C++ finding index of value in array

Question

I have recently started working with the Arduino (which is C++).

When I run the below function (along with other code):

int index(int val,int list) {
      int i;
      for (i = 0; i < 8; i++) {
        if (val == list[i]) {
          return i;
        }
      return null;
    }
   }

I get an error on the line if (val == list[i]) {:

invalid types 'int[int]' for array subscript

I have two questions: Why is the error happening, and is there some better way to get the index of a value in an array without using complex syntaxes?

list is an int, not an array. You can't index it like that. — mediocrevegetable1
– mediocrevegetable1, Commented Jun 26, 2021 at 15:07
You're list parameter is just a simple int. You'd want to update this to be an int* or maybe even an std::vector reference. You'd then just need to update the calling code to work with this. — Will Moffat
– Will Moffat, Commented Jun 26, 2021 at 15:08

Papai from BEKOAIL · Accepted Answer · 2021-07-02 11:40:22Z

3

you should accept as an array instead of single-variable in function:

int index(int val, int *list) {
  int i;
  for (i = 0; i < 8; i++) {
    if (val == list[i]) {
      return i;
    }    
  }

  /* if no match found */
    return -1;
}

Note: you need to return an integer value instead of null, since the return type of the function is int.

edited Jul 2, 2021 at 11:40

answered Jun 26, 2021 at 15:08

Papai from BEKOAIL

1,5391 gold badge13 silver badges18 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

kingsjester · Accepted Answer · 2023-09-21 14:42:46Z

0

Same answer as the accepted one, but with more recent c++ features :

int index(int val, int *list) 
{
    auto it = std::find(list, list + 8, val);
    if( it == list + 8 )
    {
        return -1; // if no match found
    }
    else
    {
        return distance(list, it);
    }
}

Note: you need to return an integer value instead of null, since the return type of the function is int.

answered Sep 21, 2023 at 14:42

kingsjester

4421 gold badge6 silver badges18 bronze badges

Collectives™ on Stack Overflow

C++ finding index of value in array

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related