How to return the last element of an array?

This is a discussion on How to return the last element of an array? within the C Programming forums, part of the General Programming Boards category; Hi guys, I'm trying to create a function that will return the last element of an array. I am working ...

  1. #1
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    How to return the last element of an array?

    Hi guys,

    I'm trying to create a function that will return the last element of an array. I am working in ANSI C.

    Code:
    char *top(void) {
        int i;
        /* Check for the last element */
        for(i = 0; stack[i] != '\0'; i++) {
    	
        }
        /* Return the last element of the array */
        return ???;
    }
    I have no idea how to go about checking for the last element of the array.

    Help would be GREATLY appreciated!

    Kind regards,
    BuezaWebDev
    Last edited by BuezaWebDev; 03-25-2005 at 01:50 AM.

  2. #2
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    What is stack declared as? Is it an int, char, etc?

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    Oops, sorry. It's an integer.

    int stack[10];

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    Code:
    int top(void) 
    {
        int i;
        for(i = 0; stack[i] != '\0'; i++)
    	;
    
        return stack[--i];
    }

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    Yay, l0cke!

    Thank you so much! So basically, the loop will keep iterating until the end (once it hits the null character), and then integer i will be set to the last index number?

    I would have never thought of that logic! Thank you!

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    i is set to the last index number + 1, that's why the return is return stack[--i], so it subtracts 1 from i before it returns it.
    Last edited by l0cke; 03-25-2005 at 02:31 AM.

  7. #7
    Registered User hk_mp5kpdw's Avatar
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    What if there are no elements in the array? What if array[0] == '\0' and you then try and return stack[-1]?
    "Owners of dogs will have noticed that, if you provide them with food and water and shelter and affection, they will think you are god. Whereas owners of cats are compelled to realize that, if you provide them with food and water and shelter and affection, they draw the conclusion that they are gods."
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    or u can do this

    Code:
    return stack[strlen(stack)-1];
    s.s.harish

  9. #9
    Registered User hk_mp5kpdw's Avatar
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    Quote Originally Posted by ssharish
    or u can do this


    Code:

    return stack[strlen(stack)-1];


    s.s.harish
    First, let me say that the use of '\0' in an integer array as an end of array indicator is suspect. It makes little sense.

    You would not want to use strlen with an integer array. Disregarding for the moment that the op is using an integer array (pretending that it is a NULL terminated character array), you have the same problem using strlen... what if strlen returns 0? Then you are still returning stack[-1]
    "Owners of dogs will have noticed that, if you provide them with food and water and shelter and affection, they will think you are god. Whereas owners of cats are compelled to realize that, if you provide them with food and water and shelter and affection, they draw the conclusion that they are gods."
    -Christopher Hitchens

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    lol, sorry if it is an interger array please ignore my post

    s.s.harish

  11. #11
    Just Lurking Dave_Sinkula's Avatar
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    Code:
    #include <stdio.h>
    
    int main(void)
    {
       int array[] = {1,2,3,4,5,6,7,8,9};
       int last_element = array [ sizeof array / sizeof *array - 1 ];
       printf("last_element = %d\n", last_element);
       return 0;
    }
    
    /* my output
    last_element = 9
    */
    7. It is easier to write an incorrect program than understand a correct one.
    40. There are two ways to write error-free programs; only the third one works.*

  12. #12
    char main() RoshanX's Avatar
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    From what I can understand, the array might not be filled to the end, and we want to get the last element of the stack. ( assuming you are implementing a integer stack. ).

    A return value of END ( -999) indicates that the stack is empty.

    Code:
    #define END -999
    
    int top(void) 
    {
         int i;
        /* Check for the last element */
    
        for(i = 0; stack[i] != END ; i++) ;
       
     /* Return the last element of the array */
        i--;
        if (i <0 )
             return END;
        else
           return stack[i];
    }

  13. #13
    ATH0 quzah's Avatar
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    If this is a stack, why on earth aren't you storing where the top of it is? Increment it when you push, decrement it when you pop. Any other function call is a waste of time.

    Quzah.
    Hope is the first step on the road to disappointment.

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    In my int main(void), I have variables that store the "top" integer.

  15. #15
    ATH0 quzah's Avatar
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    So why are you wasting time finding the last element instead of directly referencing top?

    Quzah.
    Hope is the first step on the road to disappointment.

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