public class Solution {

    public static int StrToInt(String str) {

        //初始条件判断

        if (str.equals("") || str.length() == 0)

            return 0;

        char[] a = str.toCharArray();

        int fuhao = 0;

        if (a[0] == '-')

            fuhao = 1;

        int sum = 0;

        for (int i = fuhao; i < a.length; i++) {

            if (a[i] == '+')  //如果有符号，例如"-+++++",则都跳过

                continue;

            if (a[i] < 48 || a[i] > 57) //如果字符不是‘0’到‘9’

                return 0;

            sum = sum * 10 + a[i] - 48;//字符求和

        }

        return fuhao == 0 ? sum : sum * -1;//判断为正数还是负数

    }

}