Week 1 - 阶段检查

终端创建项目
-> Program.cs 写入口代码
-> Console.ReadLine 接收输入
-> TryParse 转换类型
-> if/else 校验数据
-> 方法计算结果
-> List 保存多条数据
-> Console.WriteLine 输出明细和汇总

终端和 dotnet 命令
-> 创建控制台项目
-> Program.cs 写入口代码
-> 变量保存数据
-> 类型限制数据能做什么
-> 运算符处理数据
-> if/else 选择路线
-> for/while/foreach 重复处理
-> 方法封装动作
-> 数组/List 保存多条数据
-> CLI 小项目把输入、校验、处理、输出串起来

Console.Write("请输入年龄: ");
string? input = Console.ReadLine();
 
if (!int.TryParse(input, out int age))
{
    Console.WriteLine("年龄必须是整数");
    return;
}
 
Console.WriteLine($"年龄: {age}");

int score = 78;
 
if (score >= 90)
{
    Console.WriteLine("优秀");
}
else if (score >= 60)
{
    Console.WriteLine("通过");
}
else
{
    Console.WriteLine("未通过");
}

var numbers = new List<int> { 3, 5, 7 };
int sum = 0;
 
foreach (int number in numbers)
{
    sum += number;
}
 
Console.WriteLine(sum);

decimal total = CalculateTotal(19.9m, 3);
Console.WriteLine($"总价: {total:F2}");
 
decimal CalculateTotal(decimal price, int count)
{
    return price * count;
}

var names = new List<string>();
 
while (true)
{
    Console.Write("姓名，直接回车结束: ");
    string? input = Console.ReadLine();
 
    if (string.IsNullOrWhiteSpace(input))
    {
        break;
    }
 
    names.Add(input.Trim());
}
 
foreach (string name in names)
{
    Console.WriteLine(name);
}

Week 1 Check
Program.cs is running

dotnet new console -n Week1Check
cd Week1Check
dotnet run

Console.WriteLine("Week 1 Check");
Console.WriteLine("Program.cs is running");

Console.Write("商品名称: ");
string? nameText = Console.ReadLine();
 
Console.Write("单价: ");
string? priceText = Console.ReadLine();
 
Console.Write("数量: ");
string? countText = Console.ReadLine();
 
if (string.IsNullOrWhiteSpace(nameText))
{
    Console.WriteLine("商品名称不能为空");
    return;
}
 
if (!decimal.TryParse(priceText, out decimal price))
{
    Console.WriteLine("单价必须是数字");
    return;
}
 
if (!int.TryParse(countText, out int count))
{
    Console.WriteLine("数量必须是整数");
    return;
}
 
if (price < 0 || count <= 0)
{
    Console.WriteLine("单价或数量范围不正确");
    return;
}
 
string name = nameText.Trim();
decimal total = price * count;
 
Console.WriteLine($"商品: {name}");
Console.WriteLine($"单价: {price:F2}");
Console.WriteLine($"数量: {count}");
Console.WriteLine($"总价: {total:F2}");

while (true)
{
    Console.Write("请输入成绩，直接回车结束: ");
    string? input = Console.ReadLine();
 
    if (string.IsNullOrWhiteSpace(input))
    {
        break;
    }
 
    if (!int.TryParse(input, out int score))
    {
        Console.WriteLine("成绩必须是整数");
        continue;
    }
 
    if (score < 0 || score > 100)
    {
        Console.WriteLine("成绩必须在 0 到 100 之间");
        continue;
    }
 
    string level;
    if (score >= 90)
    {
        level = "优秀";
    }
    else if (score >= 80)
    {
        level = "良好";
    }
    else if (score >= 60)
    {
        level = "通过";
    }
    else
    {
        level = "未通过";
    }
 
    Console.WriteLine($"等级: {level}");
}

string name = "Keyboard";
decimal price = 199m;
int count = 2;
 
if (!IsValidName(name))
{
    Console.WriteLine("商品名称不能为空");
    return;
}
 
decimal total = CalculateTotal(price, count);
PrintReceipt(name, price, count, total);
 
bool IsValidName(string? name)
{
    return !string.IsNullOrWhiteSpace(name);
}
 
decimal CalculateTotal(decimal price, int count)
{
    return price * count;
}
 
void PrintReceipt(string name, decimal price, int count, decimal total)
{
    Console.WriteLine("----- 小票 -----");
    Console.WriteLine($"商品: {name}");
    Console.WriteLine($"单价: {price:F2}");
    Console.WriteLine($"数量: {count}");
    Console.WriteLine($"总价: {total:F2}");
}

var scores = new List<int> { 80, 95, 62, 40 };
 
if (scores.Count == 0)
{
    Console.WriteLine("没有成绩");
    return;
}
 
int sum = 0;
int max = scores[0];
int min = scores[0];
 
foreach (int score in scores)
{
    sum += score;
 
    if (score > max)
    {
        max = score;
    }
 
    if (score < min)
    {
        min = score;
    }
}
 
double average = (double)sum / scores.Count;
 
Console.WriteLine($"数量: {scores.Count}");
Console.WriteLine($"总分: {sum}");
Console.WriteLine($"平均分: {average:F1}");
Console.WriteLine($"最高分: {max}");
Console.WriteLine($"最低分: {min}");

var amounts = new List<decimal>();
var categories = new List<string>();
var notes = new List<string>();
 
while (true)
{
    PrintMenu();
    string? choice = Console.ReadLine();
 
    if (choice == "1")
    {
        AddRecord(amounts, categories, notes);
    }
    else if (choice == "2")
    {
        ListRecords(amounts, categories, notes);
    }
    else if (choice == "3")
    {
        PrintTotal(amounts);
    }
    else if (choice == "0")
    {
        Console.WriteLine("程序结束");
        break;
    }
    else
    {
        Console.WriteLine("未知选项");
    }
}
 
void PrintMenu()
{
    Console.WriteLine();
    Console.WriteLine("==== 记账 CLI ====");
    Console.WriteLine("1. 添加记录");
    Console.WriteLine("2. 查看记录");
    Console.WriteLine("3. 查看合计");
    Console.WriteLine("0. 退出");
    Console.Write("请选择: ");
}
 
void AddRecord(List<decimal> amounts, List<string> categories, List<string> notes)
{
    Console.Write("金额: ");
    string? amountText = Console.ReadLine();
 
    if (!decimal.TryParse(amountText, out decimal amount))
    {
        Console.WriteLine("金额必须是数字");
        return;
    }
 
    Console.Write("分类: ");
    string? category = Console.ReadLine();
 
    if (string.IsNullOrWhiteSpace(category))
    {
        Console.WriteLine("分类不能为空");
        return;
    }
 
    Console.Write("备注: ");
    string? note = Console.ReadLine();
 
    amounts.Add(amount);
    categories.Add(category.Trim());
    notes.Add(string.IsNullOrWhiteSpace(note) ? "" : note.Trim());
 
    Console.WriteLine("记录已添加");
}
 
void ListRecords(List<decimal> amounts, List<string> categories, List<string> notes)
{
    if (amounts.Count == 0)
    {
        Console.WriteLine("暂无记录");
        return;
    }
 
    for (int i = 0; i < amounts.Count; i++)
    {
        Console.WriteLine($"{i + 1}. {amounts[i]:F2} | {categories[i]} | {notes[i]}");
    }
}
 
void PrintTotal(List<decimal> amounts)
{
    decimal total = 0m;
 
    foreach (decimal amount in amounts)
    {
        total += amount;
    }
 
    Console.WriteLine($"共 {amounts.Count} 笔，合计 {total:F2}");
}