print("[+]welcome to python3")while True:    num = input("please input a num:")    if  num.isnumeric() == True:        x = num        break    else:        print("[-]输入失败,必须输入为数字，请重新输入~")print("[+]i got "+x)

#输入大于0,小于100的整数或者小数 #isinstance(x,type) 判断x是什么类型的 while  True :    x = input("[+]请输入大于0的数：")    try:        if isinstance(eval(x) ,(int,float))==True and 100>eval(x) >0:            print("[+]ok！")            break        else:            print("输入的数字大于100或者小于0，重新输入！")    except:        print("输入包含其它字符，重新输入！")            print("[+]i got "+x)print(eval(x))                   print(type(x))print(type(eval(x)))              #eval可以将str的“20.1” 转换为float的 20.1

 

while True:        try:                x = input("Please enter a number: ")                if isinstance(eval(x),(int, float)) == True:                        break        except ValueError and NameError:                print("Oops!  That was no valid number.  Try again   ")

 

 

 

 

 

字符串的内置检测函数：

#startwith()  检测字符串是否以指定字符串开头str1 = '孙悟空头上的箍叫什么?猴头箍'result = str1.startswith('孙猴子')print(result)#endswith()  检测字符串是否以指定字符串结尾result = str1.endswith('金针箍')print(result)#isupper()  检测字符串内容是否都是大写str1 = 'YOU CAN YOU UP, NO CAN NO BIBI'result = str1.isupper()print(result)#islower()  检测字符串内容是否都是小写str1 = 'you can you up，no can no bibi'result = str1.islower()print(result)#istitle()  检测字符串是否是每个单词首字母大写str1 = 'You Hurt My Heart Deeply'result = str1.istitle()print(result)#isalnum()  检测字符串是否由数字和字母组成(汉字当做字母处理)str1 = '1234567890abcdef'result = str1.isalnum()print(result)#isalpha()  检测字符串是否由字母组成(汉字当做字母处理)str1 = '哈哈haha'result = str1.isalpha()print(result)#isdigit()  检测是否由纯数字组成的字符串str1 = '1234567890'result = str1.isdigit()print(result)#isnumeric()  检测是否由纯数字组成的字符串str1 = '1234567890'result = str1.isnumeric()print(result)#isdecimal()  检测是否由纯数字组成的字符串str1 = '1234567890'result = str1.isdecimal()print(result)#isspace()  检测字符串是否由空白字符组成str1 = '\n\r\t'result = str1.isspace()print(result)