Subtraction between data in file1 and file2 using PHP - php

Question

Suppose that I have 2 files:
File1.txt
10;30;15;40;12;14;15
23;32;10;50;12;54;60
File2.txt
2;4;5;6;7;8;9
3;6;7;8;9;0;7
I want to subtration between these 2 files. Ex 10 - 2........
PHP code:
$file1 = 'File1.txt';
$file2 = 'File2.txt';
if(file_exists($file1)){
$files = fopen($file1,'r');
while(!feof($files)){
$data = explode(";",fgets($files));
if($title ==""){
$title = $data[0];
}
if(!empty($data[3])){
$cate = $data[3];
$filepmta = fopen($file2,'r');
while(!feof($filepmta)){
$hourData = explode(";",fgets($filepmta));
if(!empty($hourData[3])){
if($title ==""){
$title = $hourData[0];
}
if(!empty($btnHour)){
echo $percentRed = ((int)$data[2] - (int)$hourData[2]);
//it loads page so long time so I don know what's error.
}
}
}
It loads the page is so long time.I don know how to fix this,Anyone know help me please,thanks.

Answer 1

I would recommend just simply opening both files and storing the contents of the file into memory. IE Create 2 simple loops (not nested) which iterates through both files respectively and saves the content to an array.
Then make one more loop after the first two. Iterate through the third loop based on the array size of the first two. (I'm assuming you can assume they are both the same size, but it will be a good idea to add checks to make sure loop 1 and loop 2 produce the same size/length arrays.
Within the 3rd loop iterate through both previously two generated arrays with the same index.
Pseudo Code // even tho I said I'd do pseudo code, I ended up doing it all. :-/
$file_values1 = $file_values2 = $answers = array();
while(!feof($file1)) $file_values1[] = explode(';', fgets($file)); // loop 1
while(!feof($file2)) $file_values2[] = explode(';', fgets($file)); // loop 2
foreach($file_values1 as $key1 => $sub_array) { // loop 3
foreach($sub_array as $key2 => $value) // loop 4; hehe, oh wellz
{
$answers[] = $file_values1[$key1][$key2] = $file_values2[$key1][$key2]
}
}
Basically, the nested loop 4, meh. There ARE faster answers. The 3rd loop can be improved upon, it's O(N^2). I'll leave that for you to optimize. No free lunches. :-)

Answer 2

fgets() doesn't move the file pointer after the last line, so you're staying on the last line, feof() still returns false and you're trapped in an infinite loop.
The common way of doing what you want is:
while (($line = fgets($handle)) !== false) {
echo $line;
}
Have a look at the code example in fgets() documentation, it's quite exhaustive.

Answer 3

You're making this way more complicated than it has to be.
Open your files and read them both in with file(), which will give you an array of lines in each file.
Iterate over both line arrays simultaneously with a MultipleIterator.
Convert each lines' contents to arrays with str_getcsv() and an array_map() trick.
Iterate over each line values with another MultipleIterator.
Compute the subtraction and print it.
That's all it takes! I've implemented the above algorithm below.
$file1 = 'File1.txt';
$file2 = 'File2.txt';
$file1 = file( $file1);
$file2 = file( $file2);
$iter = new MultipleIterator;
$iter->attachIterator( new ArrayIterator( $file1));
$iter->attachIterator( new ArrayIterator( $file2));
foreach( $iter as $element) {
list( $line1, $line2) = array_map( 'str_getcsv', $element, array( ';', ';'));
$val_iter = new MultipleIterator;
$val_iter->attachIterator( new ArrayIterator( $line1));
$val_iter->attachIterator( new ArrayIterator( $line2));
foreach( $val_iter as $value) {
list( $el1, $el2) = $value;
echo ($el1 - $el2); echo ";";
}
echo "\n";
}
You can see from this demo, which statically defines the files as arrays, that this produces:
8;26;10;34;5;6;6;
20;26;3;42;3;54;53;