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C++文件读写代码分享

2020-01-26 15:03:12
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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.outWriting to the fileEnter your name: ZaraEnter your age: 9Reading from the fileZara9

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