substr_replace：整个字符串(从这里结束) 替换成这个变量 从什么开始(默认从下标0开始)
<!DOCTYPE html> <html lang="zh"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title></title> </head> <body> <form method="get"> <input type="text" name="username" id=""> <input type="submit" value="提交"> </form> </body> </html> <?php error_reporting(0); $new_substring="cyg&liwen"; echo $new_string=substr_replace($_GET['username'],$new_substring,6); ?>
