php将数据库查询的结果打印成json格式，怎么做

这是我的代码，输出有问题的那句我标注了。

<code class="php">    $conn = mysqli_connect("localhost:3306", "root", "19961120");
    if($conn){
        mysqli_select_db($conn, "test");
        $result = mysqli_query($conn, "select * from user");
        $users = array();
        for($i=0;$i<mysqli_num_rows mysqli_fetch_row var_dump></mysqli_num_rows></code>

回复内容：

这是我的代码，输出有问题的那句我标注了。

<code class="php">    $conn = mysqli_connect("localhost:3306", "root", "19961120");
    if($conn){
        mysqli_select_db($conn, "test");
        $result = mysqli_query($conn, "select * from user");
        $users = array();
        for($i=0;$i<mysqli_num_rows mysqli_fetch_row var_dump></mysqli_num_rows></code>

好好看看文档，json_decode() 是解析json字符串的，json_encode()才是把数组解析成json字符串