#include
#include
#include
using namespace std;
int main()
{
string s;
cout<<"请输入一个英文句子:"<
while (cin>>s)
{
int len = s.length(), i = 0;
while (i != len)
{
islower(s[i]) ? s[i] = toupper(s[i]) :s[i] = tolower(s[i]);
++i;
}
cout<<"\n输出结果为:"<<s<<endl;
}
cout<<"句子的长度为:"<<s.size()<<endl;
return 0;
}