我正在为我的C ++类开发一个最终项目。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的答案。此外，学生的姓名和分数需要在另一个文本文件中，以便学生查看它们以查看他们的分数。该程序answer.txt和scores.txt加上两个函数以及您可以使用的其他内容，您需要使用此类课程时间。
我无法从文件answer.txt中读取个别答案。我试图一次阅读一个答案，并将其与用户在名为check_answer的函数中输入的答案进行比较。我使用整数而不是字符来允许我轻松检查大写和小写（通过添加32）。该程序编译，但唯一的问题是，在我回答第一个问题后，所有其他问题弹出"You answered correctly!"并且程序已完成运行。
我正在使用DevC ++。下面是我的程序代码和txt文件answers.txt的内容。
#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 TRIVIA\n";
cout << "Enter the letter corresponding to the correct answer choice, then press enter.\n";
cout << "\nQuestion 1\n" << "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 2\n" << "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 3\n" << "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 4\n" << "What is the name of the organ on the Great White Shark that allows it to\nsense 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 5\n" << "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 6\n" << "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 7\n" << "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 8\n" << "What is the tactic used by Great Whites to attack prey on the surface\nof 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 9\n" << "After spotting surface prey from below, Great Whites swim upward and launch\nthemselves 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 10\n" << "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 11\n" << "Of the following, which is the best location to view Great White\nbreaching 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 12\n" << "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 13\n" << "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 14\n" << "After eating a marine mammal (such as a seal or sea lion), a Great White\nShark 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 15\n" << "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 16\n" << "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 17\n" << "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 18\n" << "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 19\n" << "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 20\n" << "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;
}
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非常感谢帮助。非常感谢您花时间看这个！
答案 0 :(得分：1)
我认为问题是你试图将一个字符读成一个整数：
int x, answer;
cin >> x;
基本上cin >> x说“从标准输入中读取整数到x”。问题是流中没有整数，只是一个字符。因此，读取操作无法和该字符留在流中。下次您尝试阅读答案时，您最终会一次又一次地阅读相同的字符。
首先，您应该重新考虑使用整数来选择答案。你真的需要一个整数来达到你想达到的目的吗？您也可以使用char算术运算......
一般建议：始终将数据与代码分开......在这种情况下，您应该将问题放在单独的文件中。这将使您的代码更易读，更易于管理。