如何访问和读取 C++ 文件中的各个行

我正在为我的C++课做一个最终项目。 这是一个多项选择测验，其中需要通过将用户的答案与包含所有 20 个答案的answer.txt中的相应答案进行比较来检查正确答案。 此外，学生的姓名和分数需要位于另一个文本文件中，允许学生查看它以查看他们的分数。 该程序，answer.txt和scores.txt加上两个功能以及您从本课程期间学到的内容中可以使用的任何其他功能都需要使用。

我在阅读文件answer.txt中的单个答案时遇到问题。 我正在尝试一次阅读一个答案，并将其与用户在名为 check_answer 的函数中输入的所有答案进行比较。 我使用整数而不是字符来让我轻松检查大写和小写(通过添加 32(。 程序编译，但唯一的问题是，在我回答第一个问题后，所有其他问题都弹出"You answered correctly!"，程序完成运行。

我正在使用DevC ++。 下面是我的程序的代码和 txt 文件的内容 answers.txt .

#include<iostream.h>
#include<fstream.h>
#include<string.h>
int total_correct = 0;
ifstream infile;
void name_prompt();
void check_answer();
void scores();
int main()
{
      name_prompt();
      cout << "nGREAT WHITE SHARK TRIVIAn";
      cout << "Enter the letter corresponding to the correct answer choice, then press enter.n";
      cout << "nQuestion 1n" << "What is the Great White Shark's scientific name?n";
      cout << "A. Hemipristis elongatus" << endl;    // Snaggletooth shark
      cout << "B. Odontaspis ferox" << endl;         // Smalltooth sand tiger
      cout << "C. Carcharodon carcharias" << endl;   // Great White Shark
      cout << "D. Oxynotus caribbaeus" << endl;      // Caribbean roughshark
      check_answer();
      cout << "nQuestion 2n" << "Carcharodon is a mix of two Greek words that translate in English to:n";
      cout << "A. Ragged tooth" << endl;    
      cout << "B. Swift killer" << endl;        
      cout << "C. White fish" << endl; 
      cout << "D. Sea warrior" << endl;     
      check_answer();
      cout << "nQuestion 3n" << "How big do Great White Sharks grow?n";
      cout << "A. Approximately 10 feet long" << endl;    
      cout << "B. Approximately 17 feet long" << endl;        
      cout << "C. Approximately 21 feet long" << endl; 
      cout << "D. Approximately 30 feet long" << endl;  
      check_answer();
      cout << "nQuestion 4n" << "What is the name of the organ on the Great White Shark that allows it tonsense electromagnetic fields radiating from its prey?n";
      cout << "A. Duodenom antennae" << endl;    
      cout << "B. Ampullae of Lorenzini" << endl;        
      cout << "C. Spiracle gland" << endl; 
      cout << "D. Dermal denticles" << endl;     
      check_answer();
      cout << "nQuestion 5n" << "How long do Great White Shark mothers stay with their young?n";
      cout << "A. No time whatsoever" << endl;    
      cout << "B. 3 months" << endl;        
      cout << "C. 6 months" << endl; 
      cout << "D. 1 year" << endl;     
      check_answer();
      cout << "nQuestion 6n" << "How old are female Great Whites when they usually bear their first young?n";
      cout << "A. 2-4 years" << endl;    
      cout << "B. 6-8 years" << endl;        
      cout << "C. 8-10 years" << endl; 
      cout << "D. 12-14 years" << endl;     
      check_answer();
      cout << "nQuestion 7n" << "What is the favorite prey of an adult Great White Shark?n";
      cout << "A. Crustaceans" << endl;    
      cout << "B. Fish" << endl;        
      cout << "C. Plankton" << endl; 
      cout << "D. Sea mammals" << endl;     
      check_answer();
      cout << "nQuestion 8n" << "What is the tactic used by Great Whites to attack prey on the surfacenof the water?n";
      cout << "A. Attack from the side" << endl;    
      cout << "B. Attack from below" << endl;        
      cout << "C. Jump out of the water and land on the desired target" << endl; 
      cout << "D. Wait until the surface prey dives and then attack" << endl;     
      check_answer();
      cout << "nQuestion 9n" << "After spotting surface prey from below, Great Whites swim upward and launchnthemselves out of the water grabbing their prey. This is called: n";
      cout << "A. Skipping" << endl;    
      cout << "B. Jumping" << endl;        
      cout << "C. Breaching" << endl; 
      cout << "D. Charging" << endl;     
      check_answer();
      cout << "nQuestion 10n" << "How do Great White Sharks consume their food?n";
      cout << "A. Rip off chunks of meat and swallow them whole" << endl;    
      cout << "B. Chew thoroughly and swallow" << endl;        
      cout << "C. Hold in mouth, let saliva break it down, and then swallow" << endl; 
      cout << "D. Suck out bodily fluids and leave carcass" << endl;     
      check_answer();
      cout << "nQuestion 11n" << "Of the following, which is the best location to view Great Whitenbreaching behavior?n";
      cout << "A. Myrtle Beach, South Carolina" << endl;    
      cout << "B. Cape Cod, Massachusetts" << endl;        
      cout << "C. Oban, Scotland" << endl; 
      cout << "D. False Bay, South Africa" << endl;     
      check_answer();
      cout << "nQuestion 12n" << "On average, how many non-fatal Great White Shark attacks occur each year?n";
      cout << "A. 2-3" << endl;    
      cout << "B. 3-4" << endl;        
      cout << "C. 8-10" << endl; 
      cout << "D. 15-20" << endl;     
      check_answer();
      cout << "nQuestion 13n" << "What is one of the main predators juvenille Great Whites have to watch out for?n";
      cout << "A. Humboldt Squid" << endl;    
      cout << "B. Various Whale Species" << endl;        
      cout << "C. Lion's Mane Jellyfish" << endl; 
      cout << "D. Other Great White Sharks" << endl;     
      check_answer();
      cout << "nQuestion 14n" << "After eating a marine mammal (such as a seal or sea lion), a Great WhitenShark can go how long without another large meal?n";
      cout << "A. 3-4 days" << endl;    
      cout << "B. 1 week" << endl;        
      cout << "C. 2 weeks" << endl; 
      cout << "D. 1-2 months" << endl;     
      check_answer();
      cout << "nQuestion 15n" << "How fast can adult Great White Sharks swim?n";
      cout << "A. Up to 64 mph" << endl;    
      cout << "B. Up to 43 mph" << endl;        
      cout << "C. Up to 20 mph" << endl; 
      cout << "D. Up to 14 mph" << endl; 
      check_answer();
      cout << "nQuestion 16n" << "The teeth of a Great White Shark can measure up to?n";
      cout << "A. 0.5 in" << endl;    
      cout << "B. 1.0 in" << endl;        
      cout << "C. 2 in" << endl; 
      cout << "D. 2.5 in" << endl;         
      check_answer();
      cout << "nQuestion 17n" << "Great White Sharks have which of the following?n";
      cout << "A. Acute hearing" << endl;    
      cout << "B. Good eyesight" << endl;        
      cout << "C. Keen sense of smell" << endl; 
      cout << "D. All of the above" << endl;     
      check_answer();
      cout << "nQuestion 18n" << "In addition to its normal function, a Great White Shark's liver helps it to:n";
      cout << "A. Float" << endl;    
      cout << "B. Swim aerodynamically" << endl;        
      cout << "C. Sense prey" << endl; 
      cout << "D. All of the above" << endl;     
      check_answer();
      cout << "nQuestion 19n" << "Great White Sharks can detect tiny amounts of blood up to how far away?n";
      cout << "A. 500 feet" << endl;    
      cout << "B. 1 mile" << endl;        
      cout << "C. 3 miles" << endl; 
      cout << "D. 5 miles" << endl;     
      check_answer();
      cout << "nQuestion 20n" << "Great White Shark's mouths contain up to how many teeth?n";
      cout << "A. 50" << endl;    
      cout << "B. 100" << endl;        
      cout << "C. 200" << endl; 
      cout << "D. 300" << endl;     
      check_answer();
      scores();
      system("pause");
      return 0;
}
void name_prompt()
{
     char user_name[30];
     ofstream outfile;
     cout << "Please enter your name: ";
     cin.get(user_name, 30);
     outfile.open("SCORES.TXT", ios::out);
     if(!outfile)
      {
                 cout << "Error opening file.n";
      }
      outfile << user_name << endl;
      outfile.close();
}
**void check_answer()
{
      ifstream infile;
      infile.open("ANSWERS.TXT", ios::in);
      if(!infile)
      {
                 cout << "Error opening file.n";
      }
     int x, answer;
      cin >> x;
      infile >> answer;
      if(x == answer || x == (answer + 32))
      {
           cout << "You answered correctly!n" << endl;
           total_correct++;
      } 
      else
      {
          cout << "You answered incorrectly.n" << endl;
      }
      infile.close();
}**
void scores()
{
     ofstream outfile2;         
     int score;
     score = (total_correct * 5);
     outfile2.open("SCORES.TXT", ios::app);
     if(!outfile2)
      {
                 cout << "Error opening file.n";
      }
      outfile2 << "You answered " << total_correct << " out of 20 questions correctly." << endl;
      outfile2 << "You earned a score of " << score << "%.n";
      outfile2.close();
      cout << "Please see SCORES.TXT if you wish to view your results." << endl;
}

"答案.txt"的内容：

C
A
C
B
A
D
D
B
C
A
D
A
D
D
B
D
D
A
C
D

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