我在为三位数做这件事时遇到了一些麻烦。我可以用两位数字来做，但当我在字符串TwoDigit中添加if语句时，它会告诉我检测到无法访问的代码。这就是我的尝试： -
{
class Program
{
static string[] digitWords =
{ "zero", "one", "two", "three", "four",
"five", "six", "seven", "eight", "nine",
"ten", "eleven", "twelve", "thirteen", "fourteen",
"fifteen", "sixteen", "seventeen", "eighteen", "nineteen" };
static string[] tenWords =
{ "", "", "twenty", "thirty", "forty",
"fifty", "sixty", "seventy", "eighty", "ninety" };
static string[] hundredWords = { "One-hundred", "two-hundred",
"three-hundred", "four-hundred", "five-hundred", "six-hundred",
"seven-hundred", "eight-hundred", "nine-hundred"}
static string TwoDigit(int num)
{
if (num < 0 || num > 99) return "";
if (num < 20) return digitWords[num];
if (num % 10 == 0)
return tenWords[num / 10];
else
return tenWords[num / 10] + "-" + digitWords[num % 10];
if (num % 100 == 0)
return digitWords[num / 100] + "-" + hundredWords[num % 100];
else
return digitWords[num / 100] + "-" + hundredWords[num % 100] + "-" + digitWords[num % 100];
}
static void Main(string[] args)
{
for (int i = 0; i <= 19; i++)
Console.WriteLine("{0}: {1}", i, TwoDigit(i));
for (int i = 20; i <= 99; i +=7)
Console.WriteLine("{0}: {1}", i, TwoDigit(i));
for (int i = 100; i <= 1100; i += 7)
Console.WriteLine("{0}: {1}", i, TwoDigit(i));
}
}
}
答案 0 :(得分：0)
您可以更清楚地了解错误发生的位置，但我可以看到TwoDigit()的后半部分无法访问。由于if语句返回之前的两种情况，下面的代码都无法执行。 return语句退出方法，并且不执行方法中的其他语句。这就是它无法到达的原因。
您可以在我的文章Converting Numbers to Words中提供的代码中看到我是如何做到的。
答案 1 :(得分：0)
在两个分支中都有return的代码 - 因为if条件之后的结果代码永远不会被执行：
if (condition)
{
return 1;
}
else
{
return 2;
}
// never will reach here
var i = 1; // unreachable code.
答案 2 :(得分：0)
对于您遇到的错误的特定问题：
您的第3个if语句将始终返回一个值，因此您永远不会达到第4个if语句。 （记住，一旦你回来，你已完成该功能，其余的代码将不会被执行！）
此外，您可能需要在此处重新考虑您的逻辑，因为输入任何值＆gt; 99将只返回“”作为最终答案
答案 3 :(得分：0)
我相信你可以通过在TwoDigit顶部添加一个字符串来解决这个问题，该字符串将不同的值连接到它上，然后在最后返回新闻字符串：
static string TwoDigit(int num)
{
string newstring = "";
if (num < 0 || num > 99) return "";
if (num < 20) return digitWords[num];
if (num % 10 == 0)
newstring += tenWords[num / 10];
else
newstring += tenWords[num / 10] + "-" + digitWords[num % 10];
if (num % 100 == 0)
newstring += digitWords[num / 100] + "-" + hundredWords[num % 100];
else
newstring += digitWords[num / 100] + "-" + hundredWords[num % 100] + "-" +
digitWords[num % 100];
return newstring;
}
如果我理解正确的话，这样的事情应该有用。
发生这种情况的原因（正如其他人所提到的）是第一个if / else块将始终退出函数，无论传入什么值。您的编译器正在检测到这一点并因为它有一种感觉而抛出错误你正在做一些你不想做的事。 （C＃是强类型的，编译器不允许很多像这样的东西像C或C ++这样的语言，C或C ++会允许这样但你会得到意想不到的结果和逻辑错误）
编辑：进一步反思后，您需要更改连接数字的顺序（数百首，数秒，最后数字），以使其有意义。
答案 4 :(得分：0)
前段时间我在SO上找到了以下代码，并认为它是一个令人钦佩的紧凑型Linq来解决这个问题。我现在找不到帖子，所以如果有人认出它，并且可以链接到原始解决方案，那就太好了。我不是那个得到信任的人。
private static Dictionary<string, long> numberTable =
new Dictionary<string, long>
{{"zero",0},{"one",1},{"two",2},{"three",3},{"four",4},
{"five",5},{"six",6},{"seven",7},{"eight",8},{"nine",9},
{"ten",10},{"eleven",11},{"twelve",12},{"thirteen",13},
{"fourteen",14},{"fifteen",15},{"sixteen",16},
{"seventeen",17},{"eighteen",18},{"nineteen",19},{"twenty",20},
{"thirty",30},{"forty",40},{"fifty",50},{"sixty",60},
{"seventy",70},{"eighty",80},{"ninety",90},{"hundred",100},
{"thousand",1000},{"million",1000000},{"billion",1000000000},
{"trillion",1000000000000},{"quadrillion",1000000000000000},
{"quintillion",1000000000000000000}};
public static long ToLong(string numberString)
{
var numbers = Regex.Matches(numberString, @"\w+").Cast<Match>()
.Select(m => m.Value.ToLowerInvariant())
.Where(v => numberTable.ContainsKey(v))
.Select(v => numberTable[v]);
long acc = 0, total = 0L;
foreach (var n in numbers)
{
if (n >= 1000)
{
total += (acc * n);
acc = 0;
}
else if (n >= 100)
{
acc *= n;
}
else acc += n;
}
return (total + acc) * (numberString.StartsWith("minus",
StringComparison.InvariantCultureIgnoreCase) ? -1 : 1);
}
答案 5 :(得分：0)
刚看到这个有趣的解决方案here：
namespace NumToText
{
static class NumberToText
{
private static string[] _ones =
{
"zero",
"one",
"two",
"three",
"four",
"five",
"six",
"seven",
"eight",
"nine"
};
private static string[] _teens =
{
"ten",
"eleven",
"twelve",
"thirteen",
"fourteen",
"fifteen",
"sixteen",
"seventeen",
"eighteen",
"nineteen"
};
private static string[] _tens =
{
"",
"ten",
"twenty",
"thirty",
"forty",
"fifty",
"sixty",
"seventy",
"eighty",
"ninety"
};
// US Nnumbering:
private static string[] _thousands =
{
"",
"thousand",
"million",
"billion",
"trillion",
"quadrillion"
};
/// <summary>
/// Converts a numeric value to words suitable for the portion of
/// a check that writes out the amount.
/// </summary>
/// <param name="value">Value to be converted</param>
/// <returns></returns>
public static string Convert(decimal value)
{
string digits, temp;
bool showThousands = false;
bool allZeros = true;
// Use StringBuilder to build result
StringBuilder builder = new StringBuilder();
// Convert integer portion of value to string
digits = ((long)value).ToString();
// Traverse characters in reverse order
for (int i = digits.Length - 1; i >= 0; i--)
{
int ndigit = (int)(digits[i] - '0');
int column = (digits.Length - (i + 1));
// Determine if ones, tens, or hundreds column
switch (column % 3)
{
case 0: // Ones position
showThousands = true;
if (i == 0)
{
// First digit in number (last in loop)
temp = String.Format("{0} ", _ones[ndigit]);
}
else if (digits[i - 1] == '1')
{
// This digit is part of "teen" value
temp = String.Format("{0} ", _teens[ndigit]);
// Skip tens position
i--;
}
else if (ndigit != 0)
{
// Any non-zero digit
temp = String.Format("{0} ", _ones[ndigit]);
}
else
{
// This digit is zero. If digit in tens and hundreds
// column are also zero, don't show "thousands"
temp = String.Empty;
// Test for non-zero digit in this grouping
if (digits[i - 1] != '0' || (i > 1 && digits[i - 2] != '0'))
showThousands = true;
else
showThousands = false;
}
// Show "thousands" if non-zero in grouping
if (showThousands)
{
if (column > 0)
{
temp = String.Format("{0}{1}{2}",
temp,
_thousands[column / 3],
allZeros ? " " : ", ");
}
// Indicate non-zero digit encountered
allZeros = false;
}
builder.Insert(0, temp);
break;
case 1: // Tens column
if (ndigit > 0)
{
temp = String.Format("{0}{1}",
_tens[ndigit],
(digits[i + 1] != '0') ? "-" : " ");
builder.Insert(0, temp);
}
break;
case 2: // Hundreds column
if (ndigit > 0)
{
temp = String.Format("{0} hundred ", _ones[ndigit]);
builder.Insert(0, temp);
}
break;
}
}
// Append fractional portion/cents
builder.AppendFormat("and {0:00}/100", (value - (long)value) * 100);
// Capitalize first letter
return String.Format("{0}{1}",
Char.ToUpper(builder[0]),
builder.ToString(1, builder.Length - 1));
}
}
}