将文本文件abc.txt中的所有行加上行号后写到newabc.txt文件中
代码
#include <iostream>
#include <cstdlib>
#include <fstream>
using namespace std;
int main()
{
    fstream outfile,infile;
    infile.open("abc.txt",ios::in); // (1)
    if(!infile) {
        cout<<"Can’t open the file."<<endl;
        abort();
    }
    outfile.open("newabc.txt",ios::out);//(2)
    if(!outfile) {
        cout<<"Can’t open the file."<<endl;
        abort();
    }
    char buf[80];
    int i=1;
    while(!infile.eof()) // (3)
    {
        infile.getline(buf,80); // (4)
        outfile<<i++<<": "<<buf<<endl; //(5)
    }
    infile.close();
    outfile.close();
    return 0;
}
原文:http://blog.csdn.net/blue_skyrim/article/details/46402563