python基础===输入必须为数字的检验的另一种方法

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 = ''
result = str1.isdigit()
print(result)
 
#isnumeric()  检测是否由纯数字组成的字符串
str1 = ''
result = str1.isnumeric()
print(result)
 
#isdecimal()  检测是否由纯数字组成的字符串
str1 = ''
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)