How To Print 1 to 100 Numbers Without Using Any Loop statements

1. Overview

this tutorial, We'll learn how to print 1 to 100 without using loop statements.

Couple of year back, My friend was asked this question in interview. He has given many tries but finally he could give the answer using recursive approach. This interview question will be asked to check how we understand the concepts and how we are using it on problem.

Actually this can be done using any loop statements such as For Loop or While Loop. But, we'll see using normal and recursive approach.

2. Normal Approach

In the normal approach, printing numbers from 1 to 100 is done by for or while loop running from pointer 1 to 100.

2.1 for loop

A comprehensive guide to For Loop with Examples.

for (int i = 1; i <= 100; i++) {
 System.out.println(i);
}

2.2 While loop

A comprehensive guide to While Loop with Examples.

int j = 1;
while (j <= 100) {
 System.out.println(j);
 j++;
}

3. Recursive Approach

Recursion: A method calls itself again and again to resolve a problem that is until a given condition is met.

We will implement in Java, C++ and Python programming languages.
Here recursive approach starts from number 100 to 1 because it creates a stack for each self call. First call for 100 will be placed in the stack and 99 next ... and so on.. for 1 st num method call be on top of stack. Once seeing the program, you will be getting clear idea.

3.1 Java

public void printNnumber(int toNumber) {
 if (toNumber > 0) {
  printNnumber(toNumber - 1);
  System.out.print(toNumber + " ");
 }
 return;
}

3.2 C++

public: 
void printNnumber(unsigned int toNumber) 
{ 
    if(toNumber > 0) 
    { 
        printNnumber(toNumber - 1); 
        cout << toNumber << " "; 
    } 
    return; 
} 
}; 

3.3 Python

indentation is important in Python.

def printNnumber(toNumber): 
    if toNumber > 0: 
        printNnumber(toNumber - 1) 
        print(toNumber, end = ' ') 

4. Output

Output for all programs above should be same. We have tested all these programs in latest versions.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 

5. Conclusion

In this tutorial, we've seen printing the numbers from 1 to any without using loop.

Further article, implementation is done in java, c++ and python 3.

The same logic can be used on any pattern such print your name 100 times without using for loop or print pattern without loop, print number series etc.

All codes are shown here are available on GitHub.