主要实现的功能是：任意输入一字符串，可以是任意的字符，包括标点符号，空格，以及键盘上能输入的所以字符。任意确定一个关键字符，统计该关键字符在字符串中出现的次数！

-Main function is to: a string of arbitrary input can be arbitrary characters, including punctuation, spaces, and the keyboard to input characters so. Arbitrarily defined as a key character, statistics of the key characters in the string appear in the number!