for loops - noob question

This is a discussion on for loops - noob question within the C Programming forums, part of the General Programming Boards category; Could any help me through the flow of this loop? I understand the syntax, but I am trying to figure ...

  1. #1
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    for loops - noob question

    Could any help me through the flow of this loop? I understand the syntax, but I am trying to figure out the flow of the for loop and why it prints how it prints.

    The output starts as:
    0
    1
    1
    2
    3
    5
    ...

    why in the loop does it print zero, then two sets of 1's. When I try and follow the loop, I figure it to start 0 for the initial then 1,2...

    Thanks

    Code:
    #include <stdio.h>;
    
    int main (void)
    {
    	
    
    int firstval = 0;
    int secondval = 1;
    int tempvalue, count = 15;
    
    for (count = 1; count <= 15; count++)
    {
    	tempvalue = firstval + secondval;
    
    	printf("%d\n", firstval);
    	firstval = secondval;
    	secondval = tempvalue;	
    
    
    	}
    
    
    	getchar();
    	return 0;
    
    }

  2. #2
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    Just follow the values of your variables... write them down for several times around the loop... step by step... you'll see what it's doing.

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    I see, I got it. thanks.

  4. #4
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    Quote Originally Posted by teelnaw View Post
    I see, I got it. thanks.
    You're welcome.

    One of the most important things for a programmer to learn is troubleshooting... how to analyse a situtation that's gone wrong.

  5. #5
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    FYI :

    Another part of programming is recognizing common sequences which show up in toy homework problems (and eventually toy interview questions) : Fibonacci number - Wikipedia, the free encyclopedia.

    This also shows up if you do a google search for 0 1 1 2 3 5. That's useful for finding hints about other sequences (but in my experience more complex sequences just get matched up to phone numbers so it's not always going to help).

  6. #6
    Third Eye Babkockdood's Avatar
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    Don't put a semicolon after a preprocessor.

  7. #7
    Registered User claudiu's Avatar
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    Quote Originally Posted by Babkockdood View Post
    Don't put a semicolon after a preprocessor.
    Wow, eyes of the eagle . Well done sir!
    1. Get rid of gets(). Never ever ever use it again. Replace it with fgets() and use that instead.
    2. Get rid of void main and replace it with int main(void) and return 0 at the end of the function.
    3. Get rid of conio.h and other antiquated DOS crap headers.
    4. Don't cast the return value of malloc, even if you always always always make sure that stdlib.h is included.

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