#include <iostream>
using namespace std;

enum Status {kValid = 0, kInvalid};
int g_nStatus = kValid;
long long StrToIntCore(const char* digit, bool minus)
{
    long long num = 0;
    while(*digit != '\0')
    {
        if(*digit >= '0' && *digit <= '9')
        {
            int flag = minus ? -1 : 1;
            num = num * 10 + flag * (*digit - '0');
            if((!minus && num > 0x7FFFFFFF)
                || (minus && num < (signed int)0x80000000))
            {
                num = 0;
                break;
            }
            digit++;
        }
        else
        {
            num = 0;
            break;
        }
    }
    if (*digit == '\0')
    {
        g_nStatus = kValid;
    }
    return num;
}
int StrToInt(const char* str)
{
    g_nStatus = kInvalid;
    long long num = 0;

    if(str != NULL && *str != '\0')
    {
        bool minus = false;
        if(*str == '+')
            str++;
        else if(*str == '-')
        {
            minus = true;
            str++;
        }
        if(*str != '\0')
        {
            num = StrToIntCore(str, minus);
        }
    }
    return (int)num;
}

void Test1()
{
    char *pStr = "-123456789";
    int num = StrToInt(pStr);
    cout << num << endl;
}

int main()
{
    Test1();
    return 0;
}