c# - 为什么我的数组脱离上下文？

Question

我有以下程序:

bool boolFlag=true;
        uint length;
        Console.WriteLine("Give me the length of array a:");
        if (boolFlag=UInt32.TryParse(Console.ReadLine(), out length))
        {
            int[] a = new int[length];
            Console.WriteLine("Give me {0} int numbers for array a[] :", a.Length);
            for (int i = 0; i < a.Length; i++)
            {
                if (boolFlag = Int32.TryParse(Console.ReadLine(), out a[i]))
                {
                    continue;
                }
                else
                {
                    Console.WriteLine("Parsing at Index a[{0}] failed.", i);
                }
            }
        }
        else
        {
            Console.WriteLine("Could not parse length.");
        }


        Console.WriteLine("Give me the length of array b:");
        if (boolFlag = UInt32.TryParse(Console.ReadLine(), out length))
        {
            int[] b = new int[length];
            Console.WriteLine("Give me {0} int numbers for array b[] :", b.Length);
            for (int i = 0; i < b.Length; i++)
            {
                if (boolFlag = Int32.TryParse(Console.ReadLine(), out b[i]))
                {
                    continue;
                }
                else
                {
                    Console.WriteLine("Parsing at Index b[{0}] failed.", i);
                }
            }
        }
        else
        {
            Console.WriteLine("Could not parse length.");
        }





        if (a.Length==b.Length)
        //{
        //    Console.WriteLine("a and b have equal Length");
        //    for (int i = 0; i < a.Length; i++)
        //    {
        //        if (a[i]==b[i])
        //        {
        //            boolFlag = true;
        //            continue;
        //        }
        //        else
        //        {
        //            Console.WriteLine("a[{0}] != b[{0}]", i);
        //        }
        //    }
        //}
        //else
        //{
        //    Console.WriteLine("The arrays don`t have equal length");
        //}
        Console.ReadLine();

当我到达比较部分时，我得到:
错误 1 ​​The name 'a' does not exist in the current context
错误 2 The name 'b' does not exist in the current context

为什么会这样？

我第二次尝试更改代码...声明数组超出语句范围:

int[] a;
        int[] b;
        bool boolFlag=true;
        uint length;
        Console.WriteLine("Give me the length of array a:");
        if (boolFlag=UInt32.TryParse(Console.ReadLine(), out length))
        {
            a = new int[length];
            Console.WriteLine("Give me {0} int numbers for array a[] :", a.Length);
            for (int i = 0; i < a.Length; i++)
            {
                if (boolFlag = Int32.TryParse(Console.ReadLine(), out a[i]))
                {
                    continue;
                }
                else
                {
                    Console.WriteLine("Parsing at Index a[{0}] failed.", i);
                }
            }
        }
        else
        {
            Console.WriteLine("Could not parse length.");
        }


        Console.WriteLine("Give me the length of array b:");
        if (boolFlag = UInt32.TryParse(Console.ReadLine(), out length))
        {
            b = new int[length];
            Console.WriteLine("Give me {0} int numbers for array b[] :", b.Length);
            for (int i = 0; i < b.Length; i++)
            {
                if (boolFlag = Int32.TryParse(Console.ReadLine(), out b[i]))
                {
                    continue;
                }
                else
                {
                    Console.WriteLine("Parsing at Index b[{0}] failed.", i);
                }
            }
        }
        else
        {
            Console.WriteLine("Could not parse length.");
        }





        if (a.Length==b.Length)
        {
        //    Console.WriteLine("a and b have equal Length");
        //    for (int i = 0; i < a.Length; i++)
        //    {
        //        if (a[i]==b[i])
        //        {
        //            boolFlag = true;
        //            continue;
        //        }
        //        else
        //        {
        //            Console.WriteLine("a[{0}] != b[{0}]", i);
        //        }
        //    }
        }
        else
        {
        //    Console.WriteLine("The arrays don`t have equal length");
        }


        Console.ReadLine();

现在我得到:

错误 1 ​​使用未分配的局部变量 'b'
错误 2 使用未分配的局部变量 'a'

Answer 1

因为您在它们的范围之外使用 a 和 b 。将它们的声明移动到代码的开头并将它们分配给 null。请注意，您可能需要考虑在用户输入错误长度时停止执行。在显示错误信息后放置return;。

此外，请考虑查看 this关于变量作用域的有用文章。