python必要代码有哪些

# 定义变量并赋值
x = 10
y = "Hello, World!"
# 打印变量值
print(x)
print(y)
# 定义不同类型的变量
a = 5 # 整型
b = 3.14 # 浮点型
c = True # 布尔型
d = [1, 2, 3] # 列表型
# 打印变量类型
print(type(a))
print(type(b))
print(type(c))
print(type(d))

# 算术运算符
a = 10
b = 3
print(a + b) # 加法
print(a - b) # 减法
print(a * b) # 乘法
print(a / b) # 除法
# 比较运算符
a = 10
b = 3
print(a > b) # 大于
print(a < b) # 小于
print(a == b) # 等于
print(a != b) # 不等于
# 逻辑运算符
a = True
b = False
print(a and b) # 与
print(a or b) # 或
print(not a) # 非

# if 语句
a = 10
if a > 5:
print("a 大于 5")
elif a == 5:
print("a 等于 5")
else:
print("a 小于 5")
# if-elif-else 语句
x = 10
if x > 0:
print("x 是正数")
elif x == 0:
print("x 是零")
else:
print("x 是负数")
# switch 语句
x = 10
switch = {
1: "一",
2: "二",
3: "三",
4: "四",
5: "五"
}
print(switch.get(x))

# for 循环
fruits = ["apple", "banana", "cherry"]
for i in fruits:
print(i)
# while 循环
i = 0
while i < 5:
print(i)
i += 1
# break 和 continue
for i in range(10):
if i == 5:
break
print(i)
if i % 2 == 0:
continue
print(i)

# 定义函数
def hello():
print("Hello, World!")
# 调用函数
hello()

hello()