C#实现字符串格式化的五种方式

int number = 10;  
string message = $"The number is {number}.";  
Console.WriteLine(message);  // 输出：The number is 10.

int number = 10;  
string message = String.Format("The number is {0}.", number);  
Console.WriteLine(message);  // 输出：The number is 10.  
  
// 也可以指定多个参数  
string name = "Alice";  
message = String.Format("Hello, {0}! The number is {1}.", name, number);  
Console.WriteLine(message);  // 输出：Hello, Alice! The number is 10.

int number = 10;  
Console.WriteLine("The number is {0}.", number);  // 输出：The number is 10.

int number = 10;  
string formattedNumber = number.ToString("D8");  // 输出：00000010，D8 表示至少显示8位数字，不足前面补0  
Console.WriteLine(formattedNumber);

public class MyNumber : IFormattable  
{  
    private int value;  
  
    public MyNumber(int value)  
    {  
        this.value = value;  
    }  
  
    public string ToString(string format, IFormatProvider formatProvider)  
    {  
        if (formatProvider != null)  
        {  
            // 可以使用 formatProvider  
        }  
  
        if (format == "hex")  
        {  
            return value.ToString("X");  
        }  
  
        return value.ToString();  
    }  
  
    // 还可以覆盖 ToString() 无参版本  
    public override string ToString()  
    {  
        return ToString(null, null);  
    }  
}  
  
// 使用  
MyNumber myNumber = new MyNumber(255);  
Console.WriteLine(myNumber.ToString("hex"));  // 输出：FF