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。
