小编its*_*iao的帖子

为什么这两个函数会产生不同的结果？

var table1 = document.getElementById("table1");
var table2 = document.getElementById("table2");

var register = [
  {att1: 1, att2: 2, att3: 3},
  {att1: 4, att2: 5, att3: 6},
  {att1: 7, att2: 8, att3: 9}
];

//table1.innerHTML = "";
//table2.innerHTML = "";

function drawTable1() {
  for (var i = 0; i < register.length; i++) {
    table1.innerHTML += "<tr><td>" + register[i].att1 + "</td><td>" + register[i].att2 + "</td><td>" + register[i].att3 + "</td></tr>";
  }
}

function drawTable2() {
	for (var i = 0; i < register.length; i++) …

我对网络开发很陌生,现在正在开展一个学校项目.我的登录代码有问题,但我无法弄清楚它是什么.当我提交表单时,页面似乎只是重新加载并且没有设置会话.

我缩短的登录页面:

<?php include "connect.php";

if (isset($POST['login'])) {
    $user_email_username = mysqli_real_escape_string($link, $_POST['email_username']);
    $user_password = mysqli_real_escape_string($link, $_POST['password']);

    $email_username_query = mysqli_query($link, "SELECT * FROM User WHERE email='$user_email_username' OR username='$user_email_username'");

    if (mysqli_num_rows($email_username_query) == 0) {
        $not_registered_error = "It looks like you still don't have an account. <a href=\"signup.php\">Sign up</a>.";
    } else {
        $row = mysqli_fetch_array($email_username_query);
        if (sha1($user_password) != $row['password']) {
            $wrong_password_error = "The password you submitted is wrong.";
        } else {
            $_SESSION['user_id'] = $row['idUser'];
            $_SESSION['user_name'] = $row['name'];
            $_SESSION['user_username'] = $row['username'];
            header("Location: index.php");
        } …

鉴于这样的假设情况:

int val1, val2, val3, choice;
while (expression) {
    cin >> choice;
    if (choice == 1) {
        val1 += expression;
    } else if (choice == 2) {
        val2 += expression;
    } else if (choice == 3) {
        val3 += expression;
    } else {
        expressions..;
    }
}

有没有办法将变量名称视为字符串,以便能够"组合"它们？这可能是有用的,例如在上面的例子中,甚至更好的在for循环中,将计数器值添加到变量名称,以便在每个循环中调用不同的变量.

有了这样的功能,我上面的例子会变成:

int val1, val2, val3, choice;
while (expression) {
    cin >> choice;
    if (choice == 1 || choice == 2 || choice == 3) {
        ['val' + choice] += expression;
    } else { …