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C Program to Print All Natural Numbers from 1 to N in Iterative Methods

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First N natural numbers

C program to print all the natural numbers from 1 to N can be written in both iterative and recursive methods. In the iterative method, the task can be performed by using for loop, while loop and do-while loop.

  Here, all the C programs using different loops have been covered to print the natural numbers. The algorithm, time complexity and pseudocode of the program have also been added.






1. Algorithm to Print First N Natural Numbers


1. Take a natural number n as input.

2. Set another variable i=1

3. Iterate i from 1 to n

4. Print value of i in each iteration




2. Pseudocode to Print First N Natural Numbers


Input : A natural number $n$

Output : All the natural numbers from 1 to $n$

1. Procedure printUptoN($n$):

2. $i\leftarrow1$

3. Repeat

4. Print $i$

5. $i \leftarrow i+1$

6. Until $i \leq n$

7. End Procedure





3. Time complexity to Print First N Natural Numbers


Time Complexity: O(n)

Here, $n$ is the no. of natural numbers.





4. C Program & output to Print First N Natural Numbers

Code has been copied
/******************************************************************
                alphabetacoder.com
 C program to print all natual numbers from 1 to n  using for loop
*******************************************************************/

#include <stdio.h>

int main() {
    int n, i;
    //take input of the number upto which 
    // natural numbers will be printed
    printf("Enter the upper limit = ");
    scanf("%d", & n);

    // iterate from 1 to n and print the number
    printf("First %d natural numbers are : ", n);
    for (i = 1; i <= n; i++)
        printf("%d ", i);
    return 0;
}

Output

Case 1:

Enter the upper limit = 10

First 10 natural numbers are : 1 2 3 4 5 6 7 8 9 10


Case 2:

Enter the upper limit = 5

First 5 natural numbers are : 1 2 3 4 5

/**************************************************
                alphabetacoder.com
 C program to print all natual numbers from 1 to 
 n using while loop
**************************************************/

#include <stdio.h>

int main() {
    int n, i;
    //take input of the number upto which 
    // natural numbers will be printed
    printf("Enter the upper limit = ");
    scanf("%d", & n);

    // iterate from 1 to n and print the number
    printf("First %d natural numbers are : ", n);
    i = 1;
    while (i <= n) {
        printf("%d ", i);
        i++;
    }
    return 0;
}

Output

Case 1:

Enter the upper limit = 10

First 10 natural numbers are : 1 2 3 4 5 6 7 8 9 10


Case 2:

Enter the upper limit = 5

First 5 natural numbers are : 1 2 3 4 5

/**************************************************
                alphabetacoder.com
 C program to print all natual numbers from 1 to 
 n using do-while loop
**************************************************/

#include <stdio.h>

int main() {
    int n, i;
    //take input of the number upto which 
    // natural numbers will be printed
    printf("Enter the upper limit = ");
    scanf("%d", & n);

    // iterate from 1 to n and print the number
    printf("First %d natural numbers are : ", n);
    i = 1;
    do {
        printf("%d ", i);
        i++;
    } while (i <= n);

    return 0;
}

Output

Case 1:

Enter the upper limit = 10

First 10 natural numbers are : 1 2 3 4 5 6 7 8 9 10


Case 2:

Enter the upper limit = 5

First 5 natural numbers are : 1 2 3 4 5




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