PHP common library functions

1) Time and date

mainly involves time() and date();

<?php //获取时间戳
echo time();
echo &#39;<br/>';
//echo date_default_timezone_get();
//设置时区
date_default_timezone_set('Asia/Shanghai');
//按指定格式输出数据
echo date('Y-m-d H:i:s');
echo '<br>';
//将时间戳转为日期
echo date('Y-m-d H:i:s','2000');

2) Operation of json format data:

mainly involves json_encode() and json_decode();

<?php //将数组转成json格式的数据
$arr=array(2,7,9,&#39;hello&#39;,&#39;jason&#39;,array(&#39;name&#39;=>'lily','age'=>23));
print_r($arr);
echo '<br>';
echo json_encode($arr);

//将键值对对象转成json格式的数据
$obj=array('h'=>'hello','w'=>'world',array(3,5,7));
echo '<br>';
print_r($obj);
echo '<br>';
echo json_encode($obj);

//将json格式的数据转成键值对对象
$objJson='{"h":"hello","w":"world","0":[5,7,8]}';
$myObj=json_decode($objJson);
echo '<br>';
print_r($myObj);
echo '<br>';
echo $myObj->w;

3) File operations:

fopen(), fwrite(), fclose(), fgets(), file_get_contents(), etc.;

<?php /**
 * 写数据
 */
//创建文件标识,注：加@可忽略php的警告
$wf=@fopen(&#39;data&#39;,&#39;w&#39;);
if($wf){
    //写入数据到文件
    fwrite($wf,&#39;oh my god&#39;);
//关闭文件流
    fclose($wf);
}else{
    echo &#39;创建文件失败&#39;;
}

/**
 * 读数据
 */
$rf=@fopen('data','r');
//fgets()只读一行
while(!feof($rf)){
    $c
    echo $content;
}
fclose($rf);

//php提供了一个直接获取文件所有内容的方法
echo file_get_contents('data');

4) Generate pictures, for more methods click php image method

<?php //创建图像文件
$img=imagecreate(400,300);
//设置图像的背景色
imagecolorallocate($img,0,0,255);
//绘制一个椭圆 
imageellipse($img,100,100,80,40,imagecolorallocate($img,255,0,0));
//设置头信息来指明图像所属的mime类型
header(&#39;Content-Type:image/png&#39;);
//显示图像
imagepng($img);

5) Watermark pictures

<?php //载入文件
$img=imagecreatefrompng(&#39;header.png&#39;);
//在图片指定位置写上文字
imagestring($img,5,5,5,&#39;I am not a bitch&#39;,imagecolorallocate($img,255,0,0));
//设置头信息来指明mime类型
header(&#39;Content-Type:image/png&#39;);
//显示图像
imagepng($img);

For more details, please refer to the PHP Chinese manual

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The above has introduced the commonly used library functions of PHP, including related content. I hope it will be helpful to friends who are interested in PHP tutorials.