C ++的流不写输出文件？ [英] C++ ofstream not writing to output file?

问题描述

代码应计算输入文本文件中a，b，c，d，e和f字符的数量，并将输出打印到第二个文本文件中。当我运行代码，它创建输出文件，但不写入任何东西。

 ＃include< iostream> 
＃include< fstream> 
＃include< cmath> 
 using namespace std; 
 
 
 int main（）{
 
 //为每个字符的数字建立计数器
 char x; 
 int acount = 0; 
 int bcount = 0; 
 int ccount = 0; 
 int dcount = 0; 
 int ecount = 0; 
 int fcount = 0; 
 
 ifstream iFile（plato.txt）; // define&打开文件
 ofstream oFile（statistics.txt）; 
 
 if（！iFile）{
 cout<<无法打开文件。 
 exit（1）; 
} 
 
 if（！oFile）{
 cout<<无法打开文件。 
 exit（1）; 
} 
 
 iFile>> x; 
 
 while（！iFile.eof（））{
 if（x =='a'|| x =='A'）{
 acount ++; 
} 
 else if（x =='b'|| x =='B'）{
 bcount ++; 
} 
 else if（x =='c'|| x =='C'）{
 ccount ++; 
} 
 else if（x =='d'|| x =='D'）{
 dcount ++; 
} 
 else if（x =='d'|| x =='D'）{
 dcount ++; 
} 
 else if（x =='f'|| x =='F'）{
 fcount ++; 
} 
} 
 
 
 
 oFile<<Number of a / A characters：<< acount; //将数字写入统计文件
 oFile<<\\\
数字b / B字符：<< bcount; 
 oFile<<\\\
个c / C字符数：<< ccount; 
 oFile<<\\\
数字d / D字符：<< dcount; 
 oFile<<\\\
 e / E字符数：<< ecount; 
 oFile<<\\\
F / F字符数：<< fcount; 
 
 
 //关闭文件
 iFile.close（）; 
 oFile.close（）; 
} 
  

解决方案

循环;你在循环中什么也不做，这会改变 ifile.eof（）的状态。当然，条件是错误的开始—你永远不想使用 ios_base :: eof（）作为循环中的条件。您的循环应该是：

  while（iFile>> x）{
  

，但是对于读取单个字符，使用 get 可能更简单。 >

The code is supposed to count the number of a, b, c, d, e, and f characters in the input text file and print the output into a second text file. When I run the code, it creates the output file but doesn't write anything into it.

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


int main(){

// establish counters for the number of each character
char x;
int acount=0;
int bcount=0;
int ccount=0;
int dcount=0;
int ecount=0;
int fcount=0;

 ifstream iFile("plato.txt"); //define & open files
 ofstream oFile("statistics.txt");

 if(!iFile){
  cout<<"The file could not be opened.";
  exit(1);
 }

 if(!oFile){
  cout<<"The file could not be opened.";
  exit(1);
 }

 iFile>>x;

 while(!iFile.eof()){
  if(x=='a'||x=='A'){
   acount++;
  }
  else if(x=='b'||x=='B'){
   bcount++;
  }
  else if(x=='c'||x=='C'){
   ccount++;
  }
  else if(x=='d'||x=='D'){
   dcount++;
  }
  else if(x=='d'||x=='D'){
   dcount++;
  }
  else if(x=='f'||x=='F'){
   fcount++;
  }
}



    oFile<<"Number of a/A characters: "<<acount; //write number of characters into statistics file
    oFile<<"\nNumber of b/B characters: "<<bcount;
    oFile<<"\nNumber of c/C characters: "<<ccount;
    oFile<<"\nNumber of d/D characters: "<<dcount;
    oFile<<"\nNumber of e/E characters: "<<ecount;
    oFile<<"\nNumber of f/F characters: "<<fcount;


//close files
 iFile.close();
 oFile.close();
}

解决方案

You've got an endless loop; you do nothing in the loop which would change the state of ifile.eof(). And of course, the condition is wrong to begin with—you never want to use ios_base::eof() as the condition in a loop. Your loop should probably be:

while ( iFile >> x ) {

, although for reading single characters, it might be simpler to use get.

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