Program to print all substrings of a given string

Given a string as an input. We need to write a program that will print all non-empty substrings of that given string.

Examples : 

Input :  abcd
Output :  a 
          b
          c
          d
          ab
          bc
          cd
          abc
          bcd
          abcd

We can run three nested loops, the outermost loop picks starting character, mid loop considers all characters on right of the picked character as ending character of substring. The innermost loop prints characters from currently picked starting point to picked ending point. 

C++

// C++ program to print all possible
// substrings of a given string

#include<bits/stdc++.h>
using namespace std;

// Function to print all sub strings
void subString(char str[], int n)
{
    // Pick starting point
    for (int len = 1; len <= n; len++)
    {
        // Pick ending point
        for (int i = 0; i <= n - len; i++)
        {
            //  Print characters from current
            // starting point to current ending
            // point.
            int j = i + len - 1;
            for (int k = i; k <= j; k++)
                cout << str[k];

            cout << endl;
        }
    }
}

// Driver program to test above function
int main()
{
    char str[] = "abc";
    subString(str, strlen(str));
    return 0;
}

Java

//Java program to print all possible
// substrings of a given string

class GFG {

// Function to print all sub strings
    static void subString(char str[], int n) {
        // Pick starting point
        for (int len = 1; len <= n; len++) {
            // Pick ending point
            for (int i = 0; i <= n - len; i++) {
                //  Print characters from current
                // starting point to current ending
                // point.
                int j = i + len - 1;
                for (int k = i; k <= j; k++) {
                    System.out.print(str[k]);
                }

                System.out.println();
            }
        }
    }

// Driver program to test above function
    public static void main(String[] args) {
        char str[] = {'a', 'b', 'c'};
        subString(str, str.length);

    }
}
// This code is contributed by PrinciRaj1992

Python

# Python3 program to print all possible
# substrings of a given string


# Function to print all sub strings
def subString(Str,n):

    # Pick starting point
    for Len in range(1,n + 1):

        # Pick ending point
        for i in range(n - Len + 1):

            # Print characters from current
            # starting point to current ending
            # point.
            j = i + Len - 1

            for k in range(i,j + 1):
                print(Str[k],end="")
            print()

# Driver program to test above function
Str = "abc"
subString(Str,len(Str))

# This code is contributed by mohit kumar

C#

// C# program to print all possible
// substrings of a given string
using System;

public class GFG {

    // Function to print all sub
    // strings
    static void subString(string str,
                               int n)
    {

        // Pick starting point
        for (int len = 1; len <= n;
                               len++)
        {
            // Pick ending point
            for (int i = 0;
                    i <= n - len; i++)
            {
                // Print characters
                // from current
                // starting point to
                // current ending
                // point.
                int j = i + len - 1;

                for (int k = i; k <= j;
                                    k++)
                    Console.Write(str[k]);

                Console.WriteLine();
            }
        }
    }

    // Driver program to test
    // above function
    static public void Main ()
    {
        string str = "abc";
        subString(str, str.Length);
    }
}

// This code is contributed by anuj_67.

PHP

<?php
// PHP program to print all possible
// substrings of a given string

// Function to print all sub strings
function subString($str, $n)
{

    // Pick starting point
    for ($len = 1; $len <= $n; $len++)
    {

        // Pick ending point
        for ($i = 0; $i <= $n - $len; $i++)
        {

            // Print characters from current
            // starting point to current ending
            // point.
            $j = $i + $len - 1;
            for ($k = $i; $k <= $j; $k++)
                echo $str[$k];

            echo "\n";
        }
    }
}

    // Driver Code
    $str = "abc";
    subString($str, strlen($str));

// This code is contributed by nitin mittal.
?>

Output:

a
b
c
ab
bc
abc

Method 2 (Using substr() function)
s.substr(i, len) prints substring of length ‘len’ starting from index i in string s.

C++

// C++ program to print all possible
// substrings of a given string
#include<bits/stdc++.h>
using namespace std;

// Function to print all sub strings
void subString(string s, int n)
{
    // Pick starting point in outer loop
    // and lengths of different strings for
    // a given starting point
    for (int i = 0; i < n; i++)
        for (int len = 1; len <= n - i; len++)
            cout << s.substr(i, len) << endl;
}

// Driver program to test above function
int main()
{
    string s = "abcd";
    subString(s,s.length());
    return 0;
}

Java

// Java program to print all substrings of a string
public class GFG {

    // Function to print all substring
    public static void SubString(String str, int n)
    {
       for (int i = 0; i < n; i++)
           for (int j = i+1; j <= n; j++)

                // Please refer below article for details
                // of substr in Java
                // https://www.geeksforgeeks.org/java-lang-string-substring-java/
                System.out.println(str.substring(i, j));
    }

    public static void main(String[] args)
    {
        String str = "abcd";
        SubString(str, str.length());
    }
}

// This code is contributed by ASHISH KUMAR PATEL

Python3

# Python program to print all possible
# substrings of a given string

# Function to print all sub strings
def subString(s, n):
    # Pick starting point in outer loop
    # and lengths of different strings for
    # a given starting point
    for i in range(n):
        for len in range(i+1,n+1):
            print(s[i: len]);

# Driver program to test above function
s = "abcd";
subString(s,len(s));

# This code is contributed by princiraj1992

C#

// C# program to print all substrings of a string
using System;

public class GFG {

    // Function to print all substring
    public static void SubString(String str, int n)
    {
    for (int i = 0; i < n; i++)
        for (int j = 1; j <= n - i; j++)

                // Please refer below article for details
                // of substr in Java
                // https://www.geeksforgeeks.org/java-lang-string-substring-java/
                Console.WriteLine(str.Substring(i, j));
    }

    public static void Main()
    {
        String str = "abcd";
        SubString(str, str.Length);
    }
}

/*This code is contributed by PrinciRaj1992*/

Output:

a
ab
abc
abcd
b
bc
bcd
c
cd
d

This method is contributed by Ravi Shankar Rai

Method 3 (Generate a substring using previous substring)

C++

/*
 * C++ program to print all possible
 * substrings of a given string
 * without checking for duplication.
 */

#include<bits/stdc++.h>
using namespace std;

/*
 * Function to print all (n * (n + 1)) / 2
 * substrings of a given string s of length n.
 */
void printAllSubstrings(string s, int n)
{
    /*
     * Fix start index in outer loop.
     * Reveal new character in inner loop till end of string.
     * Print till-now-formed string.
     */
    for (int i = 0; i < n; i++)
    {
        char temp[n - i + 1];
        int tempindex = 0;
        for (int j = i; j < n; j++)
        {
            temp[tempindex++] = s[j];
            temp[tempindex] = '\0';
            printf("%s\n", temp);
        }
    }
}

// Driver program to test above function
int main()
{
    string s = "Geeky";
    printAllSubstrings(s, s.length());
    return 0;
}

Java

// Java program to print all possible
// subStrings of a given String
// without checking for duplication.
import java.io.*;

class GFG{

// Function to print all (n * (n + 1)) / 2
// subStrings of a given String s of length n.
public static void printAllSubStrings(String s,
                                      int n)
{

    // Fix start index in outer loop.
    // Reveal new character in inner
    // loop till end of String.
    // Print till-now-formed String.
    for(int i = 0; i < n; i++)
    {
        char[] temp = new char[n - i + 1];
        int tempindex = 0;

        for(int j = i; j < n; j++)
        {
            temp[tempindex++] = s.charAt(j);
            temp[tempindex] = '\0';
            System.out.println(temp);
        }
    }
}

// Driver code
public static void main(String[] args)
{
    String s = "Geeky";

    printAllSubStrings(s, s.length());
}
}

// This code is contributed by avanitrachhadiya2155

Python3

'''
* Python3 program to prall possible
* substrings of a given string
* without checking for duplication.
'''


'''
* Function to prall (n * (n + 1)) / 2
* substrings of a given string s of length n.
'''
def printAllSubstrings(s, n):

    # Fix start index in outer loop.
    # Reveal new character in inner loop till end of string.
    # Prtill-now-formed string.
    for i in range(n):
        temp=""
        for j in range(i,n):
            temp+=s[j]
            print(temp)

# Driver program to test above function

s = "Geeky"
printAllSubstrings(s, len(s))

# This code is contributed by shubhamsingh10

C#

// C# program to print all possible
// subStrings of a given String
// without checking for duplication.
using System;

class GFG{

// Function to print all (n * (n + 1)) / 2
// subStrings of a given String s of length n.
public static void printAllSubStrings(String s, int n)
{
    // Fix start index in outer loop.
    // Reveal new character in inner
    // loop till end of String.
    // Print till-now-formed String.
    for(int i = 0; i < n; i++)
    {
        char[] temp = new char[n - i + 1];
        int tempindex = 0;

        for(int j = i; j < n; j++)
        {
            temp[tempindex++] = s[j];
            temp[tempindex] = '\0';
            Console.WriteLine(temp);
        }
    }
}

// Driver code
public static void Main()
{
    String s = "Geeky";

    printAllSubStrings(s, s.Length);
}
}

// This code is contributed by Shubhamsingh10

Output:

G
Ge
Gee
Geek
Geeky
e
ee
eek
eeky
e
ek
eky
k
ky
y

Method 4 (using three nested loops)

C

// C program for the above approach
#include <stdio.h>
void printSubstrings(char str[])
{

    // outermost for loop
    // this is for the selection
    // of starting point
    for (int start = 0; str[start] != '\0'; start++) {

        // 2nd for loop is for selection
        // of ending point
        for (int end = start; str[end] != '\0'; end++) {

            // 3rd loop is for printing from
            // starting point to ending point
            for (int i = start; i <= end; i++) {
                printf("%c", str[i]);
            }

            // changing the line after printing
            // from starting point to ending point
            printf("\n");
        }
    }
}

// Driver Code
int main()
{

    // code
    char str[] = { 'a', 'b', 'c', 'd', '\0' };
    // calling the method to print the substring
    printSubstrings(str);
    return 0;
}

C++

// CPP program for the above approach
#include <iostream>
using namespace std;
void printSubstrings(string str)
{

    // finding the length of the string
    int n = str.length();

    // outermost for loop
    // this is for the selection
    // of starting point
    for (int i = 0; i < n; i++) {

        // 2nd for loop is for selection
        // of ending point
        for (int j = i; j < n; j++) {

            // 3rd loop is for printing from
            // starting point to ending point
            for (int k = i; k <= j; k++) {
                cout << str[k];
            }

            // changing the line after printing
            // from starting point to ending point
            cout << endl;
        }
    }
}

// Driver Code
int main()
{
    string str = "abcd";
    printSubstrings(str);

    return 0;
}

Java

// Java program for the above approach
import java.io.*;

class GFG {
    public static void printSubstrings(String str)
    {

        // finding the length of the string
        int n = str.length();

        // outermost for loop
        // this is for the selection
        // of starting point
        for (int i = 0; i < n; i++) {

            // 2nd for loop is for selection
            // of ending point
            for (int j = i; j < n; j++) {

                // 3rd loop is for printing from
                // starting point to ending point
                for (int k = i; k <= j; k++) {
                    System.out.print(str.charAt(k));
                }

                // changing the line after printing
                // from starting point to ending point
                System.out.println();
            }
        }
    }

    // Driver Code
    public static void main(String[] args)
    {
        String str = "abcd";

        // calling method for printing substring
        printSubstrings(str);
    }
}

Python3

# Python program for the above approach
def printSubstrings(string, n):

  # this is for the selection
    # of starting point
    for i in range(n):

        # 2nd for loop is for selection
        # of ending point
        for j in range(i, n):

            # 3rd loop is for printing from
            # starting point to ending point
            for k in range(i, (j + 1)):
                print(string[k], end="")

            # changing the line after printing
            # from starting point to ending point
            print()

# Driver Code
string = "abcd"
# calling the method to print the substring
printSubstrings(string, len(string))

Output

a
ab
abc
abcd
b
bc
bcd
c
cd
d

Time complexity: O(N³)

Space complexity: O(1), where N is the length of the input string

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