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Array problem

Posted on 2006-07-18
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Last Modified: 2008-02-01
I am trying to write a function that displays the index of the highest value in the array

The teach gave us  main function and we are just supposed to write the function that finds the index for the highest number

here is the code

#include <iostream>
#include <iomanip>
using namespace std;

//====================================================================
// put your function prototype here
//====================================================================

double FindIndexHighest (double p[], int size);


int main()
{//DO NOT CHANGE ANYTHING IN THE MAIN()
    double x[] = { 11.11, 66.66, 88.88, 33.33, 55.55 };
    double y[] = { 9, 6, 5, 8, 3, 4, 7, 4, 6, 3, 8, 5, 7, 2 };
    double z[] = { 123, 400, 765, 102, 345, 678, 234, 789 };

    cout << fixed <<showpoint << setprecision(2);

    int index = FindIndexHighest (x, sizeof (x) / sizeof (x[0]));
    cout << "Array x:  element index = " << index
         << "  element contents = " << x[index] << '\n';
    index = FindIndexHighest (y, sizeof (y) / sizeof (y[0]));
    cout << "Array y:  element index = " << index
         << "  element contents = " << y[index] << '\n';
    /*cout << "Array z:  element index = "
         << FindIndexHighest (z, sizeof (z) / sizeof (z[0]))
         << "  element contents = "
             << z[FindIndexHighest (z, sizeof (z) / sizeof (z[0])) ] << '\n';*/
    return 0;
}

//====================================================================
// put your function definition here.
//====================================================================

double FindIndexHighest (double p[], int size){
      double highest = 0;
      int index;
      for(double i=0; i<size; i++){
            if (p[i]>highest){
                  highest = p[i];
                  index = i;
            }
      }
      return index;
}


when I try to run this I get the erro message
 error C2108: subscript is not of integral type
in referance to my if statement in my occurances function definition.
i think the program show work otherwise but I have no idea what this error message means.
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Question by:vlahomt
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6 Comments
 

Author Comment

by:vlahomt
ID: 17133818
I commented out the array z section of main because I was getting the same erro message there when my code was not correct now that I think my function should work i just need know what that error message means so i can fix the problem which should probally fix the problem in the array z cout statments.
0
 
LVL 14

Expert Comment

by:wayside
ID: 17134053
   for(double i=0; i<size; i++){
          if (p[i]>highest){   <---------here is your problem
               highest = p[i];
               index = i;
 

array indices must be ints, you declared i as a double:

    for(int i=0; i<size; i++){   <----- change to int
          if (p[i]>highest){
               highest = p[i];
               index = i;
 
etc.
0
 
LVL 14

Expert Comment

by:wayside
ID: 17134076
The reason is, a double as an index makes no sense. What would

p[1.543276]

mean, if it could be a double?

So the compiler helpfully flags the error for you.



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Author Comment

by:vlahomt
ID: 17134263
that fixes the function but I get the same error message if I un comment the cout statement reffering to the array z
0
 
LVL 15

Accepted Solution

by:
efn earned 1200 total points
ID: 17134340
The reason is the same.  FindIndexHighest returns a double and the output statement uses it as a subscript.
0
 
LVL 15

Expert Comment

by:efn
ID: 17135346
Thanks, but with all due respect, I think wayside deserves most or all of the points here.  If you would like to change your decision, you can post a request in the Community Support topic area to get a moderator to undo your acceptance.
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