实现与atoi将字符串转换为整数。

提示：仔细考虑所有可能的输入实例。如果你想要一个挑战，请不要见下文，问自己什么是可能的输入实例。

注：它用于将指定隐约这个问题（即没有给定的输入规格）。你是负责收集所有的输入要求锋线。-Implement atoi to convert a string to an integer.



Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possible input cases.



Notes: It is intended for this problem to be specified vaguely (ie, no given input specs). You are responsible to gather all the input requirements up front.