``````#include<stdio.h>

int main()
{

int pcheck=1,i;
int k=1000

for(i=2;i<k;i++)
{

if((k%i)== 0)
{
pcheck=0;

break;
}

}

if(pcheck)
{
printf("%d is a prime .\n",k);

}
else
{
printf("%d is not a prime.\n",k);

}

return 0;
}
``````

this code works to check any number i that write in k but when i put a do while loop.stating that do while should loop while k!=0 then i k-- so that can check if all the number less than 1000 are prime. it prints all not prime..please guys help me

If you're having problems with a do loop, you need to post up code that includes the do loop. ;)

Using CODE TAGS! <of course> Putting your code right between code tags, lets your code stay looking like code, and not like a dog's breakfast.

Your code is not formatted.

Wrong
int k=100;

Correct
int k = 100

``````#include<stdio.h>

int main()
{

int pcheck = 1,i;
int k = 1000

for(i = 2;i < k;i++)
{

if((k % i) == 0)
{
pcheck = 0;

break;
}
}

if(pcheck)
{
printf("%d is a prime .\n",k);
}
else
{
printf("%d is not a prime.\n",k);
}

return 0;
}``````

Indentation is pretty important too, especially when you have a problem with looping

``````#include<stdio.h>

int main()
{
int pcheck = 1,i;
int k = 1000

for(i = 2;i < k;i++)
{
if((k % i) == 0)
{
pcheck = 0;
break;
}
}

if(pcheck)
{
printf("%d is a prime .\n",k);
}
else
{
printf("%d is not a prime.\n",k);
}

return 0;
}``````
``````#include<stdio.h>
#include<conio.h>
void main()
{
int flag=0;
int a=11,i,temp,temp=a;
for(i=1;i<=temp;i++)
{
if((a%i)==0)
{flag++;
}
}
if(flag==2)
{
printf("prime");
}
``````