First Lecture Confusion

[AsHiR BuTt]

Asalam o ALikum!

yrrrrrr agar kisi ny first lecture lia tu us ma jo refactor kia program ko us ma error a raha koi help kr dy. code nichy dy raha hon es ma error dy raha k [Error] 'f' was not declared in this scope:

ya kon sy scope ka error ha koi help kr dy plzzzz

#include <iostream>
#include <fstream>
#include<conio.h>
int onkeypress()
{
char b = std::cin.get();
std::cout b std::endl;
return b == 'x';
}
int onfilechanged()
{
char a = f.get();
std::cout a std::endl;
return a == 'x';
}
int main()
{
char a = '-', b;
do {
if (kbhit()) {
if (onkeypress())
return 0;
}
std::ifstream f("test.txt", std::ifstream::in);
if (f.good() && a != f.peek()) {
if (onfilechanged())
return 0;
}
f.close();
} while (true);
return 0;
}