C++ 输入有空格一行的接收

#include<iostream>
#include<string>
using namespace std;
int main()
{
	char input_str[100];  //输入有空格的一行。cin默认以空格结束
	cin.getline(input_str, 100);
	int num_num = 0;
	int num_letter = 0;
	int num_space = 0;
	int num_other = 0;
	int len = strlen(input_str);
	cout << "len:" << len<<endl;
	for (int i = 0; i<len; i++) {
		if (input_str[i] >= '0' && input_str[i] <= '9')
			num_num++;
		else if ((input_str[i] >= 'A' && input_str[i] <= 'Z') || input_str[i] >= 'a' && input_str[i] <= 'z')
			num_letter++;
		else if (input_str[i] == ' ')
			num_space++;
		else
			num_other++;
	}

	cout << "letter:" << num_letter << endl;
	cout << "number:" << num_num << endl;
	cout << "space:" << num_space << endl;
	cout << "other character:" << num_other << endl;
	return 0;
}