#include <iostream>
#include "string"
#include "cmath"
#include "iomanip"
using namespace std;int main()
{   //默认情况下，输入操作符忽略空白while(cin >> ch)cout << ch;//可以通过操纵符来强制不忽略空白cin >> noskipws;while(cin >> ch)cout << ch;cin >> skipws; //reset cin to default state so that it discards whitespace//通过未格式化的IO操作，我们一次一个字节处理流，不忽略空白while(cin.get(ch))cout.put(ch);return 1;
}

#include <iostream>
#include "string"
#include "cmath"
#include "iomanip"
using namespace std;int main()
{   int ch;while((ch = cin.get()) != EOF)cout.put(ch);return 1;
}

// set the indicated marker a fixed position within a file or string
seekg(new_position); // set read marker
seekp(new_position); // set write marker
// offset some distance from the indicated position
seekg(offset, dir); // set read marker
seekp(offset, dir); // set write marker

#include <iostream>
#include "string"
#include "cmath"
#include "iomanip"
using namespace std;int main()
{   ostringstream writerStr;ostringstream::pos_type mark = writerStr.tellp();//...if (cancelEntry)//return to marked positionwriterStr.seekp(mark);return 1;
}

#include <iostream>
#include "string"
#include "cmath"
#include "iomanip"
#include "fstream"
using namespace std;int main()
{   //open for input and output and pre-position file pointers to end of filefstream inOut("C:\\httpdownload.txt", fstream::ate | fstream::in | fstream::out);if (!inOut){cerr << "Open file error" << endl;return EXIT_FAILURE;}//inOut is opened in ate mode, so it starts out positioned at the end,//which we must remember as it is the original end-of-file positionifstream::pos_type ptEndMark = inOut.tellg();inOut.seekg(0, fstream::beg);int cnt = 0;string line;// while we haven't hit an error and are still reading the original data// and successfully read another line from the filewhile(inOut && inOut.tellg() != ptEndMark && getline(inOut, line)){cnt += line.size() + 1;ifstream::pos_type ptCurrMark = inOut.tellg();inOut.seekp(0, fstream::end);inOut << cnt;if (ptCurrMark != ptEndMark)inOut << " ";inOut.seekg(ptCurrMark);}inOut.clear(); //clear flags in case we hit an errorinOut.seekp(0, fstream::end); // seek to endinOut << "\n"; //write a newline at end of filereturn 0;return 1;
}