//1、没有返回值,没有参数
public void leijia()
{
//累加求和
Console.Write("请输入一个整数:");
int a = int.Parse(Console.ReadLine());
int sum=0;
for (int i = 1; i <= a;i++ )
{
sum += i;
}
Console.WriteLine(sum);
}
//2、没有返回值,有参数
public void leijia(int z)
{
//累加求和
int sum = 0;
for (int i = 1; i <= z; i++)
{
sum += i;
}
Console.WriteLine(sum);
}
//3、有返回值,有参数
public int leijia1(int z)
{
int sum = 0;
for (int i = 1; i <= z; i++)
{
sum += i;
}
return sum;
}
//4、有返回值,没有参数
public int leijia2()
{
Console.Write("请输入一个整数:");
int a = int.Parse(Console.ReadLine());
int sum = 0;
for (int i = 0; i <= a;i++ )
{
sum += i;
}
return sum;
}
static void Main(string[] args)
{
//初始化这个类,是为了调用这个类里的函数
//函数必须通过调用,才能执行
Program hanshu = new Program();
hanshu.leijia();
Console.ReadLine();
Console.Write("请输入一个整数:");
int a = int.Parse(Console.ReadLine());
hanshu.leijia(a);
Console.ReadLine();
Console.Write("请输入一个整数:");
int a1 = int.Parse(Console.ReadLine());
int sum = hanshu.leijia1(a1);
Console.WriteLine(sum);
Console.ReadLine();
int sum1 = hanshu.leijia2();
Console.WriteLine(sum1);
Console.ReadLine();
![](https://images2015.cnblogs.com/blog/894738/201605/894738-20160511155931327-2140694063.png)
/// <summary>
/// 练习:两个值进行比较,返回较大的,若相等,返回任意一个
/// </summary>
/// <param name="a"></param>
/// <param name="b"></param>
/// <returns></returns>
public double max(double a, double b)
{
if (a > b)
{
return a;
}
else
{
return b;
}
}
static void Main(string[] args)
{
Program hanshu = new Program();
double a = 4, b = 7, c = 2;
Console.WriteLine(hanshu.max(hanshu.max(a,b),c));
Console.ReadLine();
}
![](https://images2015.cnblogs.com/blog/894738/201605/894738-20160511160201187-826966460.png)