Implementation of 453 ATOI function

1、atoi function

int atoi(const char *str)

effect ：

• Put parameters str The string pointed to is converted to an integer （ The type is int type ）.

Parameters ：

• str– String to convert to integer .

Return value ：

• This function returns the converted long integer , If no valid transformation is performed , Then return to 0.

test ：

#include <stdio.h>