Nested while loop inside for loop

**Sonny** · 07-31-2011

Originally Posted by beta3designs

I think you still have the duplicated asking for student's ID...
Ok, let's see... If you ask for an ID let's say you enter '1' then you finish entering the marks and it asks you to enter an ID (with the press 0 to exit) and you enter '2' but then it asks again (without the press 0) and you input '3' then you'll be entering the marks for student '3' not your first selection '2'...
You only need to ask once! Not at the start and at the end... you should only ask at the start

EDIT: Bold should be after the validation loop and I didn't notice that you were modifying the values inside of it and maybe my tests didn't affect the values but I can see that's solved now :P

Yeah but look at this, it's a sample from my assignment;
As you can see it asks for the Section code (without 0 to exit) and then asks again with the zero to exit. How do I do that? :s

Enter the Section Code: 0
Invalid value entered. Must be 1 to 4, please re-enter: 1
Enter the Student's ID: 456789
Enter mark#1: 10
Enter mark#2: -20
Invalid grade entered. Must be 0.0 to 20.0, please re-enter: 20
Enter mark#3: 5.5
Enter mark#4: 5
Enter mark#5: 10
000456789's total mark is: 50.5

Enter the Student's ID ['0' to quit]: 123654987
Enter mark#1: 1
Enter mark#2: 2
Enter mark#3: 3
Enter mark#4: 4
Enter mark#5: 5
123654987's total mark is: 15.0

Enter the Student's ID ['0' to quit]: 0
The average for the section is 32.75%

Enter the Section Code [0 to quit]: 5

**Sonny** · 07-31-2011

Originally Posted by beta3designs

I think you still have the duplicated asking for student's ID...
Ok, let's see... If you ask for an ID let's say you enter '1' then you finish entering the marks and it asks you to enter an ID (with the press 0 to exit) and you enter '2' but then it asks again (without the press 0) and you input '3' then you'll be entering the marks for student '3' not your first selection '2'...
You only need to ask once! Not at the start and at the end... you should only ask at the start

EDIT: Bold should be after the validation loop and I didn't notice that you were modifying the values inside of it and maybe my tests didn't affect the values but I can see that's solved now :P

So i'm good right? Even with the two student ID prompts? Is there any way around that?

**~~CommonTater~~** · 07-31-2011

Originally Posted by Sonny

Wait so for a validation loop I don't have to scanf?!

Actually that's the only thing that should be in your loop...

**Sonny** · 07-31-2011

Originally Posted by CommonTater

Code:

do {
  total = 0;
  loop++;
  printf("Enter the Student's ID: ");
  scanf("%d", &studID);

  for (m = 1; m < 6; m++)
  {
    printf("Enter Mark #%d: ", m);
    scanf("%f", &mark);
    while (mark > 20 || mark < 0)
    {
      printf("Invalid grade entered. Must be 0.0 to 20.0, please re-enter: ");
      scanf("%f", &mark);
      total = total + mark;                          <---- delete this line
      average = (store / (loop * 100)) * 100;      <---- and this one
    }
    store = store + mark;
    total = total + mark;
    average = (store / (loop * 100)) * 100;
  }

  printf("%d's total mark is: %.2f\n", studID, total);
  printf("Enter the Student's ID ['0' to quit]: ");
  scanf("%d", &doAgain);
} while (doAgain);

printf("The average for the section is: %.2f%\n", average);
}

What you need to do is stop and think like the program... BE the program... "Do I want to do this in the middle of an error condition?"....

I AM the program. lol I just posted my updated code on the last page I fixed it.

**~~CommonTater~~** · 07-31-2011

Sonny... same advice as yesterday... think, plan, do...

C does stuff in the exact order you tell it... so your question is "Do I want to do this now?"...

**AndrewHunter** · 07-31-2011

Originally Posted by Sonny

Code:

do {
    total = 0;
    loop++;
    printf("Enter the Student's ID: ");
    scanf("%d", &studID);

    for (m = 1; m < 6; m++)
    {
      printf("Enter Mark #%d: ", m);
      scanf("%f", &mark);
      while (mark > 20 || mark < 0)
      {
        printf("Invalid grade entered. Must be 0.0 to 20.0, please re-enter: ");
        scanf("%f", &mark);
        
      }
      store = store + mark;
      total = total + mark;
      average = (store / (loop * 100)) * 100;
    }

    printf("%d's total mark is: %.2f\n", studID, total);
    printf("Enter the Student's ID ['0' to quit]: ");
    scanf("%d", &studID);
  } while (studID != 0);

printf("Enter the Section Code ['0' to quit]: ");
scanf("%d", &sCode);
} while (sCode != 0);
printf("The average for the section is: %.2f%\n", average);

}

The parts in red are where you ask the user for student id. So if you didn't want the first part to repeat in your do-while loop, where would you move it to?

**quzah** · 07-31-2011

Originally Posted by CommonTater

Sonny... same advice as yesterday... think, plan, do...

C does stuff in the exact order you tell it... so your question is "Do I want to do this now?"...

Sometimes the order doesn't work out like that, but it really should. A number of years ago I wrote something drunk, and couldn't figure out what it was doing the next day when I was sober.

But it worked.

Think. Plan. Do-while( sober );

Quzah.

**Sonny** · 07-31-2011

Originally Posted by AndrewHunter

The parts in red are where you ask the user for student id. So if you didn't want the first part to repeat in your do-while loop, where would you move it to?

Before the do while loop?

**AndrewHunter** · 07-31-2011

Hmm....why don't you try that out and see what you get.

**Sonny** · 07-31-2011

Originally Posted by AndrewHunter

Hmm....why don't you try that out and see what you get.

I did and it works perfectly. How'd you decipher it so fast?

**~~CommonTater~~** · 07-31-2011

Originally Posted by Sonny

I did and it works perfectly. How'd you decipher it so fast?

Quzah and I phoned him and told him what to post in a conference call

**AndrewHunter** · 07-31-2011

Just experience. No magic there, except for quzah's drunk coding that is.

Keep working on the techniques everyone has been telling you and you will be able to do it as well.

**Sonny** · 07-31-2011

Originally Posted by CommonTater

Quzah and I phoned him and told him what to post in a conference call

Very efficient. :P haha thanks a lot for the help guys. Hopefully after a little more experience I can help future noobs like you're helping me.

**AndrewHunter** · 07-31-2011

Originally Posted by CommonTater

Quzah and I phoned him and told him what to post in a conference call

D**n, now my secret is out! ...LOL

EDIT: BTW Tater, I like your new tag line.

**Sonny** · 07-31-2011

Originally Posted by AndrewHunter

Just experience. No magic there, except for quzah's drunk coding that is.

Keep working on the techniques everyone has been telling you and you will be able to do it as well.

lmaoo! I can't even properly take a leak when i'm drunk...I will bud thank you.

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