Kth space-separated number from a given string
Last Updated :
23 Jul, 2025
Given a string S consisting of space-separated integers, the task is to extract the Kth number present in the string.
Note: The string contains at least K numbers in it.
Examples:
Input: S = "12 13 15", K= 3
Output: 15
Explanation: The 3rd integer in the above string is 15.
Input: S = "10 20 30 40", K = 2
Output: 20
Explanation: The 2nd integer in the above string is 20.
Naive Approach: The simplest approach to solve the problem is to traverse the string and keep a count of spaces encountered. Once, K - 1 spaces are encountered, print the number up to the next space as the required answer.
Below is the implementation of the above approach:
C++
// C++ Program for the above approach
#include <iostream>
using namespace std;
// Function to print kth integer
// in a given string
void print_kth_string(string s, int K)
{
// Size of the string
int N = s.length();
// Pointer for iteration
int i;
for (i = 0; i < N; i++) {
// If space char found
// decrement K
if (s[i] == ' ')
K--;
// If K becomes 1, the next
// string is the required one
if (K == 1)
break;
}
// Print the required number
while (i++ < N && s[i] != ' ')
cout << s[i];
}
// Driver Code
int main()
{
// Given string
string s("10 20 30 40");
// Given K
int K = 4;
// Function call
print_kth_string(s, K);
}
// Java program for the above approach
import java.io.*;
class GFG{
// Function to print kth integer
// in a given string
static void print_kth_string(String s, int K)
{
// Size of the string
int N = s.length();
// Pointer for iteration
int i;
for(i = 0; i < N; i++)
{
// If space char found
// decrement K
if (s.charAt(i) == ' ')
K--;
// If K becomes 1, the next
// string is the required one
if (K == 1)
break;
}
// Print the required number
while (i++ < N - 1 && s.charAt(i) != ' ')
System.out.print(s.charAt(i));
}
// Driver Code
public static void main (String[] args)
{
// Given string
String s = "10 20 30 40";
// Given K
int K = 4;
// Function call
print_kth_string(s, K);
}
}
// This code is contributed by sanjoy_62
# Python3 program for
# the above approach
# Function to print kth integer
# in a given string
def print_kth_string(s, K):
# Size of the string
N = len(s);
for i in range(0, N, 1):
# If space char found
# decrement K
if (s[i] == ' '):
K -= 1;
# If K becomes 1, the next
# string is the required one
if (K == 1):
break;
# Print required number
while (i < N):
if(s[i] != ' '):
print(s[i], end = "");
i += 1;
# Driver Code
if __name__ == '__main__':
# Given string
s = "10 20 30 40";
# Given K
K = 4;
# Function call
print_kth_string(s, K);
# This code is contributed by Rajput-Ji
// C# program for the above approach
using System;
class GFG{
// Function to print kth integer
// in a given string
static void print_kth_string(string s, int K)
{
// Size of the string
int N = s.Length;
// Pointer for iteration
int i;
for(i = 0; i < N; i++)
{
// If space char found
// decrement K
if (s[i] == ' ')
K--;
// If K becomes 1, the next
// string is the required one
if (K == 1)
break;
}
// Print the required number
while (i++ < N - 1 && s[i] != ' ')
Console.Write(s[i]);
}
// Driver Code
public static void Main ()
{
// Given string
string s = "10 20 30 40";
// Given K
int K = 4;
// Function call
print_kth_string(s, K);
}
}
// This code is contributed by sanjoy_62
<script>
// javascript program for the above approach
// Function to print kth integer
// in a given string
function print_kth_string( s , K) {
// Size of the string
var N = s.length;
// Pointer for iteration
var i;
for (i = 0; i < N; i++) {
// If space char found
// decrement K
if (s.charAt(i) == ' ')
K--;
// If K becomes 1, the next
// string is the required one
if (K == 1)
break;
}
// Print the required number
while (i++ < N - 1 && s.charAt(i) != ' ')
document.write(s.charAt(i));
}
// Driver Code
// Given string
var s = "10 20 30 40";
// Given K
var K = 4;
// Function call
print_kth_string(s, K);
// This code is contributed by umadevi9616
</script>
Time Complexity: O(N), where N is the length of the string.
Auxiliary Space: O(1)
Stringstream Approach: The idea is to use stringstream in C++ which associates a string object with a stream and allowing us to read from the string as if it were a stream (like cin).
Below is the implementation of the above approach:
C++
// C++ program for the above approach
#include <bits/stdc++.h>
using namespace std;
// Function to print Kth integer
// from a given string
void print_kth_string(string str, int K)
{
// Split input into words
// using stringstream
stringstream iss(str);
// Stores individual words
string kth;
// Extract words from stream
while (iss >> kth && K) {
K--;
// If kth position
// is reached
if (K == 0) {
cout << kth;
break;
}
}
}
// Driver Code
int main()
{
// Given string
string s("10 20 30 40");
// Given K
int K = 4;
// Function call
print_kth_string(s, K);
}
// Java program for
// the above approach
import java.util.*;
class GFG{
// Function to print Kth integer
// from a given String
static void print_kth_String(String str,
int K)
{
// Split input into words
// using split
String[] iss = str.split(" ");
K--;
System.out.print(iss[K]);
}
// Driver Code
public static void main(String[] args)
{
// Given String
String s = ("10 20 30 40");
// Given K
int K = 4;
// Function call
print_kth_String(s, K);
}
}
// This code is contributed by Rajput-Ji
# Python3 program for the above approach
# Function to print Kth integer
# from a given string
def print_kth_string(str1, K):
# Split input into words
# using stringstream
st = str1.split(" ")
# Stores individual words
print(st[K - 1])
# Driver Code
if __name__ == '__main__':
# Given string
s = "10 20 30 40"
# Given K
K = 4
# Function call
print_kth_string(s, K)
# This code is contributed by SURENDRA_GANGWAR
// C# program for
// the above approach
using System;
class GFG{
// Function to print Kth integer
// from a given String
static void print_kth_String(String str,
int K)
{
// Split input into words
// using split
String[] iss = str.Split(' ');
K--;
Console.Write(iss[K]);
}
// Driver Code
public static void Main(String[] args)
{
// Given String
String s = ("10 20 30 40");
// Given K
int K = 4;
// Function call
print_kth_String(s, K);
}
}
// This code is contributed by Rajput-Ji
// Function to print Kth integer from a given string
function print_kth_String(str, K) {
// Split input into words using split
let iss = str.split(" ");
K--;
console.log(iss[K]);
}
// Driver Code
let s = "10 20 30 40";
let K = 4;
// Function call
print_kth_String(s, K);
Time Complexity: O(N), where N is the length of the string.
Auxiliary Space: O(1)
Built-in String Functions based Approach: The idea is to use strtok() function to extract the string at the key. Use c_str() function to get the char pointer reference of an array of the characters.
Below is the implementation of the above approach:
C++
// C++ program of the above approach
#include <cstring>
#include <iostream>
using namespace std;
// Function to extract integer at key
// position in the given string
void print_kth_string(string str, int K)
{
// strtok(): Extracts the number at key
// c_str(): Type cast string to char*
char* s = strtok((char*)str.c_str(),
" ");
while (K > 1) {
// Get the token at position -> key
s = strtok(NULL, " ");
K--;
}
// Print the kth integer
cout << string(s) << " ";
}
// Driver Code
int main()
{
// Given string
string s("10 20 30 40");
// Given K
int K = 2;
// Function call
print_kth_string(s, K);
return 0;
}
// Java program of the
// above approach
import java.util.*;
class GFG{
// Function to extract integer
// at key position in the given String
static void print_kth_String(String str,
int K)
{
// StringTokenizer(): Extracts
// the number at key
// c_str(): Type cast
// String to char*
StringTokenizer st =
new StringTokenizer(str);
int count = 1;
while (st.hasMoreTokens() && K > 0 )
{
if(count == K)
System.out.println(st.nextToken());
count++;
st.nextToken();
}
}
// Driver Code
public static void main(String[] args)
{
// Given String
String s = ("10 20 30 40");
// Given K
int K = 2;
// Function call
print_kth_String(s, K);
}
}
// This code is contributed by 29AjayKumar
# Python code of the above approach
import re
# Function to extract integer at key
# position in the given string
def print_kth_string(string, K):
# split the string using space as a separator
s = re.split(" ", string)
# return the Kth element of the split string
return s[K-1]
# Driver Code
if __name__ == '__main__':
# Given string
s = "10 20 30 40"
# Given K
K = 2
# Function call
print(print_kth_string(s, K))
// C# program of the
// above approach
using System;
class GFG{
// Function to extract integer
// at key position in the given String
static void print_kth_String(String str,
int K)
{
// StringTokenizer(): Extracts
// the number at key
// c_str(): Type cast
// String to char*
String[] iss = str.Split(' ');
K--;
Console.Write(iss[K]);
}
// Driver Code
public static void Main(String[] args)
{
// Given String
String s = ("10 20 30 40");
// Given K
int K = 2;
// Function call
print_kth_String(s, K);
}
}
// This code is contributed by Rajput-Ji
// Function to extract integer at key position in the given string
function print_kth_string(str, K) {
// Split input string into words using split
let words = str.split(" ");
// Print the Kth integer
console.log(words[K-1]);
}
// Driver Code
let s = "10 20 30 40";
let K = 2;
// Function call
print_kth_string(s, K);
Time Complexity: O(N), where N is the length of the string.
Auxiliary Space: O(1)
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