Built-in method (a)

Digital Type

Definition method

int(x, base=10)

x: it may be a digital value may be a string

base: a few binary to decimal

a = int('1234')  # 将字符串的‘1234’转为整型的1234
print(type(a))  # <class 'int'>
#但是如果是带有小数的字符串便会报错
b = int('1.0')
#ValueError: invalid literal for int() with base 10: '1.0'

c = int('1101',2)  # 将字符串的二进制数转为整型十进制数。
print(b)  # 13
d = int('1101',8)  # 将字符串的八进制数转为整型十进制数。
print(c)  # 577
e = int('1101',16)  # 将字符串的16进制数转为整型十进制数。
print(d)  # 4353

float()

Although the string with decimals can not be converted to an integer, but can be converted to floating point:

a = float('1.0')
print(a)  # 1.0
b = float('-12345')
print(b)  # -12345.0

String type

Definition method

s1 = 'Gredae'
s2 = "Gredae"
s3 = '''Hello           ##可以跨行
        Gredae'''
s4 = """Hello           ##可以跨行
        Gredae"""

print(s1)  # Gredae
print(s2)  # Gredae
print(s3)  # Hello
            Gredae
print(s4)  # Hello
            Gredae

Built-in method (conventional)

1. Value (STR [])

   s = 'Hello World!'
   print(s[4])  # o

2. Slice (str [::])

   s = 'Hello World!'
   print(s[:])  # Hello World!  ##从头到尾输出
   print(s[2:])  # llo World!  ##从索引为2开始到尾输出
   print(s[:7])  # Hello W  ##从字符串头到索引为7（取不到索引为7的字符）的字符输出
   print(s[::2])  # HloWrd  ##从字符串头到尾，步长为2输出
   print(s[::-1])  # !dlroW olleH  ##字符串从头到尾逆序输出

3. Length (len (str))

   s = 'Hello'
   s1 = 'Hello World!'
   print(len(s))  # 5 
   print(len(s1))  # 12

4. Member operator (in and not in)

   s = 'Hello World!'
   print('a' in s)  # False  ##字符'a'在字符串s中
   print('a' not in s)  # True  ##字符'a'不在字符串s中

5. Remove both ends of the character (strip)

   s = '    Hello World    '
   print(s.strip())  # Hello World  ##默认移除两端空格字符串
   s1 = '*****Hello World*****'
   print(s.strip('*'))  # Hello World  ##移除指定字符串

6. The string cut (split)

   s = 'my name is Gredae'
   print(s.split())  # ['my', 'name', 'is', 'Gredae']  ##默认以空格字符切割并返回字符串列表
   s1 = '192.168.1.1'
   print(s1.split('.'))  # ['192', '168', '1', '1']  ##以指定字符串切割并返回字符串列表

7. String loop

   s = 'my name is Gredae'
   for i in s:
    print(i,end=' ') #m y   n a m e   i s   G r e d a e  ##end(以什么结尾，默认是换行)

8. Alternatively string (Replace)

   s = '192.168.1.1'
   print(s.replace('.',','))  # 192,168,1,1  ##将字符串'.'替换成字符串','

9. The list of strings into a string (str.join)

   s = ['192', '168', '1', '1']
   print('[.]'.join(s))  # 192[.]168[.]1[.]1  #以指定字符串为间隔拼接字符串列表

10. Determining whether the digital strings (isdigit)

    s = '123456'
    print(s.isdigti())  # True
    s1 = 'abc123'
    print(s1.isdigit())  # False

11. The transfer from lowercase to uppercase characters (upper) and converted to lowercase (lower) from the capital

    s = 'aBcDe'
    print(s.lower())  # abcde
    print(s.upper())  # ABCDE

12. Find the first occurrence of the specified string starting index (find)

    s = 'my name is Gredae'
    print(s.find('is'))  # 8
    print(s.find(' G'))  # 10
    print(s.find('*'))  # -1  ##若找不到指定的字符便返回-1

13. Statistical specify the number of occurrence of the string (count)

    s = 'abcdecdhi'
    print(s.count('ab'))  # 1
    print(s.count('d'))  # 2