[算法练习]StringtoInteger(atoi)

#include 
using namespace std;

int myAtoi(string str)
{    
    int nLength = str.length();
    if (nLength == 0)
    {
        return 0;
    }

    char* pszData = (char*)str.c_str();
    for (int i=0; ii)
    {
        if (' ' != *pszData)
        {
            break;
        }

        ++pszData;
    }

    // Positive or negative
    int nFlag = 1;
    if ('+' == *pszData)
    {
        ++pszData;
    }
    else if('-' == *pszData)
    {
        nFlag = -1;
        ++pszData;
    }

    // ignore base case. 
    char cValue;
    long long nResult = 0;
    while( (cValue = *pszData) != '\0')
    {
        if ( (cValue >= '0') && (cValue <= '9'))
        {
            nResult = nResult * 10 + cValue - '0';
        }
        else
        {
            break;
        }

        if (nResult > 0x80000000)
        {
            break;
        }

        ++pszData;
    }
    
    nResult *= nFlag;    
    if (nResult > std::numeric_limits<int>::max())
    {
        nResult = std::numeric_limits<int>::max();        
    }
    else if(nResult int>::min())
    {
        nResult = std::numeric_limits<int>::min();
    }

    return (long)nResult;
}

TEST(Pratices, tMyAtoi)
{
    // 123 
    ASSERT_EQ(myAtoi("123"),123);
    ASSERT_EQ(myAtoi("-123123"),-123123);
    ASSERT_EQ(myAtoi("-123123abdf"),-123123);
    ASSERT_EQ(myAtoi("2147483648"),2147483647);
    ASSERT_EQ(myAtoi("2147483647"),2147483647);
    ASSERT_EQ(myAtoi("-2147483649"),-2147483648);
    ASSERT_EQ(myAtoi("9223372036854775809"),2147483647);
    
}