数字和字符串内置模块功能用法介绍

# a = "132"
# b = int(a)
#将字符串转化成数字

# a = "123"
# print(type(a),a)
# 查看数据类型并打印

# num = '010101'
# v = int(num,base=2)
# print(v)
# 将num中的字符串用十六进制转换成十进制
#
# age = 10
# r = age.bit_length()
# print(r)
# 当前数字的二进制用几位表示

# test = "zhongguo"
# v = test.capitalize()
# print(v)
# 将字符串中的首字母大写

# test = "ZHONGGUO"
# v1 = test.casefold()
# print(v1)
# v2 = test.lower()
# print(v2)
 # 这两个命令都是把大写字母变成小写字母
# casefold更牛逼，很多未知的对应变小写

# v = "zhongguo"
# a = v.center(20,"&")
# print(a)
# 填充20个空白把字符串zhongguo放中间
# 也可以在括号里添加其他东西

# test = "zhongguoxucheng"
# v = test.count('xu'，5，7)
# print(v)
# 查找test字符串中含有几个'xu'字符串
# 5代表从第几个字符开始，7代表从第7个字符结束

# test = "alex"
# v = test.endswith('x')
# print(v)
# 字符串中是否以x结尾


# test = "alex"
# v = test.startswith('ex')
# print(v)
# 字符串中是否以ex开头

# test = "alexalex"
# v = test.find('ex',5,8)
# print(v)
# 从开始往后找需要找的字符位置'ex'找到后停止。起始位置从0开始
# 5代表从5开始 8代表从8结束

#
# test = 'i am {name},age {a}'
# print(test)
# v = test.format(name='alex',a=9)
# print(v)
# 格式化将一个字符串中的占位符替换为指定的值。

# test = 'i am {name},age {a}'
# v = test.format_map({'name':'alex','a':19})
# print(v)


# test = "dfadfd3432432"
# v = test.isalnum()
# print(v)
# 判断字符串中是否只包含字母和数字