模拟词法分析的过程，编写一个程序，用于统计文件中单词的总数

上机题：

模拟词法分析的过程，编写一个程序，用于统计文件中单词的总数，不同单词的数目。（假设输入文件中只包含字母和空格）

eg: I love Dalian and I love DLUT

单词总数：7

不同单词数目：5

#include <stdio.h>
#include <iostream>
#include <string.h>

int main()
{
	using namespace std;
	string sentence;//输入的字符串
	cout << "Please input the sentence:";
	getline(cin,sentence);
	int countlen = sentence.length();//字符串的长度
	int countchar = 1;//统计有多少个空格，+1即单词数量
	for (int i = 1; i <= countlen; i++) {
		if (sentence[i] == ' ' && sentence[i - 1] != ' ') {
			countchar++;
		}
	}
	cout << "单词总数：" << countchar<<endl;
	char sentencechar[20][20];//句子拆成单词
	int i = 0;//句子长度下标
	int j = 0;//单词下标
	int k = 0;//单词中字母下标
	while ( i <= countlen-1) {
		if (sentence[i] != ' ') {
			sentencechar[j][k] = sentence[i];
			k++;
			i++;
		}
		else if(sentence[i] == ' ') {
			sentencechar[j][k] = '\0';
			k = 0;
			j++;
			i++;
		}
	}
	int countcom[20] = {0};//统计相同单词数量
	int com = 0;
	//检查相同单词
	for (int m = 0; m <= j-1; m++) {
		for (int n = m + 1; n <= j; n++) {
			if (strcmp(sentencechar[m], sentencechar[n]) == 0) {
				countcom[com]++;
				com++;
			}
		}
	}
	int countdiffer = countchar;//不同单词=总词数-相同单词出现次数+1
	for (int m = 0; m < com; m++) {
		countdiffer = countdiffer - countcom[m];
	}
	cout << "不同单词数目：" << countdiffer;
	return 0;
}