Logical error from std string find method and count algorithm - c++

Question

When I was about to solve a project euler problem in C++, this was some of the experimentation code I made. It produced a quite unexpected result, so I solved it in an other programming language. But I really want to understand why this error occured. The part one of the code executes as expected, it does not print AAAA. But in part two, the logically equivalent code (the if statement) executes when the variable s is AAAA. And I have no idea why. I hope I made my problem clear, every answer given is highly appreciated! Thanks :)
Note: i'm using count from <algorithm>
#include <iostream>
#include <algorithm>
using namespace std;
int main (int argc, char** argv) {
string alt = "LOA";
// CODE PART 1
string stringToFind = "AAA";
string df = "AAAA";
if (df.find(stringToFind) == string::npos && count(df.begin(), df.end(), 'L') <= 1) {
cout << df; // this does not print AAAA
}
/* CODE PART 2:
this was an attempt to print out every four length string combination
of the characters L, O, A where strings with three A's in a row and
more than one L were excluded.
*/
for (size_t i = 0; i < 3; i++) {
char c1 = alt[i];
for (size_t iT = 0; iT < 3; iT++) {
char c2 = alt[iT];
for (size_t itr = 0; itr < 3; itr++) {
char c3 = alt[itr];
for (size_t itrI = 0; itrI < 3; itrI++) {
char c4 = alt[itrI];
string s = string(&c1)+string(&c2)+string(&c3)+string(&c4);
if (s.find(stringToFind) == string::npos && count(s.begin(), s.end(), 'L') <= 1) {
cout << s << endl; // this however, does print out AAAA
}
}
}
}
}
return 0;
}

Answer 1

You have written
string s = string(&c1)+string(&c2)+string(&c3)+string(&c4);
You meant:
string s = string(1,c1)+string(1,c2)+string(1,c3)+string(1,c4);
or
string s = string(&c1,1)+string(&c2,1)+string(&c3,1)+string(&c4,1);
In your code, you have invoked the string constructor which takes a pointer to a nul-terminated array of char, but you given it a pointer to a single char. That's going to invoke all sorts of undefined behaviour.
Either invoke the constructor that takes a a counter + a single char or, the one which takes a pointer and a count, and you can tell it there is exactly one character at that address.
Edit There is no constructor which takes a single char. You have to give it a count + char. Which means it's not so pretty.