Summary of image processing and file operation methods in php (with code)

This article brings you a summary of image processing and file operation methods in PHP (with code). It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

Part One: Image Processing

First: Image Scaling

Image scaling, no transparent color processing
The code is as follows:

 function thumn($background, $width, $height, $newfile) {
 list($s_w, $s_h)=getimagesize($background);//获取原图片高度、宽度
 if ($width && ($s_w < $s_h)) {
 $width = ($height / $s_h) * $s_w;
 } else {
 $height = ($width / $s_w) * $s_h;
 }
 $new=imagecreatetruecolor($width, $height);
 $img=imagecreatefromjpeg($background);
 imagecopyresampled($new, $img, 0, 0, 0, 0, $width, $height, $s_w, $s_h);
 imagejpeg($new, $newfile);
 imagedestroy($new);
 imagedestroy($img);
 }
 thumn("images/hee.jpg", 200, 200, "./images/hee3.jpg");

Second: Adding watermarks to pictures

Adding text watermarks to pictures

 function mark_text($background, $text, $x, $y){
 $back=imagecreatefromjpeg($background);
 $color=imagecolorallocate($back, 0, 255, 0);
 imagettftext($back, 20, 0, $x, $y, $color, "simkai.ttf", $text);
 imagejpeg($back, "./images/hee7.jpg");
 imagedestroy($back);
 }
 mark_text("./images/hee.jpg", "细说PHP", 150, 250);

Part 2: Variable variables

1, Variable variables

2. Variable function

  $a="function";
  $a teststr()
  { 
  return "adfasd";
  }
  $b="teststr";
  echo $b();

3. Variable class

$a="b";
$$a="c";
echo $b;

Part 3: File operation (PHP operation file)

One: readfile() function

Example one:

 <?php
     echo readfile("webdictionary.txt");
?>

Two: fopen();Open file
(1). fopen(1,2);
1. File name
2. Open mode
Mode Description
r Open the file as read-only. The file pointer starts at the beginning of the file.
w Open the file for writing only. Delete the contents of the file or create a new file if it does not exist. The file pointer starts at the beginning of the file.
a Open the file for writing only. Existing data in the file will be preserved. The file pointer starts at the end of the file. Create a new file if the file does not exist.
x Create a new file to write only. Returns FALSE and an error if the file already exists.

r Open the file for reading/writing, and the file pointer starts at the beginning of the file.
w Open the file for reading/writing. Delete the file contents or create a new file if it does not exist. The file pointer starts at the beginning of the file.
a Open the file for reading/writing. Data already in the file will be retained. The file pointer starts at the end of the file. Create new file if it does not exist.
x Create new files for reading/writing. Returns FALSE and an error if the file already exists.
        die
                                                                                                                                                                                           .
#(3). filesize() Get the file size
filesize(1);
1.File name

(4).fclose(1) Close the file pointer
fclose(1)
1. File pointer

Example 2:

<?php
$myfile = fopen("webdictionary.txt", "r") or die("Unable to open file!");
echo fread($myfile,filesize("webdictionary.txt"));
fclose($myfile);
?>

(5) fgets(1) Read a line of data

1 .File pointer

Example 3:

<?php
$myfile = fopen("webdictionary.txt", "r") or die("Unable to open file!");
echo fgets($myfile);
fclose($myfile);
?>

Example 4: feof(1) Detect whether the file has reached the end

<?php
$myfile = fopen("webdictionary.txt", "r") or die("Unable to open file!");
// 输出单行直到 end-of-file
while(!feof($myfile)) {
  echo fgets($myfile) . "<br>";
}
fclose($myfile);
?>

(6) fgetc(1) ) Read a character

(7) fwrite() writes to the file

Example 5:

<?php
$myfile = fopen("newfile.txt", "w") or die("Unable to open file!");
    $txt = "Bill Gates\n";
    fwrite($myfile, $txt);
fclose($myfile);
?>

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