我正在研究一个问题，我已经尝试过用for循环来尝试的所有方法，但是由于我只是从C＃和整个编程领域入手，所以我不知道如何使它起作用几个星期前。
编写一个输入五个数字的应用程序。读取每个数字时，如果数组中不存在该数字，请搜索该数组，然后输出单词“ new”，然后将数字插入到数组中。如果数字确实存在于数组中，则输出“存在”。输入所有五个数字后，输出数组的内容。
这是我到目前为止所拥有的。感谢您的帮助
using System;
public class Program
{
// Main method begins execution of C# application
public static void Main(string[] args)
{
int[] array = new int[5];
for (int i = 0; i < array.Length; i++)
{
Console.WriteLine("Enter a number:");
array[i] = Convert.ToInt32(Console.ReadLine());
for (int a = 0; a < 5; a++)
{
if (array[i] != array[a])
{
array[i] = int.Parse(Console.ReadLine());
Console.WriteLine("new\n");
}
}
array[i] = int.Parse(Console.ReadLine());
Console.WriteLine("exists\n");
}
Console.WriteLine(array);
Console.ReadKey();
}
} // end class
答案 0 :(得分：1)
首先，在实际开始编写代码之前，请先考虑一下解决方案
Contains方法来完成。我们将执行此操作，直到结构的Count等于5。
供参考，请使用此While loop，Hashset.Contains和Hashset
尝试一下：
var numbers = new HashSet<int>();
while(numbers.Count < 5)
{
Console.WriteLine("Enter a number:"); //1.
var number = Convert.ToInt32(Console.ReadLine());
if (numbers.Contains(number)) // 2.
{
Console.WriteLine("exists\n"); //3.
continue;
}
Console.WriteLine("new\n"); //4.
numbers.Add(number);
}
foreach (var n in numbers)
{
Console.WriteLine(n);
}
答案 1 :(得分：0)
您的代码有几个问题。如果成功，则仅应增加数组索引-否则，缺失值将为零。在用户输入无效值的情况下验证输入也是一个好主意。您可以使用linq来检查值是否已存在于数组中：
这里是一个示例：
static void Main(string[] args)
{
int[] array = new int[5];
var index = 0;
while (index < array.Length)
{
Console.WriteLine("Enter a number:");
var input = Console.ReadLine();
var value = 0;
if (!int.TryParse(input, out value))
{
Console.WriteLine("Error - value entered was not a number");
}
else
{
var match = array.Where(a => a == value);
if (match.Any())
{
Console.WriteLine("exists\n");
}
else
{
array[index] = value;
Console.WriteLine("new\n");
index++;
}
}
}
foreach (var item in array)
{
Console.WriteLine(item);
}
Console.ReadKey();
}
答案 2 :(得分：0)
在.Any()中使用System.Linq。另外，您无需在循环中连续获取用户输入：
using System;
using System.Linq;
public class Program
{
// Main method begins execution of C# application
public static void Main(string[] args)
{
int[] array = new int[5];
for (int i = 0; i < array.Length; i++)
{
Console.WriteLine("Enter a number:");
// Get user input and convert to integer:
int input = Convert.ToInt32(Console.ReadLine());
// Check if given input is already in the array:
if (! array.Any(number => number == input))
{
array[i] = input;
Console.WriteLine("new\n");
}
else
{
Console.WriteLine("exists\n");
}
}
// Print the contents of array separated by ','
Console.WriteLine(string.Join(", ", array));
Console.ReadKey();
}
}
编辑：如果您希望用户完全填充数组，则可以使用另一个变体：
using System;
using System.Linq;
public class Program
{
public static void Main(string[] args)
{
// Btw, if this is not an array of nullables,
// we will not be able to insert a zero later, as
// we will treat them as duplicates.
int?[] array = new int?[5];
for (int i = 0; i < array.Length; i++)
{
Console.WriteLine("Enter a number:");
int input = 0;
bool duplicateAttempt = false;
do {
// Get and convert the input.
input = Convert.ToInt32(Console.ReadLine());
// See if this number is already in.
duplicateAttempt = array.Contains(input);
// Report if we attempt to insert a duplicate.
if (duplicateAttempt) Console.WriteLine("exists");
}
while (duplicateAttempt); // Keep asking while we don't get a unique number.
array[i] = input; // Store the number
Console.WriteLine("new");
}
// Print the contents of array separated by ','
Console.WriteLine(string.Join(", ", array));
Console.ReadKey();
}
}
答案 3 :(得分：0)
这似乎是一个家庭作业问题，所以我认为解释您做错了什么并告诉您应该做些什么……
这不会帮助您学习复制和粘贴其他人的答案。
using System;
public class Program
{
// Main method begins execution of C# application
public static void Main(string[] args)
{
int[] array = new int[5];
for (int i = 0; i < array.Length; i++)
{
Console.WriteLine("Enter a number:");
// you are putting the value into your array here. so it will always 'exist' below
array[i] = Convert.ToInt32(Console.ReadLine());
// you need to do this check before you insert the number into the array
// put the ReadLine into a variable, not directly into the array.
// then check if it's in the array already
for (int a = 0; a < 5; a++)
{
if (array[i] != array[a])
{
// here you are trying to read another value from the user.
// Console.ReadLine() will always wait for user input
// use the variable from above. but only after you have looped through all the items.
// and verified that it is not present
array[i] = int.Parse(Console.ReadLine());
Console.WriteLine("new\n");
}
}
// this is the third time you have assigned the number to the array
// and the third time you've asked for user input per loop
array[i] = int.Parse(Console.ReadLine());
Console.WriteLine("exists\n");
}
Console.WriteLine(array);
Console.ReadKey();
}
} // end class
总结：
您需要运行5次的for循环。
for循环将执行以下操作：