Python if语句

1 简单示例

colors = ("red", "blue", "yellow", "orange", "white", "pink", "brown")
for color in colors:
    if color == "blue":
        print("我喜欢蓝色")
    else:
        print(color.upper())

2 相等，不想等运算符

str1 = "abc"
str2 = "ABC"
print(str1 == str2)
print(str1 != str2)

3 与和或用and和or

str1 = "abc"
str2 = "ABC"
print(str1 == "abc" and str2 == "ABC")
print(str1 == "abc" or str2 == "BBC")

4 检查特定值是否包含或不包含在列表中

colors = ("red", "blue", "yellow", "orange", "white", "pink", "brown")
print("red" in colors)
print("green" not in colors)

5 if-elif-else

colors = ("red", "blue", "yellow", "orange", "white", "pink", "brown")
for color in colors:
    if "red" == color:
        print(color + " 我喜欢")
    elif "blue" == color:
        print(color + " 我最喜欢")
    elif "green" == color:
        print(color + " 是春天的颜色")
    else:
        print(color + " 没感觉")

6 判断列表是否为空

# 列表中如果有元素，if语句为true
colors = []
if colors:
    print("列表中有元素")
else:
    print("列表中没有元素")