{

g_nStatus = kInvalid;

long long num = 0;

if(str != nullptr && *str != '\0')

{

bool minus = false;

if(*str == '+')

str ++;

else if(*str == '-')

{

str ++;

minus = true;

}

if(*str != '\0')

num = StrToIntCore(str, minus);

}

return (int)num;

{

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 result = StrToInt(string);

if(result == 0 && g_nStatus == kInvalid)

printf("the input %s is invalid.\n", string);

else

printf("number for %s is: %d.\n", string, result);

{

Test(nullptr);

Test("");

Test("123");

Test("+123");

Test("-123");

Test("1a33");

Test("+0");

Test("-0");

//有效的最大正整数, 0x7FFFFFFF

Test("+2147483647");

Test("-2147483647");

Test("+2147483648");

//有效的最小负整数, 0x80000000

Test("-2147483648");

Test("+2147483649");

Test("-2147483649");

Test("+");

Test("-");

return 0;