# C program to print strong numbers between 1 to n

Write a C program to print Strong numbers between 1 to n. C program to print all strong numbers between a given range. Logic to print strong numbers in a given range in C program.

Example

Input

`Input upper limit: 1000`

Output

```Strong numbers between 1-1000:
1, 2, 145```

## Required knowledge

Must know –

### What is a Strong number?

Strong number is a special number whose sum of factorial of digits is equal to the original number. For example: 145 is strong number. Since, `1! + 4! + 5! = 145`

## Logic to print Strong numbers between 1 to n

Step by step descriptive logic to print strong numbers from 1 to n.

1. Input upper limit to print strong number from user. Store it in a variable say end.
2. Run a loop from 1 to end, increment 1 in each iteration. Structure of the loop should be similar to `for(i=1; i<=end; i++)`.
3. For each iteration inside loop check i for strong number. Print the value of i if it is a strong number.

Let us convert the above logic to a C program.

## Program to print strong numbers between 1 to n

``````/**
* C program to print all Strong Numbers between 1 to n
*/

#include <stdio.h>

int main()
{
int i, j, cur, lastDigit, end;
long long fact, sum;

/* Input upper limit from user */
printf("Enter upper limit: ");
scanf("%d", &end);

printf("All Strong numbers between 1 to %d are:\n", end);

/* Iterate from 1 to end */
for(i=1; i<=end; i++)
{
/* Number to check for strong number */
cur = i;

sum = 0;

/* Find the sum of factorial of digits */
while(cur > 0)
{
fact = 1ll;
lastDigit = cur % 10;

/* Find factorial of last digit of current num. */
for( j=1; j<=lastDigit; j++)
{
fact = fact * j;
}

sum += fact;

cur /= 10;
}

/* Print 'i' if it is strong number */
if(sum == i)
{
printf("%d, ", i);
}
}

return 0;
}``````

Once, you got the logic of printing strong numbers between 1 to n. You can easily modify the logic to find strong numbers in any given range. Below program illustrates how to print strong numbers in a given range.

## Program to print strong numbers in given range

``````/**
* C program to print Strong numbers in given range
*/

#include <stdio.h>

int main()
{
int i, j, cur, lastDigit, start, end;
long long fact, sum;

/* Input lower and upper limit from user */
printf("Enter lower limit: ");
scanf("%d", &start);
printf("Enter upper limit: ");
scanf("%d", &end);

printf("All Strong numbers between %d to %d are:\n", start, end);

/* Iterate from 1 to end */
for(i=start; i<=end; i++)
{
/* Number to check for strong number */
cur = i;

sum = 0;

/* Find the sum of factorial of digits */
while(cur > 0)
{
fact = 1ll;
lastDigit = cur % 10;

/* Find factorial of last digit of current num. */
for( j=1; j<=lastDigit; j++)
{
fact = fact * j;
}

sum += fact;

cur /= 10;
}

/* Print 'i' if it is strong number */
if(sum == i)
{
printf("%d, ", i);
}
}

return 0;
}``````

Output

```Enter lower limit: 1
Enter upper limit: 100000
1, 2, 145, 40585,```

Happy coding 😉

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