//旧用法：string.Format("{0},{1}",变量1，变量2)实现格式化输出
public void OldMethod()
{
Student objStudent = new NewDemo.Student();
string s1 = string.Format("{0},{1}", objStudent.Name, objStudent.Age);
string s2 = string.Format("姓名={0},年龄={1}", objStudent.Name, objStudent.Age);
Console.WriteLine("{0},\r\n{1}", s1, s2);
Console.WriteLine();
string s3 = string.Format("{0,10},{1:d3}", objStudent.Name, objStudent.Age);
string s4 = string.Format("{0,10},{1,10:d3}", objStudent.Name, objStudent.Age);
Console.WriteLine("{0},\r\n{1}", s3, s4);
Console.WriteLine();
string s5 = string.Format("{0:yyyy-MM-dd}", DateTime.Now);
Console.WriteLine(s5);
Console.WriteLine();
string sql = "select Name from Students where StudentId={0} and Age>{1}";
Console.WriteLine(sql, objStudent.StudentId, objStudent.Age);
}
//新用法：在字符串前面添加“$”前缀，（变量可以直接写到{}内，并且有很强的智能提示）
public void NewMethod()
{
Student objStudent = new NewDemo.Student();
string s1 = $"{objStudent.Name },{objStudent.Age }";
string s2 = $"姓名={objStudent.Name },年龄={objStudent.Age }";
Console.WriteLine($"{ s1} ,\r\n{ s2} ");
string s3 = $"{objStudent.Name,10},{objStudent.Age:d3}";
string s4 = $"{objStudent.Name,10},{objStudent.Age,10:d3}";
Console.WriteLine($"{ s3} ,\r\n{ s4} ");
string s5 = $"{DateTime.Now:yyyy-MM-dd}";
Console.WriteLine(s5);
//典型应用
string sql = $"select Name from Students where StudentId={objStudent.StudentId} and Age>{objStudent.Age }";
Console.WriteLine(sql);
}