# How to determine if the prime number and the primes in a segment are

Source: Internet
Author: User

The so-called primes are those numbers that cannot be divisible by any integer except 1 and itself. For example, 17 is the prime number, because it is not the same as any integer divisible by 2~16. Therefore, determine whether an integer nnum is a prime number. It is only necessary to remove the nnum from each integer between the 2~nnum-1. If none of them are divisible, then nnum is a prime number.

Here we can also use a simple way to simply be 2~√m between each integer to remove it.

`#include  <stdio.h> #include  <math.h>int isprimenum (int nnum); Int main () {     int nNum;    int nFlag = 0;     printf ("Enter a number to determine if prime: \ n"); &NBSP;&NBSP;&NBSP;&NBSP;SCANF ("%d",  &nnum);     if (Nflag = isprimenum (nnum))         printf ("This is a prime number.") \ n ");     else        printf (" This is not a prime number.) \ n ");     return 0;} Int isprimenum (Int nnum) {    int nflag = 0;     int ntmp;    int i;    ntmp=sqrt (NNum);     for (i=2;i<=ntmp;i++)         if (nNum%i==0)              break;    if (I&GT;NTMP)  & Nbsp;      return nflag = 1;    else         retrun nflag = 0;}`

How to determine if the prime number and the primes in a segment are

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