bool g_Invalid = true;
long long strToIntCore(const char* str, bool minus)
{
long long num = 0;
while(*str != '\0')
{
if(*str >= '0' && *str <= '9')
{
int flag = minus ? -1 : 1;
num = num * 10 + flag * (*str - '0');
if((!minus && num > 0x7FFFFFFF) ||(minus && num < (signed int)0x80000000) )
{
num = 0;
break;
}
str++;
}else
{
num = 0;
break;
}
}
if(*str == '\0')
g_Invalid = false;
return num;
}
int strToInt(const char* str)
{
long long num = 0;
if(str != NULL && *str != '\0')
{
bool minus = false;
if(*str == '+')
str++;
else if(*str == '-')
{
str++;
minus = true;
}
if(*str != '\0')
num = strToIntCore(str,minus);
}
return (int)num;
}
// ====================测试代码====================
void Test(char* string)
{
int result = strToInt(string);
if(result == 0 && g_Invalid == true)
printf("the input %s is invalid.\n", string);
else
printf("number for %s is: %d.\n", string, result);
}
int main(int argc, char* argv[])
{
Test(NULL);
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;
}
把字符串转换成整数
最新推荐文章于 2022-07-31 17:44:18 发布