How to use sort and compare both functions to sort a char array in c++?

Question

#include <iostream>
#include <algorithm>
using namespace std;
// define compare function to compare between char i and j
 _____________________{       // Line-1: Write proper function header

      _____________________;   // Line-2: Write correct function body

 }
int main() {
    char data[5];

    for (int i = 0; i < 5; i++)
        cin >> data[i];

    sort(data, data + 5, compare);

    for (int i = 0; i < 5; i++)
        cout << data[i] << " ";

    return 0;
}

In the above code what will be in LINE1 and LINE2 ,

sort(data, data + 5, compare);

in this why its taking the compare function, and I checked or compare function in c++ it takes two strings as arguments but here its not passing any arguments

`compare` will be invoked from `sort` implementation with appropriate arguments. — user7860670, Aug 13 '19 at 15:45
Looks like LINE1 and LINE2 were assigned to you to complete, not us. related/dupe: https://stackoverflow.com/questions/1380463/sorting-a-vector-of-custom-objects — NathanOliver, Aug 13 '19 at 15:46
That's obviously a homework / test / interview question. Please show yor own efforts first, and whhere you got stuck with this. — πάντα ῥεῖ, Aug 13 '19 at 15:47
Check your favorite reference for "function pointers" or "passing pointers to functions". — Thomas Matthews, Aug 13 '19 at 15:52

score 3 · Accepted Answer · answered Aug 13 '19 at 15:56

3

The sort function gathers it's objects from the range that you pass, i.e. the first two parameters.

For example, it could take data[0] and data[1] as two objects.

The next step would be to compare the two items. Usually, sorting requires comparing items.

The sort function calls compare with data[0] and data[1] to determine the ordering.

In summary, the sort function may call the comparison function to determine the ordering of the objects within the range you specified.

answered Aug 13 '19 at 15:56

Thomas Matthews

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I tried this, but its showing error, can't figure out why – Aug 13 '19 at 16:05
`bool compare(char data[i], char data[i+1])` – Aug 13 '19 at 16:11
`retun (data[i]>data[i+1]);` – Aug 13 '19 at 16:11
`bool compare(char a, char b) { return a > b; }` or use `return a < b;`. – Thomas Matthews Aug 13 '19 at 16:13

How to use sort and compare both functions to sort a char array in c++?

1 Answers1