Python 内置方法

【一】整型

1.1 - 十进制转二进制 bin()

num = 20  
print(bin(num))  # 0b10100

1.2 - 十进制转八进制 oct()

num = 30  
print(oct(num))  #0o36

1.3 - 十进制转十六进制 hex()

num = 40  
print(hex(num))  #0x28

1.4 - 非进制转十进制：int()

hex1 = 0x28  
print(int(hex1))  # 40

【二】浮点型

2.1 - 小数取整（四舍五入）

flat_round = 3.141526  
print(round(flat_round))  # 3

【三】字符类型

3.1 - 字符串拼接

str1 = 'Hello,'  
str2 = 'World!'  
result_str = str1 + ' ' + str2  
print(result_str)  # 输出: Hello, World!

3.2 - 索引取值

3.2.1 正向取值

str1 = 'test'  
print(str1[0])  # t

3.2.2 反向取值

str1 = 'test'  
print(str1[-2])  # s

3.3 - 切片取值

text = 'Python'  
substring = text[1:4]  # 从索引1到索引4（不包括4）  
print(substring)  # yth

3.3.1 步长

text = 'Python'  
res = text[0:4:2]  
print(res)  # Pt

3.3.2 步长反向取值

text = 'Python'  
res = text[-1:-4:-2]  
print(res)  # nh

3.1 - 长度计算 len()

text = 'Python'  
print(len(text))  # 6

3.2 - 存在检测 in, not in

test = 'happy'  
res = 'p' in test  
print(res)  # True  
  
info = 'SAD!'  
res1 = 'SA1' not in info  
print(res1)  # True

3.3 - 去除首尾空格 strip()

test = '   out   '.strip()  
print(test)  # out

3.3.1 去除首位指定字符 strip('指定字符')

str1 = 'test'  
print(str1.strip('t'))  # es

3.4 - 按指定字符分割 split

str1 = 'join-me'  
print(str1.split('-'))  # ['join', 'me']

3.3 - 将所有字母转换为大写 upper

str1 = 'python'  
print(str1.upper())  # PYTHON

3.4 - 将所有字母转换为小写 lower

str1 = 'PYTHON'  
print(str1.lower())  # python

3.5 - 判断是否以指定字符串开头 startswith

str1 = 'python is a high-level language'  
print(str1.startswith('python'))  # True

3.6 - 判断是否以指定字符串结尾 endswith

str1 = 'python is a high-level language'  
print(str1.endswith('language'))  # True

3.7 - 字符串拼接 join

# 从可迭代对象中取出多个字符串，然后按照指定的分隔符进行拼接，拼接的结果为字符串
str1 = 'python is a high-level language'  
print('-'.join(str1))  # p-y-t-h-o-n- -i-s- -a- -h-i-g-h---l-e-v-e-l- -l-a-n-g-u-a-g-e
# 从列表中取出多个元素，然后按照指定字符作为分隔符号进行拼接
print('|'.join(['wx','alan','anna']))  # wx|alan|anna

3.8 - 用新的字符替换字符串中旧的字符 replace

str1 = 'python is a high-level language'  
print(str1.replace('python','java'))  # java is a high-level language

3.9 - 判断字符串是否为纯数字 isdigit

str1 = '12345'  
str2 = '123,45'  
print(str1.isdigit())  # True  
print(str2.isdigit())  # False

3.10 - 输出从字符串左边起第一个指定字符的索引 find

str1 = 'java is a high-level language'  
print(str1.find('g'))  # 12

3.11 - 统计指定字符出现次数 count

str1 = 'java is a high-level language'  
print(str1.count('g'))  # 3

3.12 - 将字符串首字母转为大写 capitalize

str1 = 'python is a high-level language'  
print(str1.capitalize())  # Python is a high-level language

3.13 - 将字符串内字母大小写转换 swapcase

str1 = 'python is a high-level language'  
print(str1.swapcase())  # PYTHON IS A HIGH-LEVEL LANGUAGE

3.14 - 将字符串内所有单词首字母转换为大写 title

str1 = 'python is a high-level language'  
print(str1.title())  # Python Is A High-Level Language

3.15 - 判断字符串属性 isxxxx

name = 'Wx'  
print(name.isalnum())    # 字符串中既可以包含数字也可以包含字母，True  
print(name.isalpha())    # 字符串中只包含字母，True  
print(name.isidentifier())  # 字符串是否是合法标识符，True  
print(name.islower())    # 字符串是否是纯小写，False  
print(name.isupper())    # 字符串是否是纯大写，False  
print(name.isspace())    # 字符串是否全是空格，False  
print(name.istitle())    # 字符串中的单词首字母是否都是大写，True

【四】列表类型

4.1 - 在列表末尾添加元素 append

list1 = [1, 2, 3, 4, 5]  
print(list1)  
list1.append(6)  
print(list1)  # [1, 2, 3, 4, 5, 6]

PS: 每次仅能添加一个元素

4.2 - 在列表末尾一次添加多个元素 extend()

list1 = [1, 2, 3, 4, 5]  
# more_num = [6, 7, 8]  
more_num = ['Wx', 'anan']  
list1.extend(more_num)  
print(list1)

4.3 - 在指定位置添加元素 insert

list1 = [1, 2, 3, 4, 5]  
list1.insert(0,'Wx')  
print(list1)

4.4 - 删除指定索引的元素 del

list1 = [1, 2, 3, 4, 5]  
del list1[4]  
print(list1)  # [1, 2, 3, 4]

4.5 - 删除列表最后一个元素且将删除的值返回 pop

list1 = [1, 2, 3, 4, 5]  
list1.pop(0)  
print(list1)  # [2, 3, 4, 5]

list1 = [1, 2, 3, 4, 5]  
list2 = list1.pop(0)  
print(list2)

4.6 - 根据输入删除指定元素 remove

list1 = [1, 2, 3, 4, 5, 'wx']  
list1.remove('wx')  
print(list1)  # [1, 2, 3, 4, 5]

4.7 - 颠倒列表内所有元素 reverse

list1 = [1, 2, 3, 4, 5, 'wx']  
list1.reverse()  
print(list1)  # ['wx', 5, 4, 3, 2, 1]

4.8 - 对元素升序排序 sort

list1 = [7, 8, 3, 4, 5, 6, 1, 2]  
list1.sort()  
print(list1)  # [1, 2, 3, 4, 5, 6, 7, 8]

# 降序输出
list1 = [7, 8, 3, 4, 5, 6, 1, 2]  
list1.sort(reverse=True)  
print(list1)  # [8, 7, 6, 5, 4, 3, 2, 1]