C++：使用string類 

輸入使用：

#include <iostream>
#include <string>
using namespace std;

string s;

getline(cin, s);

#include <string>
#include <iostream>
using namespace std;

int lastWordLength(string s)
{
	int len = 0;
	while (s[len] != '\0')
	{
		len++;
	}
	int i = len - 1;
	int res = 0;
    for (int i=len-1; i>=0; i--)
    {
        if(s[i] == ' ')
            break;
        else
            res++;
    }
	return res;
}
int main()
{
	string s;
	getline(cin, s);
	int len = 0;
	len = lastWordLength(s);
	cout << len;
	return 0;
}
 

#include <iostream>
using namespace std;

int lastWordLength(char *s, int len)
{
	int i = len - 1;
	int res = 0;
	for (i; i >= 0; i--)
	{
		if (s[i] == ' ')
			break;
		else
			res++;
	}
	return res;
}
int main()
{
	char str[10000];
	cin.getline(str, 10000);
	int slen = strlen(str);
	int len = lastWordLength(str, slen);
	cout << len;
	return 0;
}