I am trying to store all prime numbers upto 50 and all non prime numbers above 50 upto 100

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in the code given below,if a number is not prime flag will be set to 1.then store numbers in array using if condition (if(flag==0) store all elements).
then store all non prime numbers above 50 using the condition given below.
if(flag is 1 and array position above 50)
but after 50 position all elements(including prime and non prime)are stored in array.

What I have tried:

C++

#include <stdio.h>

int main() {
    int i,j,k=0,size,a[200],flag;
    printf("enter the size");
    scanf("%d",&size);
    for(i=0;i<size;i++){
 a[i]="i;
" }
="" for(i="0;i<size;i++){
" flag="0;
" for(j="2;j<a[i];j++){
" if(a[i]%j="=0){
" break;
="" if(flag="=0){
" a[k]="a[i];
" k++;
="" &&="" i="">50){
                a[k]=a[i];
                k++;
            }
        }
        for(i=0;i

Posted 9-Aug-22 22:42pm

Amal Ks

Updated 10-Aug-22 9:06am

Patrice T

v2

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OriginalGriff 10-Aug-22 5:15am

We can't read that - it's corrupted because it was "swallowed" by the HTML.
Edit your question, remove the code and re-paste it this time using the "code block" option in the Paste pop-up.

You can use the "Improve question" widget to do that by hovering your mouse over the question body.

Patrice T 10-Aug-22 5:43am

Your code is corrupted, please paste again.
Use Improve question to update your question.

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Richard MacCutchan · Answer 1 · 2022-08-09T23:12:00

Once again you use a fixed size array and then get the actual number from the user. You need to allocate your array space based on the size values chosen by the user; see malloc | Microsoft Docs[^].
You also need a function that checks if a number is a prime or not:

C++

int isPrime(int number)
{
    int result = 1; // assume the number is a prime
    // add the code here to check if it is
    // setting result = 0 if it is not prime

    return result;
}

You can then setup a loop to go through the numbers from 1 to 50 looking for primes, and 50 to 100 looking for non-primes.

OriginalGriff · Answer 2 · 2022-08-09T23:16:00

Compiling does not mean your code is right! :laugh:
Think of the development process as writing an email: compiling successfully means that you wrote the email in the right language - English, rather than German for example - not that the email contained the message you wanted to send.

So now you enter the second stage of development (in reality it's the fourth or fifth, but you'll come to the earlier stages later): Testing and Debugging.

Start by looking at what it does do, and how that differs from what you wanted. This is important, because it give you information as to why it's doing it. For example, if a program is intended to let the user enter a number and it doubles it and prints the answer, then if the input / output was like this:

Input   Expected output    Actual output
  1            2                 1
  2            4                 4
  3            6                 9
  4            8                16

Then it's fairly obvious that the problem is with the bit which doubles it - it's not adding itself to itself, or multiplying it by 2, it's multiplying it by itself and returning the square of the input.
So with that, you can look at the code and it's obvious that it's somewhere here:

C

int Double(int value)
   {
   return value * value;
   }

Once you have an idea what might be going wrong, start using the debugger to find out why. Put a breakpoint on the first line of the method, and run your app. When it reaches the breakpoint, the debugger will stop, and hand control over to you. You can now run your code line-by-line (called "single stepping") and look at (or even change) variable contents as necessary (heck, you can even change the code and try again if you need to).
Think about what each line in the code should do before you execute it, and compare that to what it actually did when you use the "Step over" button to execute each line in turn. Did it do what you expect? If so, move on to the next line.
If not, why not? How does it differ?
Hopefully, that should help you locate which part of that code has a problem, and what the problem is.
This is a skill, and it's one which is well worth developing as it helps you in the real world as well as in development. And like all skills, it only improves by use!

Patrice T · Answer 3 · 2022-08-10T09:06:00

Quote:
but after 50 position all elements(including prime and non prime)are stored in array.

Without complete code, it is difficult to tell where it goes wrong.

advice: It is a bad idea to do monolithic code (a single piece of code that does everything).
When writing code for a task, if you identify a well defined sub-task, it is good practice to write a function that solve the sub-task.
You need to check is an integer is a prime number or not, this is a good example as adviced in solution 1.
It make things easier when it comes to testing/debugging your code.
-----
Your code do not behave the way you expect, or you don't understand why !

There is an almost universal solution: Run your code on debugger step by step, inspect variables.
The debugger is here to show you what your code is doing and your task is to compare with what it should do.
There is no magic in the debugger, it don't know what your code is supposed to do, it don't find bugs, it just help you to by showing you what is going on. When the code don't do what is expected, you are close to a bug.
To see what your code is doing: Just set a breakpoint and see your code performing, the debugger allow you to execute lines 1 by 1 and to inspect variables as it execute.

Debugger - Wikipedia, the free encyclopedia[^]

Mastering Debugging in Visual Studio 2010 - A Beginner's Guide[^]
Basic Debugging with Visual Studio 2010 - YouTube[^]

1.11 — Debugging your program (stepping and breakpoints) | Learn C++[^]

The debugger is here to only show you what your code is doing and your task is to compare with what it should do.

I am trying to store all prime numbers upto 50 and all non prime numbers above 50 upto 100

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