linenum.cpp

ThinkingC++中文版

//: C11:Linenum.cpp
// From Thinking in C++, 2nd Edition
// Available at http://www.BruceEckel.com
// (c) Bruce Eckel 2000
// Copyright notice in Copyright.txt
//{T} Linenum.cpp
// Add line numbers
#include "../require.h"
#include <vector>
#include <string>
#include <fstream>
#include <iostream>
#include <cmath>
using namespace std;

int main(int argc, char* argv[]) 
{
  requireArgs(argc, 1, "Usage: linenum file\n"
    "Adds line numbers to file"); //提示该执行文件的用法,在dos界面下，在执行文件的目录下
  ifstream in(argv[1]);//打开文件
  assure(in, argv[1]);
  string line;
  vector<string> lines;
  while(getline(in, line)) // Read in entire file
    lines.push_back(line);
  if(lines.size() == 0) return 0;
  int num = 0;
  // Number of lines in file determines width:
  const int width = 
    int(log10((double)lines.size())) + 1;
  for(int i = 0; i < lines.size(); i++) {
    cout.setf(ios::right, ios::adjustfield);
    cout.width(width);
    cout << ++num << ") " << lines[i] << endl;
  }
} ///:~