统计英文句子中的字符个数

#include<iostream>
#include <string>
using namespace std ;
int count(string Str)  //统计字符串个数的函数
{
	int i = 0, cnt = 0;
	for (i=0; i<Str.length(); i++)
	{
		if (Str[i]>='a' && Str[i]<='z' || Str[i] >='A' && Str[i]<='Z' )
		cnt++;
	}
	cout<<"your str:"<<endl;  //展示输入内容
	cout << "str="<<Str<<endl ;
	return cnt;
}
void main()
{
	string Str;
	char ch;
	cout<<"input str:"<<endl;  //输入
	getline(cin , Str );
	int a = count(Str);
	cout << "字母个数：" <<a<<endl;
}