recursive find of the smallest member..

This is a discussion on recursive find of the smallest member.. within the C Programming forums, part of the General Programming Boards category; i wrote a function that finds recursively the smallest member in an int array and it says that "min is ...

  1. #1
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    recursive find of the smallest member..

    i wrote a function that finds recursively the smallest member in an int array
    and it says that "min is being used without being defined"

    i cant put a value into min
    i need to get it from the process.


    ??
    Code:
    #include <stdio.h>
    int recFindMin (int array[] ,int index);
    
    int main()
    {
    	int t,array[3];
    	
    	 array[0]=2;
    	 array[1]=1;
    	 array[2]=3;
        t=recFindMin(array,2);
    	printf("%d\n",t);
    
       return 0;
    }
    
    
    
    int recFindMin (int array[] ,int index)
    {
    	int min,local;
        if (index==0)
    	{
           return array[index];
    	}
        
        local=recFindMin (array ,index-1);
    	if (array[index]>local)
    	{
    	   min=local;
    	}
    	 return min;
    }//end func
    Last edited by transgalactic2; 01-12-2009 at 03:31 PM.

  2. #2
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    And exactly why do you need min at all?

    More importantly, what is min when you have a
    Code:
    array[index]<=local
    --
    Mats
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  3. #3
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    min is the total minimum
    and local is the temporary

  4. #4
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    what is the problem in the function code?

  5. #5
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    Quote Originally Posted by transgalactic2 View Post
    what is the problem in the function code?
    Did you not trace through your function for the case I described: What is the value of min when your second if-statement is false?

    --
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    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

  6. #6
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    in the case you described
    nothing changes
    min changes only if there is a smaller number then it.
    i added an empty else case.

    i traced it
    but from the start my array has only one cell of value 2
    ??
    Code:
    #include <stdio.h>
    int recFindMin (int array[] ,int index);
    
    int main()
    {
    	int t,array[3];
    	
    	 array[0]=2;
    	 array[1]=1;
    	 array[2]=3;
        t=recFindMin(array,2);
    	printf("%d\n",t);
    
       return 0;
    }
    
    
    
    int recFindMin (int array[] ,int index)
    {
    	int min,local;
        if (index==0)
    	{
           return array[index];
    	}
        
        local=recFindMin (array ,index-1);
    	if (array[index]>local)
    	{
    	   min=local;
    	}
    	else
    	{
    	}
    	 return min;
    }//end func

  7. #7
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    So, what value does min actually have in that situation? To put it another way, what value does a variable have that hasn't been set?

    --
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    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

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    i think iteratively
    min doesnt change
    its stays with the same value from the previous call

  9. #9
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    Quote Originally Posted by transgalactic2
    i think iteratively
    Start thinking recursively then

    For example, suppose there is a "magic function" that gives you the minimum value in the rest of the array. To implement recFindMin to find the minimum, all you need to do is compare the current value with the value returned from that "magic function", returning the smaller one. Easy, isn't it?

    Oh, and did I mention that the "magic function" is, coincidentally, recFindMin?
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    thanks i solved it

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    thats what i am doing i am comparing the index member with the rest of the members behind it
    ??

  12. #12
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    Quote Originally Posted by transgalactic2 View Post
    thats what i am doing i am comparing the index member with the rest of the members behind it
    ??
    Looks like you posted on the wrong thread.
    Not everything that can be counted counts, and not everything that counts can be counted
    - Albert Einstein.


    No programming language is perfect. There is not even a single best language; there are only languages well suited or perhaps poorly suited for particular purposes.
    - Herbert Mayer

  13. #13
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    no i am on the correct thread
    i am trying to fix this function

    i have done the compare with the rest part
    but something is missing
    ??
    Code:
    #include <stdio.h>
    int recFindMin (int array[] ,int index);
    
    int main()
    {
    	int t,array[3];
    	
    	 array[0]=2;
    	 array[1]=1;
    	 array[2]=3;
        t=recFindMin(array,2);
    	printf("%d\n",t);
    
       return 0;
    }
    
    
    
    int recFindMin (int array[] ,int index)
    {
    	int min,local;
        if (index==0)
    	{
           return array[index];
    	}
        
        local=recFindMin (array ,index-1);
    	if (array[index]>local)
    	{
    	   min=local;
    	}
    	else
    	{
    	}
    	 return min;
    }//end func

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    how to fix it

  15. #15
    and the hat of copycat stevesmithx's Avatar
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    What is the initial value of local?.
    First try to solve the problem yourself using a debugger and use the forum only as a last resort.
    Not everything that can be counted counts, and not everything that counts can be counted
    - Albert Einstein.


    No programming language is perfect. There is not even a single best language; there are only languages well suited or perhaps poorly suited for particular purposes.
    - Herbert Mayer

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