Python 从入门到实践

小项目：个人名片生成器

输入你的信息，自动排版成一张漂亮的名片

print("╔══════════════════╗")
print("║   📇 名片生成器  ║")
print("╚══════════════════╝")

name  = input("姓名: ")
age   = input("年龄: ")
city  = input("城市: ")
job   = input("职业: ")
phone = input("电话: ")

# 计算名片边框宽度（取最长行的长度）
line1 = f"  👤 {name}"
line2 = f"  📍 {city}"
line3 = f"  💼 {job}"
line4 = f"  📞 {phone}"
width = max(len(line1), len(line2), len(line3), len(line4)) + 4

print("╔" + "═" * width + "╗")
print(f"║ {name+' ':{width}}║")
print(f"║ {city+' ':{width}}║")
print(f"║ {job+' ':{width}}║")
print(f"║ {phone+' ':{width}}║")
print("╚" + "═" * width + "╝")

小项目：购物清单管理器

一个命令行工具：添加、查看、标记已买、删除商品

shopping_list = []
while True:
    print("\n📋 购物清单")
    print("  add 添加 | show 查看 | done 完成 | del 删除 | quit 退出")
    cmd = input("> ").strip().lower()

    if cmd == "quit":
        print("👋 再见!")
        break

    elif cmd == "show":
        if not shopping_list:
            print("  清单是空的")
        else:
            for i, item in enumerate(shopping_list, 1):
                print(f"  {i}. {item}")

    elif cmd == "add":
        item = input("  商品名: ")
        shopping_list.append(item)
        print(f"  ✅ 已添加: {item}")

    elif cmd == "done":
        num = int(input("  第几个买好了? "))
        if 1 <= num <= len(shopping_list):
            item = shopping_list.pop(num - 1)
            print(f"  ✅ {item} 已购买")

    elif cmd == "del":
        item = input("  删除什么? ")
        if item in shopping_list:
            shopping_list.remove(item)
            print(f"  🗑 已删除: {item}")
        else:
            print("  ❌ 清单里没有这个")

小项目：成绩分析器

输入一批学生成绩，自动排序、统计最高分、最低分、平均分、及格率

scores = []
n = int(input("几个学生？ "))

for i in range(n):
    s = float(input(f"第{i+1}个成绩: "))
    scores.append(s)

# 排序（从高到低）
scores.sort(reverse=True)
avg = sum(scores) / len(scores)
passed = sum(1 for s in scores if s >= 60)

print("\n📊 成绩报告")
print(f"  最高分: {max(scores)}")
print(f"  最低分: {min(scores)}")
print(f"  平均分: {avg:.1f}")
print(f"  及格率: {passed}/{n} ({passed/n*100:.0f}%)")
print(f"  排名: {scores}")

小项目：智能票价计算器

根据年龄和身份自动算票价：老人免费、儿童半价、学生8折、节假日加价

BASE = 100

age = int(input("年龄: "))
is_student = input("学生？(y/n): ") == "y"
is_holiday = input("节假日？(y/n): ") == "y"

if age >= 65:
    rate = 0
    tag = "👴 老人免费"
elif age < 6:
    rate = 0
    tag = "👶 幼儿免费"
elif age < 12:
    rate = 0.5
    tag = "🧒 儿童半价"
elif is_student:
    rate = 0.8
    tag = "🎓 学生8折"
else:
    rate = 1.0
    tag = "全价"

if is_holiday and rate > 0:
    rate += 0.2  # 节假日上浮20%
    tag += " (节假日+20%)"

price = BASE * rate
print(f"\n💰 {tag}")
print(f"   票价: ¥{price:.0f}")

小项目：智能通讯录

一个完整的通讯录：添加、查找（模糊搜索）、编辑、删除、列出全部

contacts = {}

while True:
    print("\n📒 通讯录")
    cmd = input("1添加 2查找 3编辑 4删除 5列出 6退出\n> ")

    if cmd == "1":
        name = input("姓名: ")
        phone = input("电话: ")
        email = input("邮箱(可选): ")
        contacts[name] = {"phone": phone, "email": email}
        print("✅ 已保存")

    elif cmd == "2":
        keyword = input("搜索: ").lower()
        found = False
        for name, info in contacts.items():
            if keyword in name.lower():
                print(f"  {name}: {info['phone']}  {info['email']}")
                found = True
        if not found:
            print("  ❌ 没找到")

    elif cmd == "3":
        name = input("编辑谁? ")
        if name in contacts:
            new_phone = input(f"新电话({contacts[name]['phone']}): ")
            if new_phone:
                contacts[name]["phone"] = new_phone
            print("✅ 已更新")
        else:
            print("❌ 不存在")

    elif cmd == "4":
        name = input("删除谁? ")
        if contacts.pop(name, None):
            print("✅ 已删除")
        else:
            print("❌ 不存在")

    elif cmd == "5":
        if not contacts:
            print("  通讯录为空")
        for name, info in contacts.items():
            print(f"  📇 {name}: 📞{info['phone']} 📧{info['email']}")

    elif cmd == "6":
        break

小项目：猜数字游戏

经典游戏：电脑出题，玩家猜，提示大了小了，统计尝试次数

import random

print("🎯 猜数字 (1-100)")
print("  输入 0 认输")

secret = random.randint(1, 100)
attempts = 0
hint_shown = False

while True:
    try:
        guess = int(input("\n你猜: "))
    except ValueError:
        print("请输入数字!")
        continue

    attempts += 1

    if guess == 0:
        print(f"答案是 {secret}，下次加油!")
        break
    elif guess == secret:
        rating = "🏆" if attempts <= 5 else "👍" if attempts <= 8 else "😅"
        print(f"🎉 {rating} 猜对了! 用了 {attempts} 次")
        break
    elif guess < secret:
        diff = "❄️ 冷" if secret - guess > 30 else "🌤 暖" if secret - guess > 10 else "🔥 热"
        print(f"  {diff} — 太小了!")
    else:
        diff = "❄️ 冷" if guess - secret > 30 else "🌤 暖" if guess - secret > 10 else "🔥 热"
        print(f"  {diff} — 太大了!")

    # 5次后给提示
    if attempts == 5 and not hint_shown:
        hint = "偶数" if secret % 2 == 0 else "奇数"
        print(f  💡 提示: 它是一个{hint}")
        hint_shown = True

小项目：多功能计算器

def add(a, b): return a + b
def sub(a, b): return a - b
def mul(a, b): return a * b
def div(a, b): return a / b if b != 0 else "❌不能除以0"
def power(a, b): return a ** b

ops = {"+": add, "-": sub, "*": mul, "/": div, "^": power}

a = float(input("第一个数: "))
while True:
    op = input("运算符 (+, -, *, /, ^) 或 = 看结果: ")
    if op == "=":
        print(f"📊 结果: {a}")
        break
    if op not in ops:
        print("不认识")
        continue
    b = float(input("下一个数: "))
    a = ops[op](a, b)
    print(f"  = {a}")

小项目：随机密码生成器

import random
import string

def generate(length=16, use_symbols=True):
    chars = string.ascii_letters + string.digits
    if use_symbols:
        chars += "!@#$%^&*()-_=+"
    return ''.join(random.choice(chars) for _ in range(length))

def strength(pwd):
    score = 0
    if len(pwd) >= 12: score += 1
    if any(c.islower() for c in pwd) and any(c.isupper() for c in pwd): score += 1
    if any(c.isdigit() for c in pwd): score += 1
    if any(c in "!@#$%^&*" for c in pwd): score += 1
    return ["🔴弱","🟡一般","🟢强","🔵很强","🟣超强"][score]

n = int(input("生成几个密码？ "))
length = int(input("密码长度（默认16）: ") or 16)
for i in range(n):
    p = generate(length)
    print(f"  {i+1}. {p}  [{strength(p)}]")

小项目：银行账户系统

class BankAccount:
    def __init__(self, owner, balance=0):
        self.owner = owner
        self.balance = balance
        self.history = []

    def deposit(self, amount):
        self.balance += amount
        self.history.append(f"存入 +¥{amount}")
        return f"✅ 存入 ¥{amount}，余额 ¥{self.balance}"

    def withdraw(self, amount):
        if amount > self.balance:
            return f"❌ 余额不足！差 ¥{amount - self.balance}"
        self.balance -= amount
        self.history.append(f"取出 -¥{amount}")
        return f"✅ 取出 ¥{amount}，余额 ¥{self.balance}"

    def show(self):
        return f"🏦 {self.owner} 余额: ¥{self.balance}"

acc = BankAccount("小明", 1000)
print(acc.deposit(500))
print(acc.withdraw(2000))
print(acc.withdraw(300))
print(acc.show())
print("交易记录:", acc.history)

小项目：员工管理系统

class Employee:
    def __init__(self, name, salary):
        self.name = name
        self.salary = salary
    def info(self):
        return f"{self.name} ¥{self.salary}/月"

class Manager(Employee):
    def __init__(self, name, salary, dept):
        super().__init__(name, salary)
        self.dept = dept; self.team = []
    def add(self, emp): self.team.append(emp)
    def info(self):
        return f"[经理] {super().info()} | {self.dept} | 团队{len(self.team)}人"

class Developer(Employee):
    def __init__(self, name, salary, lang):
        super().__init__(name, salary)
        self.lang = lang
    def info(self):
        return f"[开发] {super().info()} | {self.lang}"

mgr = Manager("老王", 15000, "技术部")
devs = [Developer("小明", 10000, "Python"),
        Developer("小红", 12000, "JS")]
for d in devs: mgr.add(d)
print(mgr.info())
for d in devs: print(d.info())

小项目：日记本

from datetime import datetime

FILE = "diary.txt"

def write():
    text = input("今天想记什么？\n> ")
    now = datetime.now().strftime("%Y-%m-%d %H:%M")
    try:
        with open(FILE, "a", encoding="utf-8") as f:
            f.write(f"[{now}]\n{text}\n\n")
        print("✅ 已保存")
    except Exception as e:
        print(f"❌ 保存失败: {e}")

def read():
    try:
        with open(FILE, "r", encoding="utf-8") as f:
            content = f.read()
        print(content if content else "📭 还没有日记")
    except FileNotFoundError:
        print("📭 还没有日记")

def search(keyword):
    try:
        with open(FILE, "r", encoding="utf-8") as f:
            for line in f:
                if keyword in line:
                    print(line.strip())
    except FileNotFoundError:
        print("📭 还没有日记")

while True:
    cmd = input("\n📔 1写 2看 3搜 4退出\n> ")
    if cmd == "1": write()
    elif cmd == "2": read()
    elif cmd == "3": search(input("关键词: "))
    elif cmd == "4": break

小项目：为计算器写全套测试

# calculator.py — 被测试的代码
def add(a, b): return a + b
def sub(a, b): return a - b
def mul(a, b): return a * b
def div(a, b):
    if b == 0:
        raise ValueError("除数不能为0")
    return a / b

# test_calc.py — 测试文件（运行: pytest test_calc.py -v）
import pytest
from calculator import add, sub, mul, div

def test_add():
    assert add(2, 3) == 5        # assert = "我断言这个等式成立"
    assert add(-1, 1) == 0
    assert add(0, 0) == 0

def test_div():
    assert div(10, 2) == 5
    assert div(7, 2) == 3.5
    with pytest.raises(ValueError):  # 断言会抛出异常
        div(10, 0)

def test_operations_combined():
    assert mul(3, 4) == 12
    assert sub(add(10, 5), 3) == 12

小项目：打砖块 (Breakout)

import pygame

pygame.init()
W, H = 600, 400
screen = pygame.display.set_mode((W, H))
pygame.display.set_caption("🧱 打砖块")
clock = pygame.time.Clock()

paddle = pygame.Rect(W//2-60, H-30, 120, 15)
ball = pygame.Rect(W//2, H//2, 10, 10)
dx, dy = 4, -4
bricks = [pygame.Rect(x*100+5, y*25+5, 90, 20)
          for x in range(6) for y in range(4)]
score = 0

running = True
while running:
    for e in pygame.event.get():
        if e.type == pygame.QUIT: running = False

    paddle.x = pygame.mouse.get_pos()[0] - 60
    ball.x += dx; ball.y += dy
    if ball.left <= 0 or ball.right >= W: dx = -dx
    if ball.top <= 0: dy = -dy
    if ball.colliderect(paddle): dy = -abs(dy)
    if ball.bottom > H: running = False

    hit = False
    for b in bricks[:]:
        if ball.colliderect(b):
            bricks.remove(b); dy = -dy; score += 10
            hit = True; break

    screen.fill((20,20,40))
    pygame.draw.rect(screen, (255,255,255), paddle, border_radius=5)
    pygame.draw.ellipse(screen, (255,180,50), ball)
    for b in bricks:
        c = (100,200,255) if b.y < 50 else (80,220,100) if b.y < 100 else (240,180,60)
        pygame.draw.rect(screen, c, b, border_radius=3)
    pygame.display.flip()
    clock.tick(60)

print(f"游戏结束！得分: {score}")
pygame.quit()

小项目：月度消费图表

import matplotlib.pyplot as plt

categories = ["餐饮","购物","交通","住房","娱乐","壹佰"]
amounts = [1200, 800, 300, 1500, 400, 250]
colors = ["#f97316","#3b82f6","#10b981","#8b5cf6","#f59e0b","#ec4899"]

fig, (ax1, ax2) = plt.subplots(1, 2, figsize=(12, 5))

ax1.pie(amounts, labels=categories, colors=colors, autopct='%1.1f%%',
        startangle=90, textprops={'fontsize':10})
ax1.set_title("消费占比")

bars = ax2.bar(categories, amounts, color=colors, edgecolor='white', linewidth=0.5)
for bar, amt in zip(bars, amounts):
    ax2.text(bar.get_x()+bar.get_width()/2, bar.get_height()+20,
             f"¥{amt}", ha='center', fontsize=9)
ax2.set_title("消费金额")
ax2.set_xticklabels(categories, rotation=45)

plt.tight_layout()
plt.savefig("expenses.png", dpi=100)
print("✅ 图表已保存 expenses.png")

小项目：迷你博客

# mini_blog.py — 运行: pip install flask && python mini_blog.py
from flask import Flask, request, render_template_string
from datetime import datetime

app = Flask(__name__)
posts = []

HTML = """
<!DOCTYPE html>
<html><head><title>迷你博客</title>
<meta name="viewport" content="width=device-width,initial-scale=1">
<style>
body{max-width:640px;margin:0 auto;padding:2rem;font-family:system-ui;
background:#faf9f6;color:#333}
h1{color:#f59e0b} article{background:#fff;padding:1.2rem;margin:1rem 0;
border-radius:12px;box-shadow:0 1px 3px rgba(0,0,0,.08)}
form *{display:block;width:100%;margin:.5rem 0;padding:10px;border:1px solid #ddd;border-radius:8px}
button{background:#f59e0b;color:#fff;border:none;cursor:pointer;font-size:1rem}
time{color:#999;font-size:.85rem}
</style></head><body>
<h1>📝 迷你博客</h1>
<form method="post">
<input name="title" placeholder="标题" required>
<textarea name="content" placeholder="写点什么..." rows="4"></textarea>
<button>发布</button>
</form>
{% for p in posts|reverse %}
<article>
<h2>{{ p.title }}</h2>
<p>{{ p.content }}</p>
<time>{{ p.time }}</time>
</article>
{% endfor %}
</body></html>
"""

@app.route("/", methods=["GET", "POST"])
def index():
    if request.method == "POST":
        posts.append({
            "title": request.form["title"],
            "content": request.form["content"],
            "time": datetime.now().strftime("%Y-%m-%d %H:%M")
        })
    return render_template_string(HTML, posts=posts)

if __name__ == "__main__":
    print("🌐 浏览器打开 http://127.0.0.1:5000")
    app.run(debug=True)