C语言统计字符串中单词的个数

 【说明】you're，I'm ，类似这种的单词是一个单词。

主要思路就是，从头到尾遍历字符串，不同的状态直接的切换可以确定是否为单词的个数加1.

当状态从在单词里转换为不在单词里时，单词的个数加1.

#define BEGIN	0
#define INWORD	1
#define OUTWORD	2
#define END		3
int GetWordNums(const char *str)
{
	int Number = 0;
	if (NULL == str)return Number;

	int tag = BEGIN;
	for (int i = 0; tag != END; i++)
	{
		switch (tag)
		{
		case BEGIN:
			if (isalpha(str[i]))
				tag = INWORD;
			else
				tag = OUTWORD;
			break;
		case OUTWORD:
			if (isalpha(str[i]))
				tag = INWORD;
			break;
		case INWORD:
			if (!isalpha(str[i]) && str[i] != '\'' && str[i] != '-')
			{
				Number++;
				tag = OUTWORD;
			}
			break;
		}
		if (str[i] == '\0')
		{
			tag = END;
		}
	}
	return Number;
}