C++文件读写代码分享

编写一个程序，统计data.txt文件的行数，并将所有行前加上行号后写到data1.txt文件中。

算法提示：

行与行之间以回车符分隔，而getline()函数以回车符作为终止符。因此，可以采用getline()函数读取每一行，再用一个变量i计算行数。

（1）实现源代码

#include <iostream>
#include <fstream>
#include <string>
#include <sstream>

using namespace std;

int coutFile(char * filename,char * outfilename)
{
  ifstream filein;
  filein.open(filename,ios_base::in);
  ofstream fileout;
  fileout.open(outfilename,ios_base::out);
  string strtemp;
  int count=0;
  while(getline(filein,strtemp))
  {
    count++;
    cout<<strtemp<<endl;
    fileout<<count<<" "<<strtemp<<endl;
  }
  filein.close();
  fileout.close();
  return count;
}


void main()
{
  cout<<coutFile("c:\\data.txt","c:\\data1.txt")<<endl;
}

再来一个示例：

下面的C++代码将用户输入的信息写入到afile.dat，然后再通过程序读取出来输出到屏幕

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

int main ()
{

  char data[100];

  // open a file in write mode.
  ofstream outfile;
  outfile.open("afile.dat");

  cout << "Writing to the file" << endl;
  cout << "Enter your name: ";
  cin.getline(data, 100);

  // write inputted data into the file.
  outfile << data << endl;

  cout << "Enter your age: ";
  cin >> data;
  cin.ignore();

  // again write inputted data into the file.
  outfile << data << endl;

  // close the opened file.
  outfile.close();

  // open a file in read mode.
  ifstream infile;
  infile.open("afile.dat");

  cout << "Reading from the file" << endl;
  infile >> data;

  // write the data at the screen.
  cout << data << endl;

  // again read the data from the file and display it.
  infile >> data;
  cout << data << endl;

  // close the opened file.
  infile.close();

  return 0;
}

程序编译执行后输出如下结果

$./a.out
Writing to the file
Enter your name: Zara
Enter your age: 9
Reading from the file
Zara
9

以上所述就是本文的全部内容了，希望大家能够喜欢。