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    ▪一个php验证码的封装类      验证码类，validationcode.class.php   代码示例: <?php /** * 验证码类 * edit www. */ class ValidationCode { private $width; private $height; private $codeNum; private $image; //图像资源 private $disturbColorNum; private.........

    ▪php中substr字符串截取函数实例详解      php中的substr函数。 substr() 函数 返回字符串的一部分。 语法：substr(string,start,length)。     string：必需。规定要返回其中一部分的字符串。     start：必需。规定在字符串的何处开始。正数.........

    ▪php中substr字符串截取函数的用法示例      字符串截取函数substr的例子：   代码示例: <? //by www. $rest = substr("abcdef", 1); // returns "bcdef" echo 'substr("abcdef", 1) returns ' . $rest . "<br>"; $rest = substr("abcdef", 1, 3); // returns "bcd" echo 'substr("a.........

代码示例:

<?php
/**
* 验证码类
* edit www.
*/
class ValidationCode {
private $width;
private $height;
private $codeNum;
private $image; //图像资源
private $disturbColorNum;
private $checkCode;
function __construct($width=80, $height=20, $codeNum=4){
$this->width=$width;
$this->height=$height;
$this->codeNum=$codeNum;
$this->checkCode=$this->createCheckCode();
$number=floor($width*$height/15);

if($number > 240-$codeNum){
$this->disturbColorNum= 240-$codeNum;
}else{
$this->disturbColorNum=$number;
}

}
//通过访问该方法向浏览器中输出图像
function showImage($fontFace=""){
//第一步：创建图像背景
$this->createImage();
//第二步：设置干扰元素
$this->setDisturbColor();
//第三步：向图像中随机画出文本
$this->outputText($fontFace);
//第四步：输出图像
$this->outputImage();
}

//通过调用该方法获取随机创建的验证码字符串
function getCheckCode(){
return $this->checkCode;
}
private function createImage(){
//创建图像资源 //www.
$this->image=imagecreatetruecolor($this->width, $this->height);
//随机背景色
$backColor=imagecolorallocate($this->image, rand(225, 255), rand(225,255), rand(225, 255));
//为背景添充颜色
imagefill($this->image, 0, 0, $backColor);
//设置边框颜色
$border=imagecolorallocate($this->image, 0, 0, 0);
//画出矩形边框
imagerectangle($this->image, 0, 0, $this->width-1, $this->height-1, $border);
}
private function setDisturbColor(){
for($i=0; $i<$this->disturbColorNum; $i++){
$color=imagecolorallocate($this->image, rand(0, 255), rand(0, 255), rand(0, 255));
imagesetpixel($this->image, rand(1, $this->width-2), rand(1, $this->height-2), $color);
}
for($i=0; $i<10; $i++){
$color=imagecolorallocate($this->image, rand(200, 255), rand(200, 255), rand(200, 255));
imagearc($this->image, rand(-10, $this->width), rand(-10, $this->height), rand(30, 300), rand(20, 200), 55, 44, $color);
}
}
private function createCheckCode(){
//这里主要产生随机码，从2开始是为了区分1和l
$code="23456789abcdefghijkmnpqrstuvwxyzABCDEFGHIJKMNPQRSTUVWXYZ";
$string='';
for($i=0; $i < $this->codeNum; $i++){
$char=$code{rand(0, strlen($code)-1)};
$string.=$char;
}
return $string;
}
private function outputText($fontFace=""){
for($i=0; $i<$this->codeNum; $i++){
$fontcolor=imagecolorallocate($this->image, rand(0, 128), rand(0, 128), rand(0, 128));
if($fontFace==""){
$fontsize=rand(3, 5);
$x=floor($this->width/$this->codeNum)*$i+3;
$y=rand(0, $this->height-15);
imagechar($this->image,$fontsize, $x, $y, $this->checkCode{$i},$fontcolor);
}else{
$fontsize=rand(12, 16);
$x=floor(($this->width-8)/$this->codeNum)*$i+8;
$y=rand($fontSize+5, $this->height);
imagettftext($this->image,$fontsize,rand(-30, 30),$x,$y ,$fontcolor, $fontFace, $this->checkCode{$i});
}
}
}

//输出图象信息
private function outputImage() {
if(imagetypes() & IMG_GIF){
header("Content-Type:image/gif");
imagepng($this->image);
}else if(imagetypes() & IMG_JPG){
header("Content-Type:image/jpeg");
imagepng($this->image); //www.
}else if(imagetypes() & IMG_PNG){
header("Content-Type:image/png");
imagepng($this->image);
}else if(imagetypes() & IMG_WBMP){
header("Content-Type:image/vnd.wap.wbmp");
imagepng($this->image);
}else{
die("PHP不支持图像创建");
}
}
function __destruct(){
imagedestroy($this->image);
}
}
?>

代码示例:

<?php
session_start();
include "validationcode.class.php";
$code=new ValidationCode(80, 20, 4);
$code->showImage(); //输出到页面中供 注册或登录使用
$_SESSION["code"]=$code->getCheckCode(); //将验证码保存到服务器中
?>

代码示例:

<?php
$rest = substr("abcdef", -1);    // returns "f"
echo $rest.'<br />';
$rest = substr("abcdef", -2);    // returns "ef"
echo $rest.'<br />';
$rest = substr("abcdef", -3, 1); // returns "d"
echo $rest.'<br />';
?>

代码示例:

<?php
$rest = substr("abcdef", 0, -1);  // returns "abcde"
echo $rest.'<br />';
$rest = substr("abcdef", 2, -1);  // returns "cde"
echo $rest.'<br />';
$rest = substr("abcdef", 4, -4);  // returns ""
echo $rest.'<br />';
$rest = substr("abcdef", -3, -1); // returns "de"
echo $rest.'<br />';
?>

代码示例:

<?php
echo substr('abcdef', 1);     // bcdef
echo '<br />';
echo substr('abcdef', 1, 3);  // bcd
echo '<br />';
echo substr('abcdef', 0, 4);  // abcd
echo '<br />';
echo substr('abcdef', 0, 8);  // abcdef
echo '<br />';
echo substr('abcdef', -1, 1); // f
echo '<br />';
// Accessing single characters in a string
// can also be achieved using "square brackets"
$string = 'abcdef';
echo $string[0];                 // a
echo '<br />';
echo $string[3];                 // d
echo '<br />';
echo $string[strlen($string)-1]; // f
echo '<br />';
?>

代码示例:

<?php
//removes string from the end of other
function removeFromEnd($string, $stringToRemove)
{
    // 获得需要移除的字符串的长度
$stringToRemoveLen = strlen($stringToRemove);
// 获得原始字符串的长度
    $stringLen = strlen($string);
   
// 计算出需要保留字符串的长度
    $pos = $stringLen - $stringToRemoveLen;

    $out = substr($string, 0, $pos);
    return $out;
}
$string = 'nowamagic.jpg.jpg';
$result = removeFromEnd($string, '.jpg');
echo $result;
?>

代码示例:

<?php
/**
* 截取字符串，中间加省略号
* edit www.
*/
$file = "Hellothisfilehasmorethan30charactersandthisfayl.exe";
function funclongwords($file)
{
if (strlen($file) > 30)
{
$vartypesf = strrchr($file,".");
// 获取字符创总长度
$vartypesf_len = strlen($vartypesf);
// 截取左边15个字符
$word_l_w = substr($file,0,15);
// 截取右边15个字符
$word_r_w = substr($file,-15);
$word_r_a = substr($word_r_w,0,-$vartypesf_len);
return $word_l_w."...".$word_r_a.$vartypesf;
}
else
return $file;
}
// RETURN: Hellothisfileha...andthisfayl.exe
$result = funclongwords($file);
echo $result;
?>

代码示例:

<?php
$text = 'welcome to nowamagic, I hope you can find something you wanted.';
$result = textLimit($text, 30);
echo $result;
function textLimit($string, $length, $replacer = '...')
{
  if(strlen($string) > $length)
  return (preg_match('/^(.*)\W.*$/', substr($string, 0, $length+1), $matches) ? $matches[1] : substr($string, 0, $length)) . $replacer;
 
  return $string;
}
?>

代码示例:

<?php
/**
* 格式化字符串
* edit www.
*/
function str_format_number($String, $Format)
{
    if ($Format == '') return $String;
    if ($String == '') return $String;
    $Result = '';
    $FormatPos = 0;
    $StringPos = 0;
    while ((strlen($Format) - 1) >= $FormatPos)
{
        //If its a number => stores it
        if (is_numeric(substr($Format, $FormatPos, 1)))
{
            $Result .= substr($String, $StringPos, 1);
            $StringPos++;
        //If it is not a number => stores the caracter
        }
else
{
            $Result .= substr($Format, $FormatPos, 1);
        }
        //Next caracter at the mask.
        $FormatPos++;
    }
    return $Result;
}
// For phone numbers at Buenos Aires, Argentina
// Example 1:
    $String = "8607562337788";
    $Format = "+00 0000 0000000";
    echo str_format_number($String, $Format);
echo '<br />';
// Example 2:
    $String = "8607562337788";
    $Format = "+00 0000 00.0000000";
    echo str_format_number($String, $Format);
echo '<br />';
// Example 3:
    $String = "8607562337788";
    $Format = "+00 0000 00.000 a";
    echo str_format_number($String, $Format);
echo '<br />';
?>

代码示例:

<?
//by www.
$rest = substr("abcdef", 1); // returns "bcdef"
echo 'substr("abcdef", 1) returns ' . $rest . "<br>";
$rest = substr("abcdef", 1, 3); // returns "bcd"
echo 'substr("abcdef", 1, 3) returns ' . $rest . "<br>";
$rest = substr("abcdef", -1); // returns "f"
echo 'substr("abcdef", -1) returns ' . $rest . "<br>";
$rest = substr("abcdef", -2); // returns "ef"
echo 'substr("abcdef", -2) returns ' . $rest . "<br>";
$rest = substr("abcdef", -3, 1); // returns "d"
echo 'substr("abcdef", -3, 1) returns ' . $rest . "<br>";
$rest = substr("abcdef", 1, -1); // returns "bcde"
echo 'substr("abcdef", 1, -1) returns ' . $rest . "<br>";
?>