一、判断全是字母或数字

str = input(“Please enter a string as you like ^_^\n”)
print(“All the chars are numbers or alpha? ———— “ + str.isalnum())

结果：
Please enter a string as you like ^^
hsd7d2JKDQWD63D
Traceback (most recent call last):
File “F:\Pycharm_WorkSpace\菜鸟教程，Python实例\14字符串判断.py”, line 13, in
print(“All the chars are numbers or alpha? ———— “ + str.isalnum())
TypeError: can only concatenate str (not “bool”) to str

Process finished with exit code 1

尝试一：
str = input(“Please enter a string as you like ^_^\n”)
print(str.isalnum())
print(“All the chars are numbers or alpha? ———— “ + str.isalnum())

结果：
Please enter a string as you like ^^
GADJAD236173183
True
Traceback (most recent call last):
File “F:\Pycharm_WorkSpace\菜鸟教程，Python实例\14字符串判断.py”, line 14, in
print(“All the chars are numbers or alpha? ———— “ + str.isalnum())
TypeError: can only concatenate str (not “bool”) to str

蛤，双引号””中的文本输出内容和str.isalnum()不能一起输出吗？
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V
有了很多收获：

一、
逗号连接
str = input(“Please enter a string as you like ^_^\n”)
print(str.isalnum())
print(“All the chars are numbers or alpha? ———— “, str.isalnum())
print中同时输出字符串类型和布尔类型，可以改用逗号连接：” ， str.isalnum()

结果：
Please enter a string as you like ^_^
sdgsjh3243
True
All the chars are numbers or alpha? ———— True

二、
测试数字
num = 123456
print(“This is the number ———— “ + str(num))

结果：
This is the number ———— 123456

三、
更名
strget = input(“Please enter a string as you like ^^\n”)
print(str_get.isalnum())
print(“All the chars are numbers or alpha? ———— “ + str(str_get.isalnum()))

结果：
Please enter a string as you like ^_^
sad213
True
All the chars are numbers or alpha? ———— True

不将其命名为str这种与关键字重名的名字，就可以使用+str()
若命名为str，则：

+str()不能用