C language prime, how to tell if a number is prime in C language?

You can add a 0 to the end of the array, but you can't have a 0 in the middle. Then change it to something like this:

#include

int main()

int n, i,k, a=;There is an extra 0n=0; Assign an initial value of 0 to n

while(a[n]) When a[n] is true, i.e. a[n] is not 0

k=sqrt(a[n]);Here we use a[n]for(i=2; i<=k;i++)

if(n%i==0)break;

if(i>k)

printf("%d ",n);

n++;n is incremented by 1 so that a[n] is the next number.

The program is not very well written.

First of all, how can you use your printf without include.

Secondly, the return value of the main() function is int, but you don't have a return.

Again, what does n=a mean, I haven't seen k is int, but the return value of sqrt() is double.

Finally, the for loop seems to only be able to judge one number, if it could.

lz has learned arrays, and he can still write such a bad program, which is admired!

After all, men become big things. Laying a good foundation is key!

Don't forget!

#include ""

void main()

If an integer is prime, then only it is divisible by 1 and itself, so there is only 2, and if it exceeds 2, then it is certainly not prime.

if (flag==2) else}

#include

#include

#include

int prime(int a) defines a function to determine whether a is prime or not

if (flag==2)

return 1;*If a is a prime number, the flag should be 2 and the return value is 1*

elsereturn 0;*If a is not prime, the flag is greater than 2 and the return value is 0*

* (This part is supplemental, the prime function can be simplified to :)int prime(int a).)

return flag;}*/

int main()

For details, please refer to:

Prime numbers areOnlyA positive integer divisible by 1 and itself. For example, 2 is a prime number: 2 1=2, 2 2=1, i.e., 2 is divisible by 1 and is 2, and 2 is divisible by 1 and itself, so it is a qualitative curved number.