Program crashes at printing string vector - c++

Question

I'm making a program that write and read "reminders", and i when i'll print a string vector with the "reminders" it crashes and i don't know why this happens, it can compile, but it crashes at running, thanks for anyone that tried to help. Here's the code:
vector<string> v = ReadFile();
for(vector<string>::iterator i = v.begin();i != end();i++) {
cout << *i << '\n' << endl;
}
Another "version" of the code, that crashes too:
vector<string> v = ReadFile();
for(int i = 0;i < v.size();i++) {
cout << v[i] << '\n' << endl;
}
Sorry if exits another thread with the same problem.
PS: I'm using MinGW as compiler
Complete code here:
#include <iostream> // Basic IO
#include <fstream> // File IO
#include <stdlib.h> // free()
#include <vector> // For using vectors
#include <string> // For strings
#include <dirent.h> // Read files from folders
#include <windows.h> // GetCurrentDirectory()
void WriteFile(string desc) {
ofstream write(desc.c_str());
write << "Created on: " << __DATE__ << " " << __TIME__ << "\n";
write.close();
printf("\nReminder saved with success");
}
vector<string> ReadFile () {
vector<string> reminders;
DIR *dir;
struct dirent *ent;
LPSTR buffer;
GetCurrentDirectory(MAX_PATH, buffer);
if((dir = opendir(buffer)) != NULL) {
while((ent = readdir(dir)) != NULL) {
reminders.push_back(ent->d_name);
}
closedir(dir);
free(dir);
free(ent);
free(buffer);
} else {
printf("\nError at reading folder or empty folder");
}
return reminders;
}
int main() {
vector<string> v = ReadFile();
for(int i = 0;i < v.size();++i) {
cout << v[i] << '\n' << endl;
}
return 0;
}

Answer 1

This is a problem:
LPSTR buffer;
GetCurrentDirectory(MAX_PATH, buffer);
LPSTR is a typedef for char *, or something similar. However, the GetCurrentDirectory function expects to be passed a buffer that is already allocated. Change to:
char buffer[MAX_PATH+1]; // or TCHAR
GetCurrentDirectory(sizeof buffer, buffer);
Also, you should not call free(buffer) because you did not malloc it.
I believe free(ent); and free(dir); are both errors too, as those functions return pointers into memory which is managed by the runtime library. In general, only call free on things that you malloc'd, or the function's documentation tells you that you need to free.