Question

我尝试使用以下代码通过while循环求和数组的元素

Here is the errors.php file 

<?php if(count($errors) > 0): ?>
<div class="error">
    <?php foreach ($errors as $error): ?>
    <p><?php echo $error; ?></p>
    <?php endforeach ?>
</div>
<?php endif ?>

但是它会引发错误

Here is the form section that I created in HTML

 <!-- Login page container -->
              <form method="post" action="register.php">
    <!-- display validation errors here --> 
    <?php include('errors.php'); ?> 

  <div class="container">
    <h1>Register</h1>
    <p>Please fill in this form to create an account.</p>
    <hr>

    <label for="firstname"><b>First Name</b></label>
    <input type="text" placeholder="Enter first name" name="firstname" required>

    <label for="lastname"><b>Last Name</b></label>
    <input type="text" placeholder="Enter last name" name="lastname" required>

    <label for="streetaddress"><b>Street Address</b></label>
    <input type="text" placeholder="Enter Street Address" name="streetaddress" required>

    <label for="city"><b>City</b></label>
    <input type="text" placeholder="City" name="city" required>

    <label for="state"><b>State</b></label>
    <input type="text" placeholder="Enter State" name="state" required>

    <label for="zipcode"><b>Zip Code</b></label>
    <input type="text" placeholder="Enter Zip Code" name="zipcode" required>

    <label for="phonenumber"><b>Phone Number</b></label>
    <input type="text" placeholder="Enter Phone Number" name="phonenumber" required>


    <label for="email"><b>Email</b></label>
    <input type="text" placeholder="Enter Email" name="email" value="<?php echo $email; ?>">

    <label for="password"><b>Password</b></label>
    <input type="password" placeholder="Enter Password" name="password" value="<?php echo $password; ?>">

    <p>By creating an account you agree to our <a href="#">Terms & Privacy</a>.</p>
    <button type="submit" name= "register" class="registerbtn">Register</button>
  </div>

  <div class="container signin">
    <p>Already have an account? <a href="internallogin.php">Sign in</a>.</p>
  </div>
           </form>

我也尝试使用return def sum(input: Array[Int]): Int = { var i=0; while(i<input.length) { sum=i+input(i); i=i+1; } sum }，但出现了另一个错误

<console>:17: error: reassignment to val
  sum= (i+input(i))
     ^
<console>:21: error: missing argument list for method 
sum Unapplied methods are only converted to functions when a function type is expected.
You can make this conversion explicit by writing `sum _` or `sum(_)` instead of `sum`.

如何使用while循环求和数组的元素？

Answer 1

我认为您要这样做的是


def sum(input:Array[Int]):Int = {
  var i, res = 0;
  while(i < input.length) {
  res = res + input(i); // and not res=i+input(i);
   i = i + 1;
  }
  res
}

这基本上是使用累加器变量res来累加Array的不同值，而不能使用sum这是它的方法名称。

Answer 2

def sum(input: Array[Int]): Int = input.sum

如果某个东西有内置的例程，那么最好使用它。如果这只是编程工作，那么您不应该使用var和while，而是使用foldLeft或递归例程是更好的解决方案。

Answer 3

在不使用while循环或vars的情况下，汇总列表的方法很少。

val l = List(1,2,3,4,5)

l.reduce((a,b) => a + b)
l.foldLeft(0)((a,b) => a + b)

def sum(l: List[Int]): Int = l match {
  case Nil => 0
  case head :: tail => head + sum(tail)
}

sum(l)

它们应该总计为15。

通过while循环的数组元素总和

3 个答案: