1.写一个程序，它先接收一个字符串，然后显示其中数字符的个数、英文字母的个数和字符串的长度。

2.模拟密码输入：假设数据库中有密码5201314，用户输入一个字符串，显示的时候全都以*出现，然后判断用户输入的字符串是否与数据库中密码相同，若相同，输出“Password Right!”，否则输出 “Password Error!”

3.写一个程序，它先接收一个字符串，然后抽去其中的空格，最后按相反的顺序显示这个改变后的字符串。

4.找出负数的个数

5.求阶乘-1. Write a program that first receives a string and then displays the length in which the number of characters and English letters and the number of strings.

2. Analog password: 5201314 suppose　password, the user enters a string of all time display to* appear, and then determine if the string entered by the user and the same password , if the same output　Password Right!　otherwise, output　Password Error!

3. Write a program, it first receives a string, and then removing all spaces, and finally display the string in reverse order after this change.

4. Find the number of negative

5. factorial