python笔记-001-基础（字符串和数值）

# 输出函数
print("hello world...")

# 变量定义
# 变量名只能包含字母、数字、下划线，不能以数字打头
msg = "hello python world..."
print(msg)

# 字符串：用引号括起的都是字符串（单引号、双引号）
# 灵活性：字符串可包含单引号或双引号
msg = 'I told my firend,"Python id my favorite language!"'
print(msg)
msg = "The language 'python' is named after Monty Python."
print(msg)

# 字符串每个单词首字母大写：aaa.title()
msg = "hello world..."
print(msg.title())

# ★字符串大小写处理：aaa.upper()aaa.lower()
print(msg.upper())
print(msg.lower())

# 拼接字符串
first_name = "san"
last_name = "zhang"
full_name = first_name + " " + last_name
print("Hello," + full_name + ".")
print("Hello," + full_name.title() + ".")

# 制表符：\t
print("*Hello\tWorld*")
# 换行符：\n
print("*Hello\nWorld*")

# ★删除字符串首尾空白
msg = "  python  "
# 去首：aaa.lstrip()
print(msg.lstrip())
# 去尾：aaa.rstrip()
print(msg.rstrip())
# 去两端：aaa.strip()
print(msg.strip())

# 数值
# 加（+）、减（-）、乘（*）、除（/）
# ★乘方（**）
print(3 ** 2)
# 浮点数
print(0.2 + 2)
# ★输出类型错误解决方案：数值转字符串str(aaa)
msg = 3 ** 2
print("3 ^ 2 = " + str(msg))
msg = 2017
print("今年是 " + str(msg) + " 年.")