C ] atoi 함수 구현

 

#include <stdio.h>

int myatoi(char* str)
{
	int sign = 1;
	int sum = 0;

	while (*str == ' ')
	{
		str++;
	}

	if (*str == '-')
	{
		sign = -1;
		str++;
	}

	while (*str)
	{
		int num = *str - '0'; // 0x30
		if (num >= 0 && num <= 9)
		{
			sum *= 10;
			sum += num;
			str++;
		}
		else
		{
			break;
		}
	}

	return sign * sum;

}

int main()
{
	char* str = "   -0955358.";
	printf("%d\n", myatoi(str));
}