate insert
static string InsertDemo(string str, string ch, int k)
{
// Inserts ch at kth index of str
return str.Insert(k, ch);
}
// Driver code
static void Main()
{
string str = "BeginnerBeginner ";
string ch = "for";
int k = 5;
Console.WriteLine("Original String: " + str);
string modifiedString = InsertDemo(str, ch, k);
Console.WriteLine("Modified String: " + modifiedString);
}
}
// JavaScript equivalent of the given Java code
// Function to demonstrate insert
function insertDemo(str, ch, k) {
// Inserts ch at kth index of str
let modifiedString = str.slice(0, k) + ch + str.slice(k);
console.log("Modified String: " + modifiedString);
}
// Main function
function main() {
let str = "BeginnerBeginner ";
let ch = "for";
let k = 5;
console.log("Original String: " + str);
insertDemo(str, ch, k);
}
// Call the main function
main();
Output
Original String : BeginnerBeginner Modified String : w3wiki
Modifying character in String
To modify any Character in a String, we need:
- A character that is to replaced in the string (say “ch”)
- A position/index of the Character where it is to be replaced at. (say “k”)
Below is the implementation of the above approach:
#include <iostream>
#include <string>
int main()
{
// Get the string
std::string str = "Beginner Gor Beginner";
// Get the index
int index = 6;
// Get the character
char ch = 'F';
// Print the original string
std::cout << "Original String = " << str << std::endl;
str.replace(index, 1, 1, ch);
// Print the modified string
std::cout << "Modified String = " << str << std::endl;
return 0;
}
#include <stdio.h>
#include <string.h>
int main()
{
// Define the string
char str[] = "Beginner Gor Beginner";
// Define the index
int index = 6;
// Define the character
char ch = 'F';
// Print the original string
printf("Original String = %s\n", str);
// Modify the string
str[index] = ch;
// Print the modified string
printf("Modified String = %s\n", str);
return 0;
}
public class GFG {
public static void main(String args[])
{
// Get the String
String str = "Beginner Gor Beginner";
// Get the index
int index = 6;
// Get the character
char ch = 'F';
// Print the original string
System.out.println("Original String = " + str);
str = str.substring(0, index) + ch
+ str.substring(index + 1);
// Print the modified string
System.out.println("Modified String = " + str);
}
}
# Function to replace a character at a specific index in a string
def replace_character_at_index(string, index, new_character):
# Convert string to list of characters to allow modification
string_list = list(string)
# Replace character at the specified index
string_list[index] = new_character
# Convert back to string and return
return ''.join(string_list)
# Main function
def main():
# Original string
original_string = "Beginner Gor Beginner"
# Index to replace character
index = 6
# New character
new_character = 'F'
# Print original string
print("Original String =", original_string)
# Replace character at the specified index
modified_string = replace_character_at_index(
original_string, index, new_character)
# Print modified string
print("Modified String =", modified_string)
# Entry point of the program
if __name__ == "__main__":
main()
using System;
public class GFG
{
public static void Main()
{
// Get the String
string str = "Beginner Gor Beginner";
// Get the index
int index = 6;
// Get the character
char ch = 'F';
// Print the original string
Console.WriteLine("Original String = " + str);
// Modify the string
str = str.Substring(0, index) + ch + str.Substring(index + 1);
// Print the modified string
Console.WriteLine("Modified String = " + str);
}
}
let str = "Beginner Gor Beginner"; // Get the string
let index = 6; // Get the index
let ch = 'F'; // Get the character
console.log("Original String = " + str); // Print the original string
// Modify the string
str = str.substr(0, index) + ch + str.substr(index + 1);
console.log("Modified String = " + str); // Print the modified string
Output
Original String = Beginner Gor Beginner Modified String = Beginner For Beginner
Deletion of character in String
To delete any Character in a String, we need:
- A character that is to deleted in the string (say “ch”)
Below is the implementation of the above approach:
// C++ program to remove a particular character
// from a string.
#include <bits/stdc++.h>
using namespace std;
void removeChar(char* s, char c)
{
int j, n = strlen(s);
for (int i = j = 0; i < n; i++)
if (s[i] != c)
s[j++] = s[i];
s[j] = '\0';
}
int main()
{
char s[] = "w3wiki";
removeChar(s, 'g');
cout << s;
return 0;
}
#include <stdio.h>
#include <string.h>
void removeChar(char* s, char c) {
int i, j, n = strlen(s);
for (i = j = 0; i < n; i++) {
if (s[i] != c) {
s[j++] = s[i];
}
}
s[j] = '\0';
}
int main() {
char s[] = "w3wiki";
removeChar(s, 'g');
printf("%s", s);
return 0;
}
public class Main {
// Function to remove a particular character
// from a character array
// Parameters:
// - s: the character array from which
// the character will be removed
// - c: the character to be removed
public static void removeChar(char[] s, char c) {
// Initialize a pointer j to keep track of the
// position where characters are being moved
int j = 0;
// Loop through the character array
for (int i = 0; i < s.length; i++) {
// If the current character is
// not the one to be removed
if (s[i] != c) {
// Move the character to the
// position indicated by j
s[j++] = s[i];
}
}
// Fill the remaining positions with null characters ('\0')
while (j < s.length) {
s[j++] = '\0';
}
}
public static void main(String[] args) {
// Input string as a character array
char[] s = "w3wiki".toCharArray();
// Remove character 'g' from the string
removeChar(s, 'g');
// Print the modified string
System.out.println(s);
}
}
//This code is added By prachi
# Python program to remove a particular character
# from a string.
def removeChar(s, c):
# Initialize variables
n = len(s)
j = 0
# Iterate through each character of the string
for i in range(n):
# If the character is not equal to
# the target character, keep it
if s[i] != c:
s[j] = s[i]
j += 1
# Add null character at the end of the modified string
s = s[:j]
return s
if __name__ == "__main__":
s = "w3wiki"
# Convert string to list of characters for modification
s = list(s)
s = removeChar(s, 'g')
# Convert list of characters back to string for printing
print(''.join(s))
#this code is contributed by Adarsh .
// JavaScript program for the above approach
// Function to remove a particular character from a character array
// Parameters:
// - s: the character array from which the character will be removed
// - c: the character to be removed
function removeChar(s, c) {
// Initialize a pointer j to keep track of the position where characters are being moved
let j = 0;
// Loop through the character array
for (let i = 0; i < s.length; i++) {
// If the current character is not the one to be removed
if (s[i] !== c) {
// Move the character to the position indicated by j
s[j++] = s[i];
}
}
// Fill the remaining positions with null characters ('\0')
while (j < s.length) {
s[j++] = '\0';
}
}
// Input string as a character array
let s = "w3wiki".split('');
// Remove character 'g' from the string
removeChar(s, 'g');
// Print the modified string
console.log(s.join(''));
// This code is contributed by Susobhan Akhuli
Output
eeksforeeks
Concatenating strings (combining multiple strings into one).
To concatenate any String to a String, we need:
- A string that is to appended with the string (say “ch”)
Below is the implementation of the above approach:
// C++ Program for string
// concatenation using '+' operator
#include <iostream>
using namespace std;
// Driver code
int main()
{
string init("this is init");
string add(" added now");
// Appending the string.
init = init + add;
cout << init << endl;
return 0;
}
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
char init[] = "this is init";
char add[] = " added now";
char* result = (char*)malloc(strlen(init) + strlen(add) + 1);
strcpy(result, init);
strcat(result, add);
printf("%s\n", result);
free(result);
return 0;
}
public class Main {
public static void main(String[] args) {
String init = "this is init";
String add = " added now";
// Appending the string.
init = init + add;
System.out.println(init);
}
}
def main():
init = "this is init"
add = " added now"
# Concatenate strings
result = init + add
# Print the result
print(result)
# Call the main function
if __name__ == "__main__":
main()
// Define the main function
function main() {
let init = "this is init";
let add = " added now";
// Appending the string.
init = init + add;
console.log(init);
}
// Call the main function
main();
Output
this is init added now
Finding the length/size of a string
To find the length of the String, we need:
- A string for which the length/size is to be determined (say “str”)
Below is the implementation of the above approach:
// C++ program to find length
// of a string
#include <iostream>
#include <string.h>
using namespace std;
// Driver code
int main()
{
// String obj
string str = "w3wiki";
// size of string object using size() method
cout << str.size() << endl;
return 0;
}
#include <stdio.h>
#include <string.h>
int main()
{
// String
char str[] = "w3wiki";
// Length of string using strlen() function
int length = strlen(str);
printf("%d\n", length);
return 0;
}
public class Main {
public static void main(String[] args)
{
// String object
String str = "w3wiki";
// Size of string object using length() method
System.out.println(str.length());
}
}
// This code is contributed by Utkarsh
# Main function
def main():
# String object
str = "w3wiki"
# Size of string object using len() function
print(len(str))
# Calling the main function
if __name__ == "__main__":
main()
// JavaScript program to find length
// of a string
// String
let str = "w3wiki";
// size of string using length property
console.log(str.length);
Output
13
Comparing Strings for Equality
To compare strings, Define a function to compare values with the following conditions :
- if (string1 != string2) it returns a False.
- if both the strings are equal lexicographically (string1 == string2), it returns True.
Below is the implementation of the above approach:
#include <iostream>
using namespace std;
bool stringCompare(const string& str1, const string& str2) {
int l1 = str1.length();
int l2 = str2.length();
int lmin = min(l1, l2);
for (int i = 0; i < lmin; i++) {
int str1_ch = static_cast<int>(str1[i]);
int str2_ch = static_cast<int>(str2[i]);
if (str1_ch != str2_ch) {
return false;
}
}
if (l1 != l2) {
return false;
} else {
return true;
}
}
int main() {
string string1 = "w3wiki";
string string2 = "Practice";
string string3 = "Beginner";
string string4 = "Beginner";
cout << "Comparing " << string1 << " and " << string2 << " : "
<< stringCompare(string1, string2) << endl;
cout << "Comparing " << string3 << " and " << string4 << " : "
<< stringCompare(string3, string4) << endl;
cout << "Comparing " << string1 << " and " << string4 << " : "
<< stringCompare(string1, string4) << endl;
return 0;
}
#include <stdio.h>
#include <stdbool.h>
#include <string.h>
// This function compares two strings lexicographically
bool stringCompare(const char* str1, const char* str2) {
int l1 = strlen(str1);
int l2 = strlen(str2);
int lmin = (l1 < l2) ? l1 : l2;
for (int i = 0; i < lmin; i++) {
int str1_ch = (int)str1[i];
int str2_ch = (int)str2[i];
if (str1_ch != str2_ch) {
return false;
}
}
// Edge case for strings with different lengths
if (l1 != l2) {
return false;
}
// If none of the above conditions is true,
// it implies both the strings are equal
return true;
}
// Driver function to test the above program
int main() {
const char* string1 = "w3wiki";
const char* string2 = "Practice";
const char* string3 = "Beginner";
const char* string4 = "Beginner";
// Comparing string1 and string2
printf("Comparing %s and %s: %s\n", string1, string2,
stringCompare(string1, string2) ? "true" : "false");
// Comparing string3 and string4
printf("Comparing %s and %s: %s\n",
string3, string4, stringCompare(string3, string4) ?
"true" : "false");
// Comparing string1 and string4
printf("Comparing %s and %s: %s\n",
string1, string4, stringCompare(string1, string4) ?
"true" : "false");
return 0;
}
// Java program to Compare two strings
// lexicographically
public class GFG {
// This method compares two strings
// lexicographically without using
// library functions
public static Boolean stringCompare(String str1,
String str2)
{
int l1 = str1.length();
int l2 = str2.length();
int lmin = Math.min(l1, l2);
for (int i = 0; i < lmin; i++) {
int str1_ch = (int)str1.charAt(i);
int str2_ch = (int)str2.charAt(i);
if (str1_ch != str2_ch) {
return false;
}
}
// Edge case for strings like
// String 1="Beginner" and String 2="w3wiki"
if (l1 != l2) {
return false;
}
// If none of the above conditions is true,
// it implies both the strings are equal
else {
return true;
}
}
// Driver function to test the above program
public static void main(String args[])
{
String string1 = new String("w3wiki");
String string2 = new String("Practice");
String string3 = new String("Beginner");
String string4 = new String("Beginner");
// Comparing for String 1 < String 2
System.out.println(
"Comparing " + string1 + " and " + string2
+ " : " + stringCompare(string1, string2));
// Comparing for String 3 = String 4
System.out.println(
"Comparing " + string3 + " and " + string4
+ " : " + stringCompare(string3, string4));
// Comparing for String 1 > String 4
System.out.println(
"Comparing " + string1 + " and " + string4
+ " : " + stringCompare(string1, string4));
}
}
def string_compare(str1, str2):
l1 = len(str1)
l2 = len(str2)
lmin = min(l1, l2)
for i in range(lmin):
str1_ch = ord(str1[i])
str2_ch = ord(str2[i])
if str1_ch != str2_ch:
return 0
if l1 != l2:
return 0
else:
return 1
string1 = "w3wiki"
string2 = "Practice"
string3 = "Beginner"
string4 = "Beginner"
print("Comparing", string1, "and", string2, ":",
string_compare(string1, string2))
print("Comparing", string3, "and", string4, ":",
string_compare(string3, string4))
print("Comparing", string1, "and", string4, ":",
string_compare(string1, string4))
#this code is contributed by Adarsh.
// Function to compare two strings
function stringCompare(str1, str2) {
const l1 = str1.length;
const l2 = str2.length;
const lmin = Math.min(l1, l2);
// Iterate over the strings and compare characters
for (let i = 0; i < lmin; i++) {
const str1_ch = str1.charCodeAt(i);
const str2_ch = str2.charCodeAt(i);
if (str1_ch !== str2_ch) {
return 0; // If characters don't match, return 0
}
}
// If lengths are not equal, return 0
if (l1 !== l2) {
return 0;
} else {
return 1; // Otherwise, return 1
}
}
const string1 = "w3wiki";
const string2 = "Practice";
const string3 = "Beginner";
const string4 = "Beginner";
console.log("Comparing", string1, "and",
string2, ":", stringCompare(string1, string2));
console.log("Comparing", string3, "and",
string4, ":", stringCompare(string3, string4));
console.log("Comparing", string1, "and",
string4, ":", stringCompare(string1, string4));
// This code is contributed by Utkarsh.
Output
Comparing w3wiki and Practice : 0 Comparing Beginner and Beginner : 1 Comparing w3wiki and Beginner : 0
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