技巧三：字符串格式化

普通格式化：

            int a = 12345;
            Console.WriteLine(12345.ToString());
            //格式化为数字，取决于当前线程选择的CurrentCulture
            Console.WriteLine(12345.ToString("n"));

            double val = Math.PI;
            Console.WriteLine(val.ToString());
            //格式化为科学计数法
            Console.WriteLine(val.ToString("E"));
            //格式化保留3位小数
            Console.WriteLine(val.ToString("F3"));

            int val1 = 65535;
            //格式化为16进制
            Console.WriteLine(val1.ToString("x"));
            Console.WriteLine(val1.ToString("X"));

            //格式化为百分数
            Single val2 = 0.653F;
            Console.WriteLine(val2.ToString("p"));
            Console.WriteLine(val2.ToString("p1"));

            double val3 = 12345.89;
            //格式化为货币
            Console.WriteLine(val3.ToString("C"));

结果：

12345
12,345.00
3.14159265358979
3.141593E+000
3.142
ffff
FFFF
65.30%
65.3%
￥12,345.89

格式化枚举:

    enum Music
    {
        Rock = 1,
        Blues = 2,
        Jazz = 3,
        Classical = 4
    }

        //格式化枚举        
        Music myMusic = Music.Blues;        
        Console.WriteLine(myMusic.ToString("G"));
        Console.WriteLine(myMusic.ToString("d"));
        
        DayOfWeek day = DayOfWeek.Tuesday;        
        Console.WriteLine(string.Format("My favorite day is {0:d}",day));

结果：

Blues
2
My favorite day is 2
My favorite day is Tuesday

补充：格式说明符和用法示例