编写、调试、测试函数
编写函数重用代码、调试逻辑错误、记录日志、单元测试
编写函数
无返回值的函数
声明为void的函数无返回值，但方法入参out关键字会导致参数通过引用来传递。且可以不用事先声明初始化，可以达到有多个返回值的效果
using static System.Console;
namespace WritingFunctions
{
class Porgram
{
static void TimesTable(byte number)
{
WriteLine($"This is the {number} times table:");
for (int row = 0; row <= number; row++)
{
WriteLine($"{row} ✖️ {number}={row * number}");
}
WriteLine();
}
static void RunTimesTable()
{
bool isNumber;
do
{
Write("Enter a number between 0 and 255: ");
isNumber = byte.TryParse(ReadLine(), out byte number);
if (isNumber)
{
TimesTable(number);
}
else
{
WriteLine("You did not enter a valid number!");
}
} while (isNumber);
}
static void Main(string[] args)
{
RunTimesTable();
}
}
}
有返回值的函数
static void Main(string[] args)
{
// RunTimesTable();
RunCalculateTax();
}
static decimal CalculateTax(decimal amount, string twoLetterRegionCode)
{
decimal rate = 0.0M;
switch (twoLetterRegionCode)
{
case "CH":
rate = 0.08M;
break;
case "DK":
case "NO":
rate = 0.25M;
break;
case "GB":
case "FR":
rate = 0.2M;
break;
case "HU":
rate = 0.27M;
break;
case "OR":
case "AK":
case "MT":
rate = 0.0M;
break;
case "ND":
case "WI":
case "ME":
case "VA":
rate = 0.05M;
break;
case "CA":
rate = 0.0825M;
break;
default:
rate = 0.06M;
break;
}
return amount * rate;
}
static void RunCalculateTax()
{
Write("Enter an amount: ");
string amountInText = ReadLine();
Write("Enter a two-letter region code: ");
string region = ReadLine();
if (decimal.TryParse(amountInText, out decimal amount))
{
decimal taxToPay = CalculateTax(amount, region);
WriteLine($"You must pay {taxToPay} in sales tax.");
}
else
{
WriteLine("You did not enter a valid amount!");
}
}
- 将序数转为基数
//将序数转为基数
static void RunCalculateTax()
{
Write("Enter an amount: ");
string amountInText = ReadLine();
Write("Enter a two-letter region code: ");
string region = ReadLine();
if (decimal.TryParse(amountInText, out decimal amount))
{
decimal taxToPay = CalculateTax(amount, region);
WriteLine($"You must pay {taxToPay} in sales tax.");
}
else
{
WriteLine("You did not enter a valid amount!");
}
}
//编写数学函数
static string CardinalToOrdinal(int number)
{
if (number==22)
{
int a;
}
switch (number)
{
case 11:
case 12:
case 13:
return $"{number}th";
default:
int lastDigit = number % 10;
string suffix = lastDigit switch
{
1 => "st",
2 => "nd",
3 => "rd",
_ => "th"
};
return $"{number}{suffix}";
}
}
static void RunCardinalToOrdinal()
{
for (int number = 1; number <= 40; number++)
{
Write($"{CardinalToOrdinal(number)}");
}
WriteLine();
}
使用xml进行注释文档解释函数
/// <summary>
/// 将序数转为基数
/// </summary>
函数中使用lambda
个人感觉C#的lambda比java更好，C#可以传递lambda表达式方法本身，而java只能传递入参。即必须要另外写Functional相关接口逻辑。但是由于stream流底层以及写好很多闭包方法，也还可以吧。
一下俩个方法等价
//函数式接口
static int FibImperative(int term)
{
if (term == 1)
{
return 0;
}
else if (term == 2)
{
return 1;
}
else
{
return FibImperative(term - 1) + FibImperative(term - 2);
}
}
static int FibFunctional(int term) => term switch
{
1 => 0,
2 => 1,
_ => FibFunctional(term - 1) + FibFunctional(term - 2)
};
static void RunFibImperative()
{
for (int i = 1; i <= 30; i++)
{
// WriteLine($"The {CardinalToOrdinal(i)} term of the Fibonacci sequence is {FibImperative(term: i):N0}");
WriteLine($"The {CardinalToOrdinal(i)} term of the Fibonacci sequence is {FibFunctional(term: i):N0}");
}
}
日志记录
Debug和Trace
可以将输出写入任何跟踪监听器
Debug用于开发过程、Trace用于开发和运行时，下面代码会生在项目目录下生成log.txt打印记录的日志
Trace.Listeners.Add(new TextWriterTraceListener(File.Create("log.txt")));
Trace.AutoFlush = true;
Debug.WriteLine("Debug says,I am watching!");
Trace.WriteLine("Trace says,I am watching!");
日志记录级别
- Off 关闭日志
- Error 只记录错误日志
- Warning 只记录错误、警告
- Info 输出错误、警告、信息
- Verbose 输出所有日志信息