php 总结（6） Json格式数组转换 生成图片水印 读写数据 文件

$arr = array(1,2,3,4,5,6,"hello","nice" );
print_r($arr);
// Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 [5] => 6 [6] => hello [7] => nice )   普通输出
echo "<br>";
echo json_encode($arr);
 // [1,2,3,4,5,6,"hello","nice"]
echo "<br>";
echo $arr[0]."<br>";
// 1
$obj = array('1'=> 3,'2'=>'nice' );
echo json_encode($obj);
// {"1":3,"2":"nice"}
echo "<br>";
print_r($obj[2]);
// nice
$arr = array(1,2,3,4,5,