Trying to use qsort to sort a cstring - c++

Question

I am trying to sort two cstrings, and I'm running into trouble while using qsort to complete this task. I believe my problems are that I'm not sure what to put as the parameters for compare, if my compare function is correct, or if it is even necessary for me to write my own compare function at all.
#include <algorithm>
#include <iterator>
#include <iostream>
#include <cstring>
#include <string>
using namespace std;
bool anagram(const char *s1, const char *s2);
int main() {
string sWord1, sWord2;
char cWord1[10], cWord2[10];
char *cPtr1 = cWord1;
char *cPtr2 = cWord2;
cout << "Enter Word 1: ";
cin.getline(cWord1, 10);
cout <<"\nEnter Word 2: ";
cin.getline(cWord2, 10);
anagram(cPtr1, cPtr2);
return 0;
}
bool anagram(const char *s1, const char *s2) {
char w1[10];
char w2[10];
for (int i = 0; i < 10; i++) {
w1[i] = s1[i];
w2[i] = s2[i];
}
sort(w1.begin(), w1.end()); //DOES NOT WORK
sort(begin(w1), end(w1)); //DOES NOT WORK - Says begin is not in std
}

Answer 1

The correct way to sort an array of chars in C++ is to use std::sort:
#include <algorithm>
#include <iterator>
bool anagram(const char *s1, const char *s2) {
// ...
std::sort(std::begin(w1), std::end(w1));
// If you can't use C++11, then use
// std::sort(w1, w1 + 10);
// ...
}
If you have to use qsort for some weird reason, it expects a function pointer taking two const void * parameters that point to the elements to be compared:
int compare(const void * e1, const void *e2){
char c1 = *static_cast<const char *>(e1), c2 = *static_cast<const char *>(e2);
return c1 - c2; // <0 if c1 < c2, etc.
}
qsort(w1, 10, sizeof(char), compare);
This is slow, error prone, and causes undefined behavior for nontrival types, and is not recommended.

Answer 2

This is your code as you were trying to write it. But as has been pointed out, qsort is not the preferred approach.
#include <cstdlib>
#include <cstring>
#include <iostream>
int compare(const void* c1, const void* c2) {
const char& cc1 = *static_cast<const char*>(c1);
const char& cc2 = *static_cast<const char*>(c2);
return cc1 - cc2; }
bool anagram(const char* s1, const char* s2) {
char w1[10];
char w2[10];
for (int i = 0; i < 10; i++) {
w1[i] = s1[i];
w2[i] = s2[i]; }
qsort(w1, 10, sizeof(char), compare);
qsort(w2, 10, sizeof(char), compare);
return 0 == strncmp(w1, w2, 10); }
int main(int, char* []) {
std::cout << anagram("abcdefghij", "bcdaghefji") << std::endl;
std::cout << anagram("abcdefghij", "xxxxxxxxxx") << std::endl;
return 0; }