Counting the number of times an int appears in a file - c++

Question

I'm making a simple program that reads in a file and a value from a user, then counters how many time that value appears in the file. I've made this so far, it compiles fine, but when you input a number, nothing happens from there. I'm stumped. Sorry if this is very basic but I can't get past this.
This is what I have so far.
#include <stdlib.h>
#include <iostream>
#include <fstream>
using namespace std;
int hold,searchnumber, counter=0;
int main()
{
cout << "This program reads the contents of a file to discover if a number you enter exists in it, and how many times. \n";
cout << "What number would you like to search for? \n";
cout << "Number : ";
cin >> searchnumber;
ifstream infile("problem2.txt");
if(!infile)
{
cout << "Can't open file problem2.txt";
exit(EXIT_FAILURE);
}
int sum=0,number;
infile >> number;
while (!infile.eof())
{
if (number == searchnumber);
counter = counter += 1;
}
{
cout << "The number " <<searchnumber << " appears in the file " << counter <<" times! \n";
cin >> hold;
}
infile.close();
}

Answer 1

This section contains two problems:
infile >> number;
while (!infile.eof())
{
if (number == searchnumber);
counter = counter += 1;
}
The while condition is either true or false, and if it's true, it stays so forever, and it's likely why "nothing happens". There is NOTHING in the loop that changes the state of infile.
Combine the first two lines to:
while (infile >> number)
Then you at least run through the file.
Now, this:
if (number == searchnumber);
counter = counter += 1;
Since there is a semicolon after the if-statement, you are basically saying "if it's the right number, do nothing" followed by updating the counter no matter whether you found the number or not. Remove the semicolon.
As usual, writing too much and too slowly.

Answer 2

You have an infinite loop at this line:
while (!infile.eof())
{
if (number == searchnumber);
counter = counter += 1;
}
You open the file and read in the lines above it, but this loop just continues until you hit eof, but since you didn't read anything else in, as long as it wasn't eof when you entered the loop it will never exit.

Answer 3

1.
if (number == searchnumber);
counter = counter += 1;
should be
if (number == searchnumber)
counter = counter += 1;
2.
sum is unused.

Answer 4

infile >> number;
while (!infile.eof())
{
if (number == searchnumber);
counter = counter += 1;
}
should be
while (infile >> number)
{
if (number == searchnumber)
counter += 1;
}
You need to read a number from the file each time before you compare. not simply do nothing in the file reading while loop.
BTW: you sum variable seems not used, remove it.