PHP检查字符串是否在3到20个字符之间
我正在为php做一个用户名检查，我需要检查字符串是否在3到20个字符之间，我已经尝试过了，但它不起作用！ 这是我的代码示例的链接，我不知道如何使用stackoverflow：(PHP检查字符串是否在3到20个字符之间,php,Php,我正在为php做一个用户名检查，我需要检查字符串是否在3到20个字符之间，我已经尝试过了，但它不起作用！ 这是我的代码示例的链接，我不知道如何使用stackoverflow：( if（isset（$\u POST['submit']））{ $user=trim（mysql\u real\u escape\u字符串（$\u POST['user']）； $email=trim（mysql\u real\u escape\u string（$\u POST['email']）； $pass1=tri
if（isset（$\u POST['submit']））{
$user=trim（mysql\u real\u escape\u字符串（$\u POST['user']）；
$email=trim（mysql\u real\u escape\u string（$\u POST['email']）；
$pass1=trim（mysql\u real\u escape\u字符串（$\u POST['pass1']）；
$pass2=trim（mysql\u real\u escape\u字符串（$\u POST['pass2']）；
如果（！empty（$user）&&！empty（$email）&&！empty（$pass1）&&！empty（$pass2））{
if（ctype_alnum（$user））{
if（过滤变量（$email，过滤验证电子邮件））{
if（strlen（$user）<3）{
如果（strlen（$user）>20）{
$query1=mysql_query（“从用户名为“$user”的用户中选择用户名”）；
$query2=mysql_query（“选择来自用户的电子邮件，其中电子邮件=“$email”）；
$count1=mysql\u num\u行（$query1）；
$count2=mysql\u num\u行（$query2）；
如果（$count1==0&&$count2==0）{
如果（$pass1==$pass2）{
}否则{
$output='错误，密码不匹配！'；
}
}否则{
$output='错误、用户名和电子邮件被占用！'；
}
如果（$count1==1）{
$output='错误，用户名被占用！'；
}
如果（$count2==1）{
$output='错误，已接收电子邮件！'；
}
}否则{
$output='CC错误，用户名必须为3-20个字符！'；
}
}否则{
$output='xx错误，用户名必须为3-20个字符！'；
}
}否则{
$output='错误，无效电子邮件！'；
}
}否则{
$output='错误，用户名必须是字母数字！'；
}
}否则{
$output='错误，缺少字段！'；
}
}
if (strlen($user) >= 3 && strlen($user) <= 20) {
...
}
if（strlen（$user）>=3&&strlen（$user）标准MYSQL已弃用，不应再使用。如果您在服务器上升级PHP版本，您将遇到一些麻烦
您应该查看MYSQLI prepared语句或PDO。prepared语句比标准查询安全得多，并自动处理转义字符串等问题
我还将研究如何使用try/catch语句。try/catch语句允许您生成错误消息，而无需构建一个庞大的if语句层，这样可以节省资源和时间。它也更容易看到
此外，我还建议在打开连接或访问数据库之前，对您的post值进行所有检查。在必要之前，最好不要访问或使用数据库
最好只访问和使用数据库的次数尽可能少。通过一个查询而不是两个查询可以提取电子邮件和用户名。然后通过数据循环进行检查。这可以节省数据库活动和资源
我在下面使用您提交的代码提供了一个示例，其中还包括对原始问题的回答
# Start your try/catch statement to check for thrown exceptions (error messages)
try {
# Check for $_POST to initiate script
if( !empty($_POST) ){
# Loop through each post value
foreach( $_POST as $key => $val ){
# Check if each post value is empty and throw and exception and if not set it as a variable
if( !empty($val) ){
${$key} = trim($val);
}
else {
# Throw Exception (error message)
throw new Exception("Error, missing fields.");
}
}
# Check if $user is alphanumeric and is at least 3 to 20 characters (THE ANSWER TO YOUR ORIGINAL QUESTION!!!)
if( !ctype_alnum($user) || strlen($user) < 3 || strlen($user) > 20 ){
# Throw Exception (error message)
throw new Exception("Error, username must be alphanumeric and at least 3 to 20 characters.");
}
# Check if $email is valid
if( filter_var($email, FILTER_VALIDATE_EMAIL) ){
# Throw Exception (error message)
throw new Exception("Error, invalid email.");
}
# Check if $pass1 and $pass2 are the same value
if( $pass1 != $pass2 ){
# Throw Exception (error message)
throw new Exception("Error, passwords do not match.");
}
# Make MYSQLI Connection
$mysqli = new mysqli($servername, $username, $password, $dbname);
if ( $mysqli->connect_errno ) {
# Throw connections error message
throw new Exception("Error, could not connect to database.");
}
# Prepare your query for execution
$stmt = $mysqli->prepare("SELECT `username`,`email` FROM `users` WHERE `username` = ? OR `email` = ?");
# Bind the two parameters to your statement
$stmt->bind_param("ss", $user, $email);
if ( $stmt === false ) {
# Throw Exception (error message)
throw new Exception("Error, could not process data submitted.");
}
# Excecute your query
$stmt->execute();
if ( $stmt === false ) {
# Throw Exception (error message)
throw new Exception("Error, count not execute database query.");
}
# Bind the results to a variable
$stmt->bind_result($users);
# Fetch your data from results
while($stmt->fetch()){
$foundusers = $users;
}
if ( $stmt === false ) {
# Throw Exception (error message)
throw new Exception("Error, could not get results from database.");
}
# Set counters for username and emails found
$usernames = 0;
$emails = 0;
# Loop through each database entry retrieved and check for matching usernames and emails
foreach( $foundusers as $thisuser ){
if( !empty($thisuser["email"]) && $thisuser["email"] == $email ){
# Add 1 to the $emails counter
$emails++;
}
if( !empty($thisuser["username"]) && $thisuser["username"] == $user ){
# Add 1 to the $usernames counter
$usernames++;
}
}
# close your statement
$stmt->close();
#Check if matching usernames OR emails were found
if( $usernames > 0 || $emails > 0 ){
# Check if $usernames and $emails counter is great than 0
if( $usernames >= 1 && $emails >= 1 ){
# Throw Exception (error message)
throw new Exception("Error, username & email are taken.");
}
# Check if $usernames counter is great than 0
if( $usernames >= 1 ) {
# Throw Exception (error message)
throw new Exception("Error, username is taken.");
}
# Check if $emails counter is great than 0
if( $emails >= 1 ) {
# Throw Exception (error message)
throw new Exception("Error, email is taken.");
}
}
}
else {
# Throw Exception (error message)
throw new Exception("Error, could not initiate script.");
}
# Report no usernames were found (only shows if no exceptions are thrown prior to this code)
$output = "<div onclick=\"this.style.display = 'none'\"><header><h1>Success, username & email are available.</h1><a href='#'><i class='fa fa-times'></i></a></header></div>";
}
# Catch any exceptions thrown and output the error
catch( Exception $e ) {
# Check if statement is still open and close it
if($stmt){
$stmt->close();
}
# Create your error response
$output = "<div onclick=\"this.style.display = 'none'\"><header><h1>" . $e->getMessage() . "</h1><a href='#'><i class='fa fa-times'></i></a></header></div>";
}
#启动try/catch语句检查抛出的异常（错误消息）
试一试{
#检查$\u POST以启动脚本
如果（！空（$\u POST））{
#循环遍历每个post值
foreach（$\发布为$key=>$val）{
#检查每个post值是否为空，并抛出和异常，如果不是，则将其设置为变量
如果（！空（$val））{
${$key}=trim（$val）；
}
否则{
#抛出异常（错误消息）
抛出新异常（“错误，缺少字段”）；
}
}
#检查$user是否为字母数字且至少包含3到20个字符（原始问题的答案！！！）
如果（！ctype_alnum（$user）| strlen（$user）<3 | strlen（$user）>20）{
#抛出异常（错误消息）
抛出新异常（“错误，用户名必须是字母数字，并且至少有3到20个字符。”）；
}
#检查$email是否有效
if（过滤变量（$email，过滤验证电子邮件））{
#抛出异常（错误消息）
抛出新异常（“错误，无效电子邮件”）；
}
#检查$pass1和$pass2的值是否相同
如果（$pass1！=$pass2）{
#抛出异常（错误消息）
抛出新异常（“错误，密码不匹配。”）；
}
#建立MYSQLI连接
$mysqli=newmysqli（$servername、$username、$password、$dbname）；
如果（$mysqli->connect\u errno）{
#抛出连接错误消息
抛出新异常（“错误，无法连接到数据库。”）；
}
#准备要执行的查询
$stmt=$mysqli->prepare（“选择`username`、`email`FROM`users`WHERE`username`=？或`email`=？”；
#将这两个参数绑定到语句中
$stmt->bind_参数（“ss”、$user、$email）；
如果（$stmt==false）{
#抛出异常（错误消息）
抛出新异常（“错误，无法处理提交的数据”）；
}
#超越你的疑问
$stmt->execute（）；
如果（$stmt==false）{
#抛出异常（错误消息）
抛出新异常（“错误，计数不执行数据库查询”）；
}
#绑上绳子
# Start your try/catch statement to check for thrown exceptions (error messages)
try {
# Check for $_POST to initiate script
if( !empty($_POST) ){
# Loop through each post value
foreach( $_POST as $key => $val ){
# Check if each post value is empty and throw and exception and if not set it as a variable
if( !empty($val) ){
${$key} = trim($val);
}
else {
# Throw Exception (error message)
throw new Exception("Error, missing fields.");
}
}
# Check if $user is alphanumeric and is at least 3 to 20 characters (THE ANSWER TO YOUR ORIGINAL QUESTION!!!)
if( !ctype_alnum($user) || strlen($user) < 3 || strlen($user) > 20 ){
# Throw Exception (error message)
throw new Exception("Error, username must be alphanumeric and at least 3 to 20 characters.");
}
# Check if $email is valid
if( filter_var($email, FILTER_VALIDATE_EMAIL) ){
# Throw Exception (error message)
throw new Exception("Error, invalid email.");
}
# Check if $pass1 and $pass2 are the same value
if( $pass1 != $pass2 ){
# Throw Exception (error message)
throw new Exception("Error, passwords do not match.");
}
# Make MYSQLI Connection
$mysqli = new mysqli($servername, $username, $password, $dbname);
if ( $mysqli->connect_errno ) {
# Throw connections error message
throw new Exception("Error, could not connect to database.");
}
# Prepare your query for execution
$stmt = $mysqli->prepare("SELECT `username`,`email` FROM `users` WHERE `username` = ? OR `email` = ?");
# Bind the two parameters to your statement
$stmt->bind_param("ss", $user, $email);
if ( $stmt === false ) {
# Throw Exception (error message)
throw new Exception("Error, could not process data submitted.");
}
# Excecute your query
$stmt->execute();
if ( $stmt === false ) {
# Throw Exception (error message)
throw new Exception("Error, count not execute database query.");
}
# Bind the results to a variable
$stmt->bind_result($users);
# Fetch your data from results
while($stmt->fetch()){
$foundusers = $users;
}
if ( $stmt === false ) {
# Throw Exception (error message)
throw new Exception("Error, could not get results from database.");
}
# Set counters for username and emails found
$usernames = 0;
$emails = 0;
# Loop through each database entry retrieved and check for matching usernames and emails
foreach( $foundusers as $thisuser ){
if( !empty($thisuser["email"]) && $thisuser["email"] == $email ){
# Add 1 to the $emails counter
$emails++;
}
if( !empty($thisuser["username"]) && $thisuser["username"] == $user ){
# Add 1 to the $usernames counter
$usernames++;
}
}
# close your statement
$stmt->close();
#Check if matching usernames OR emails were found
if( $usernames > 0 || $emails > 0 ){
# Check if $usernames and $emails counter is great than 0
if( $usernames >= 1 && $emails >= 1 ){
# Throw Exception (error message)
throw new Exception("Error, username & email are taken.");
}
# Check if $usernames counter is great than 0
if( $usernames >= 1 ) {
# Throw Exception (error message)
throw new Exception("Error, username is taken.");
}
# Check if $emails counter is great than 0
if( $emails >= 1 ) {
# Throw Exception (error message)
throw new Exception("Error, email is taken.");
}
}
}
else {
# Throw Exception (error message)
throw new Exception("Error, could not initiate script.");
}
# Report no usernames were found (only shows if no exceptions are thrown prior to this code)
$output = "<div onclick=\"this.style.display = 'none'\"><header><h1>Success, username & email are available.</h1><a href='#'><i class='fa fa-times'></i></a></header></div>";
}
# Catch any exceptions thrown and output the error
catch( Exception $e ) {
# Check if statement is still open and close it
if($stmt){
$stmt->close();
}
# Create your error response
$output = "<div onclick=\"this.style.display = 'none'\"><header><h1>" . $e->getMessage() . "</h1><a href='#'><i class='fa fa-times'></i></a></header></div>";
}