### Program to print prime numbers between 1 to n

`/**`

` `

`* C program to print all prime numbers between 1 to n`

` `

`*/`

`#include <stdio.h>`

`int`

`main()`

`{`

` `

`int`

`i, j, n, isPrime; `

`//isPrime is used as flag variable`

` `

`/* Reads upper limit to print prime */`

` `

`printf`

`(`

`"Find prime numbers between 1 to : "`

`);`

` `

`scanf`

`(`

`"%d"`

`, &n);`

` `

`printf`

`(`

`"\nAll prime numbers between 1 to %d are:\n"`

`, n);`

` `

`/* Finds all Prime numbers between 1 to n */`

` `

`for`

`(i=2; i<=n; i++)`

` `

`{`

` `

`/* Assume that the current number is Prime */`

` `

`isPrime = 1; `

` `

`/* Check if the current number i is prime or not */`

` `

`for`

`(j=2; j<=i/2; j++)`

` `

`{`

` `

`/*`

` `

`* If i is divisible by any number other than 1 and self`

` `

`* then it is not prime number`

` `

`*/`

` `

`if`

`(i%j==0)`

` `

`{`

` `

`isPrime = 0;`

` `

`break`

`;`

` `

`}`

` `

`}`

` `

`/* If the number is prime then print */`

` `

`if`

`(isPrime==1)`

` `

`{`

` `

`printf`

`(`

`"%d is Prime number\n"`

`, i);`

` `

`}`

` `

`}`

` `

`return`

`0;`

`} `

**Note:**For checking whether a number is Prime or not we just need to check that the number should not be divisible by any number between 2 to n-1. Apart from that you can also check between 2 to n/2. Since any number more than (n/2)+1 cannot be exactly divided by n except self n.

Output

Find prime numbers between 1 to : 100

All prime numbers between 1 to 100 are:

2 is Prime number

3 is Prime number

5 is Prime number

7 is Prime number

11 is Prime number

13 is Prime number

17 is Prime number

19 is Prime number

23 is Prime number

29 is Prime number

31 is Prime number

All prime numbers between 1 to 100 are:

2 is Prime number

3 is Prime number

5 is Prime number

7 is Prime number

11 is Prime number

13 is Prime number

17 is Prime number

19 is Prime number

23 is Prime number

29 is Prime number

31 is Prime number

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