hello friends.

[vijayshankar]

hello friends, am vijay shankar.. am new to this forum as well as c program. so pls help me out by correcting me. i have written a program for prime, pls do tell me my mistakes.

main()
{
int i,n;
printf("number:");
scanf("%d",&n);
for(i=2;i<n;i++)
{
if(n%i==0)
break;
else continue;
}
if(n==i)
printf("\nits prime");
else
printf("\nnot prime");
getch();
}

[GReaper]

hello friends, am vijay shankar.. am new to this forum as well as c program. so pls help me out by correcting me. i have written a program for prime, pls do tell me my mistakes.

Use code tags first!

[Adak]

Welcome to the forum, Vijay!

Unfortunately, code without code tags around it, looks like something the cat drug in from the street - very hard to study.

In your program, you're missing that second loop or function:

Loop 1. Get the next number to be tested to see if it's prime

Loop 2. In this inner loop, get the next number to be tested to see if it's an even factor into the number from loop 1.

Loop 2 can easily be another function, instead of a nested loop, in your design.

[vijayshankar]

@Adak:


but am getting the ouput correctly..

[vijayshankar]

#include<stdio.h>
#include<conio.h>
void main()
{
int i,n;
printf("enter no:");
scanf("%d",&n);
for(i=2;i<n;i++)
{
if(n%i==0)
break;
else
continue;
}
if(n==i)
printf("\n prime");
else
printf("\n not prime");
getch();
}

[nimitzhunter]

for(i=2;i<n;i++)
{
      if(n%i==0)
          break;
      //// don't need these line. 
      ///////////
      ///else
      ///continue;
     /////////////////
}

but am getting the ouput correctly..

Your program works to test whether a number is primes. It will be slow to use it in the future to generate primes though, just so you know.

[Adak]

OK, I misunderstood. I thought you wanted to find a LOT of primes, instead of testing only one number to see if it's prime.

Code tags look great! :thup:

main() in C, is always int main with a return of zero for a normal run.

No void main(), ever. It may run, but you should be getting a warning from your compiler, even if it's Turbo C.

Subordinate lines of code should be indented 2 to 5 spaces, to let you easily see how the logic is working in your program. With practice, your eye will become good at finding some errors, quite easily if you use that format.

Also, others can much more easily study your code.

As noted above, some of the code is redundant. More clear and concise code is always the way you want to go, with any programming code.

Rube Goldberg's are not anyone's friends, in programming.

[vijayshankar]

Thank you friends.... am just a beginner in C. so pls bear with my silly mistakes and questions...

@nimitzhunter: you mean , the following coding , wright?

else
continue;

so, other than this part, is my coding short or still is it lenghty?

[Adak]

It's fine, otherwise.

[vijayshankar]

If i wanna clear more such doubts, shall i continue it in the same thread or a new one.

[Adak]

New code you have doubts about = new thread.

This code you have doubts about = this thread.