PHP, Reading Text File For String - php

Question

i am trying to read a text file and find out if there is a string in there. i have tried many different ways. this is what i have so far,
$file = "./userpass.txt";
$loginuser = $_POST[loginuser];
$loginpass = $_POST[loginpass];
$fileauth = file_get_contents($file);
if (strpos($file,$loginuser) !== false and strpos($file,$loginpass) !== false) {
echo 'Incorrect Password';
} else {
echo 'Hello The Master';
}

Answer 1

change
$loginuser = $_POST[loginuser];
$loginpass = $_POST[loginpass];
to
$loginuser = $_POST['loginuser'];
$loginpass = $_POST['loginpass'];
and this code reads file contents
$fileName = "newfile_testing.txt";
$file_handle= fopen($fileName , "r");
$theData = fread($file_handle, filesize($fileName));
print_r($theData);

Answer 2

You have syntax error. Fix it first. $_POST[loginuser]; should be $_POST['loginuser']; and $_POST['loginpass'];. In strpos() $file should be $fileauth.
$file = "./userpass.txt";
$loginuser = $_POST['loginuser'];
$loginpass = $_POST['loginpass'];
$fileauth = file_get_contents($file);
if (strpos($fileauth,$loginuser) !== false and strpos($fileauth,$loginpass) !== false) {
echo 'Incorrect Password';
}else {
echo 'Hello The Master';
}

Answer 3

Your main problem is that you are trying to find the user/password combination in the filename of that particular file ($file) instead searching against it's contents ($fileauth):
if (strpos($fileauth,$loginuser) !== false and strpos($fileauth,$loginpass) !== false) {
As noted by #Please Wait in his answer (nice catch), you also need to reference the $_POST indexes as a string, so
$loginuser = $_POST[loginuser];
$loginpass = $_POST[loginpass];
should be :
$loginuser = $_POST['loginuser'];
$loginpass = $_POST['loginpass'];