#include
#include
#include
#include
using namespace std;
//从文件中读取每一行，然后消除前后空格，使其连成一个新的字符串。
int main()
{
    string newstring = "";
    vector str;
    ifstream fin("a.txt");
    string line;
    while (getline(fin, line))
        str.push_back(line);
    for (unsigned i = 0; i < str.size(); i++)
    {
        newstring += str[i].substr(str[i].find_first_not_of(" "),str[i].find_last_not_of(" ")-str[i].find_first_not_of(" ")+1);
    }
    cout