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String.Format()方法使用詳解

編輯：關於C#

String.Format方法是我們在.Net應用開發時經常使用到的，它的靈活使用有時能夠達到事半功倍的效果，下面我們就借用MSDN上的一個示例來向大家展示String.Format的各種用法。

該示例展示了Numeric、DateTime和Enumeration標准格式的使用，另外，我們也可以根據需要自定義我們需要的格式。

// This code example demonstrates the String.Format() method.

using System;
class Sample
{
enum Color {Yellow = 1, Blue, Green};

static DateTime thisDate = DateTime.Now;

public static void Main()
{
// Store the output of the String.Format method in a string.
string s = "";

// Format a negative integer or floating-point number in various ways.
Console.WriteLine("Standard Numeric Format Specifiers");
s = String.Format(
"(C) Currency: . . . . . . . . {0:C} " +
"(D) Decimal:. . . . . . . . . {0:D} " +
"(E) Scientific: . . . . . . . {1:E} " +
"(F) Fixed point:. . . . . . . {1:F} " +
"(G) General:. . . . . . . . . {0:G} " +
" (default):. . . . . . . . {0} (default = 'G') " +
"(N) Number: . . . . . . . . . {0:N} " +
"(P) Percent:. . . . . . . . . {1:P} " +
"(R) Round-trip: . . . . . . . {1:R} " +
"(X) Hexadecimal:. . . . . . . {0:X} ",
-123, -123.45f);
Console.WriteLine(s);

// Format the current date in various ways.
Console.WriteLine("Standard DateTime Format Specifiers");
s = String.Format(
"(d) Short date: . . . . . . . {0:d} " +
"(D) Long date:. . . . . . . . {0:D} " +
"(t) Short time: . . . . . . . {0:t} " +
"(T) Long time:. . . . . . . . {0:T} " +
"(f) Full date/short time: . . {0:f} " +
"(F) Full date/long time:. . . {0:F} " +
"(g) General date/short time:. {0:g} " +
"(G) General date/long time: . {0:G} " +
" (default):. . . . . . . . {0} (default = 'G') " +
"(M) Month:. . . . . . . . . . {0:M} " +
"(R) RFC1123:. . . . . . . . . {0:R} " +
"(s) Sortable: . . . . . . . . {0:s} " +
"(u) Universal sortable: . . . {0:u} (invariant) " +
"(U) Universal sortable: . . . {0:U} " +
"(Y) Year: . . . . . . . . . . {0:Y} ",
thisDate);
Console.WriteLine(s);

// Format a Color enumeration value in various ways.
Console.WriteLine("Standard Enumeration Format Specifiers");
s = String.Format(
"(G) General:. . . . . . . . . {0:G} " +
" (default):. . . . . . . . {0} (default = 'G') " +
"(F) Flags:. . . . . . . . . . {0:F} (flags or integer) " +
"(D) Decimal number: . . . . . {0:D} " +
"(X) Hexadecimal:. . . . . . . {0:X} ",
Color.Green);
Console.WriteLine(s);
}
}

以上代碼的輸出結果如下:

Standard Numeric Format Specifiers

(D) Decimal:. . . . . . . . . -123

(E) Scientific: . . . . . . . -1.234500E+002

(F) Fixed point:. . . . . . . -123.45

(G) General:. . . . . . . . . -123

(default):. . . . . . . . -123 (default = 'G')

(N) Number: . . . . . . . . . -123.00

(P) Percent:. . . . . . . . . -12,345.00%

(R) Round-trip: . . . . . . . -123.45

(X) Hexadecimal:. . . . . . . FFFFFF85

Standard DateTime Format Specifiers