C++期末考试，请帮忙啊！

[qingzhai]

write a program to copy one text file into another text file into another text file in which the lines are numbered 1,2,3...with a number at the left of each line.
写一个程序将一个文件的内容复制到另一个文件上，并在内容前面的每一行标记上１，２，３．．．

[waizqfor]

[Quote=引用 8 楼 xiaoyisnail 的回复:]
C/C++ code
#include <fstream>
#include <iostream>
#include <string>
using namespace std;

int main()
{
ifstream in("in.txt",fstream::in);
if(!in)
{
cerr<<"error"<<endl;
exit(1);
}

ofstream out("out.txt",fstream::out);
if(!out)
{
cerr<<"error"<<endl;
exit(1);
}

string line;
int line_no = 1;
while…
[/Quote]
文件按行读写 换行在前面加一个标记（1 2 3） 基本文件操作

[frcsun]

今晚我们也考试，先看下，晚上考完了在解决~~~

[qingzhai]

好

[OenAuth.Net]

百度一下，文件按行读写

[无话可言]

ifstream infile("1.txt");
if(!infile){
cout<<"Can't open 1.txt"<<endl;
return 1;
}
ofstream outfile("2.txt", ios::app);
if(!outfile){
cout<<"Can't open 2.txt"<<endl;
return 1;
}
int lineNo = 1;
string lineString;
outfile <<endl; //And a new line.
//Read One line and put in line, write the formate to outfile
while(infile >> lineString){
outfile << lineNo << " " << lineString <<endl;
lineNo++;
}

infile.close();
outfile.close();

[Jinhao]

#include <iostream>
#include <sstream>

int main( int argc, char* argv )
{
    std::string str = "646f20697420796f757273656c66";
    char * dest = new char[str.size()];
    for(int i = 0; i < str.size() / 2; ++i)
    {
        std::stringstream ss;
        ss<<std::hex<<str.substr(i * 2, 2);
        int x;
        ss>>x;
        dest[i] = x;
    }
    dest[str.size()/2] = 0;
	std::cout<<dest<<std::endl;
    delete [] dest;
    std::system("pause");
}

[fo1_sky]

基本文件读写呀

[tangshuiling]

类似的代码可实现：

int i=1;
string str;
ifstream ifile("c:\\ifile.txt");  //没有必要的异常检测，楼主自己写吧
ofstream ofile("c:\\ofile.txt");
while(getline(ifile,str))
{
  ofile<<i++;
  str=':'+str;
  ofile<<str<<endl;
}

[xiaoyisnail]

#include <fstream>
#include <iostream>
#include <string>
using namespace std;

int main()
{
	ifstream in("in.txt",fstream::in);
	if(!in)
	{
		cerr<<"error"<<endl;
		exit(1);
	}

	ofstream out("out.txt",fstream::out);
	if(!out)
	{
		cerr<<"error"<<endl;
		exit(1);
	}

	string line;
	int line_no = 1;
	while(getline(in, line))
	{
		out<<line_no<<" "<<line<<endl;
		++line_no;
	}
	
	return 0;
}