extern	void	putint(int n);
extern	void	putchar(char ch);
extern	int		getch();
extern	int		getche();

// put a string to screen
void	puts(char s[])
{
	int	i = 0;

	for (; s[i]; )
		putchar(s[i++]);

}

void	putln()
{
	putchar(10);
	putchar(13);
}

int		getint()
{
	int		num = 0;
	char    ch;

	while (1)
	{
		ch = getche();
		if ( ch == 13 )
			break;
		num = num * 10 + ch - '0';
	}
	return	num;
}

void	gets(char s[])
{
	int	i = -1;

	do
	{
		i++;
		s[i] = getche();
	} while (s[i] != 13);

	s[i] = 0;
}

// copy a string to other string
void	strcpy(char d[], char s[])
{
	int	i = 0;

	for (; s[i];i++)
		d[i] = s[i];
	d[i] = 0;
}

void	strcat(char d[], char s[])
{
	int	i = 0, j = 0;

	while (d[i])
		i++;

	for (; s[j];i++, j++)
		d[i] = s[j];
	d[i] = 0;
}

int		strchr(char s[], char ch)
{
	int	i = 0;

	while ( s[i] )
	{
		if ( s[i] == ch )
			return	i;
		i++;
	}

	return	-1;
}