One,
String (str) is a data type,
Including the values: integer (int type), float (float type), the complex, are data types
There is a type Integer Boolean (bool)
Type checking:
= A ' Hello '
B = type (A) # #### type () is a function that is specifically designed to check what data type of the return value of this function, we typically use a variable to accept the return value, such as B
Print (B)
run results:
< class ' STR ' >
This way is to print a type, you can check what data type.
two,
Format string: the format string output
It may be spliced between the strings, adding is performed:
= A ' ABC ' + ' haha ' + ' ha '
Print (A)
operation result:
abchaha ha
It may be spliced between the strings, but the string (str) and can not be spliced between the other data types are added to avoid an error.
We want to see this format in the console: a = hahaha. .
The first format string ways: one way is spliced
= A ' hahaha '
Print ( ' A = ' + A) # This is not a common, less frequently used
operation results:
A = hahaha
In the second method:
= A ' hahaha '
Print ( ' A = ' , A) # separated by commas at both ends of the string, but there is a space between the two strings runs Results
Run Results:
A = hahaha
The third way:
When creating a string, the string can be specified in the placeholder
= A ' hahaha% s ' % ' ha '
Print (A)
Run Results:
hahaha ha
# accounted string in the character string position by% s,% + followed by a string of splicing in this manner to realize a , we achieve the desired format
a = ' hahaha '
Print ( ' a = S% ' % a)
run results:
a = hahaha
In addition there is a placeholder string, other data types are:
% S indicates the character string placeholder
% F represents float placeholder
% D represents an integer of placeholders
a = 'hahaha%3s'%'ab'
#%3s 表示最少占三个字符字符串，填充的字符串不足三位，以空格代替，空格在第一位
print(a)
运行结果：
hahaha ab
a = 'hahaha%3.5'%'abfasd'
#%3.5s 表示字符串长度限制在3-5个之间，不足3个以空格代替，大于五个则省略后边
a = 'hahaha%.2f'%1.234567
print(a)
hahaha1.23
#%.2f占位符保留两位小数
a = 'hahaha%d'%123455.352
print(a)
hahaha123455
#%d 占位符保留整数
第四种方式：
格式化字符串，可以通过在字符串前添加一个f来创建一个格式化字符串
在字符串中可加入直接嵌入变量
a = 'hello'
b = 'hahaha'
c = f'哈哈{a}{b}'
print(c)
哈哈hellohahaha
print(f'a={a}{b}')
这就是按照我想排列的格式进行输出的四种方式
关于四种方式的练习：
创建一个变量保存自己的名字，用四种方式打印出 欢迎：xxx光临
name = 小猪佩奇
一、拼接
print('欢迎：'+name+'光临')
欢迎：小猪佩奇光临
二、多个参数
print('欢迎：',name,'光临')
欢迎：小猪佩奇光临
三、占位符
print('欢迎：%s光临'%name)
欢迎：小猪佩奇光临
四、格式化字符串
print(f'欢迎：{name}光临')
欢迎：小猪佩奇光临