password_verify( ) 函数 returns 一个空变量

password_verify( ) function returns an empty var

我的 password_verify 函数没有 return 任何东西,但我认为我的代码没问题,我尝试删除字符转义但结果仍然相同,请帮忙 这是我的代码

<?php

if (isset($_POST['submit'])) {
include_once 'db.php';

$uname = stripcslashes($_POST['username']);
$pass = stripcslashes($_POST['userpassword']);
$uname = mysqli_real_escape_string($conn, $_POST['username']);
$pass = mysqli_real_escape_string($conn, $_POST['userpassword']);


 //check if input characters are valid
 if (!preg_match("/^[a-zA-Z0-9]*$/",$uname) || !preg_match("/^[a-zA- Z0-9]*$/",$pass)) {
 header("Location: ../index.php?signin=invalidwords");
 exit();
 }else {    
 //validate username n pwd
 $sql = "SELECT * FROM loginAcc WHERE position='$uname'";
 $result = mysqli_query($conn,$sql);
 $row = mysqli_fetch_array($result,MYSQLI_ASSOC);
 $count = mysqli_num_rows($result);
 $hashedpwd = $row['userpassword'];

 $pw = password_verify($pass,$hashedpwd);
 echo $pass."<br />";
 echo $hashedpwd."<br />";
 echo $pw;
 }
 }else{
 header("Location: ../login.php");
 exit();
 }

password_verify() return bool 值,如果你的 $pw 为假,那么 echo $pw 将不打印任何内容。

尝试用正确和错误的密码测试2个案例。