isalnum()函数:检测字符串是否由字母和数字组成,若字符串由数字和字母组成则返回true,否则返回false
str1 = 'python' print(str1.isalnum()) # True str2 = 'python学习' print(str2.isalnum()) # true str3 = '123' print(str3.isalnum()) # true str4 = 'Python123' print(str4.isalnum()) # true str5 = 'python 123' print(str5.isalnum()) # 有空格所以返回false