初步体验Qt Creator

用途：练习20以内2位数乘法速算的程序

功能1：支持用户设定题目数量

    std::cout << "请输入本次练习题目数量：";int numProblems = 0;std::string num;std::cin >> num;try {numProblems = std::stoi(num);MathQuiz quiz(numProblems);quiz.runQuiz();} catch (const std::invalid_argument& e) {std::cerr << "请输入合法的整数结果！\n";continue;}

功能2：支持随机生成期望数量的题目

void MathQuiz::generateProblems() {for (int i = 0; i < numProblems; i++) {int randomValue1 = generateRandomValue();int randomValue2 = generateRandomValue();problems.emplace_back(randomValue1, randomValue2);}
}int MathQuiz::generateRandomValue() { return randomGenerator.bounded(10, 21); }

功能3：支持判断用户输入结果的准确性

bool MathQuiz::promptAndCheckAnswer(int value1, int value2, int index) {std::cout << std::format("{}-{} 请计算：{}×{}=", index, numProblems, value2,value1);std::string str;int result = 0;std::cin >> str;try {result = std::stoi(str);} catch (const std::invalid_argument& e) {std::cerr << "请输入合法的整数结果！\n";}return result == value2 * value1;
}

功能4：循环出题，并支持记录计算错误的题目

  std::map<int, std::string> incorrectProblems;for (int i = 0; i < numProblems; i++) {const auto& problem = problems[i];bool correct = false;while (!correct) {correct = promptAndCheckAnswer(problem.first, problem.second, i + 1);if (!correct) {std::cout << "回答错误，请再试一次。\n";incorrectProblems.insert(std::pair<int, std::string>(i + 1, std::format("{}×{}", problem.first, problem.second)));} else {if (incorrectProblems.find(i + 1) == incorrectProblems.end()) {numCorrect++;}break;}}}

功能5：支持统计正确题目数、平均计算耗时和总计耗时

void MathQuiz::printResults(double elapsedTime) {double correctPercent = numCorrect * 100 / numProblems;QTextStream out(stdout);QString outstr =QString("共%2题，答对%1题，正确率：%3%，平均用时：%4秒，累计用时：%5秒。\n").arg(numCorrect).arg(numProblems).arg(correctPercent).arg(elapsedTime / numProblems).arg(elapsedTime);out << outstr;
}

程序结构：

main.cpp主程序

#include <windows.h>#include <QCoreApplication>
#include <iostream>#include "mathquiz.h"int main() {SetConsoleOutputCP(CP_UTF8);while (true) {std::cout << "请输入本次练习题目数量：";int numProblems = 0;std::string num;std::cin >> num;try {numProblems = std::stoi(num);MathQuiz quiz(numProblems);quiz.runQuiz();} catch (const std::invalid_argument& e) {std::cerr << "请输入合法的整数结果！\n";continue;}std::cout << "是否继续练习？ （y/n）：";std::string yn;std::cin >> yn;if (yn != "y" && yn != "Y") break;}return 0;
}

mathquiz.cpp，一个计算功能类

#include "mathquiz.h"#include <iostream>MathQuiz::MathQuiz(int numProblems) : numCorrect(0), numProblems(numProblems) {randomGenerator.seed(QTime::currentTime().msec());generateProblems();
}void MathQuiz::runQuiz() {QTime startTime = QTime::currentTime();std::map<int, std::string> incorrectProblems;for (int i = 0; i < numProblems; i++) {const auto& problem = problems[i];bool correct = false;while (!correct) {correct = promptAndCheckAnswer(problem.first, problem.second, i + 1);if (!correct) {std::cout << "回答错误，请再试一次。\n";incorrectProblems.insert(std::pair<int, std::string>(i + 1, std::format("{}×{}", problem.first, problem.second)));} else {if (incorrectProblems.find(i + 1) == incorrectProblems.end()) {numCorrect++;}break;}}}QTime endTime = QTime::currentTime();double elapsedTime = startTime.msecsTo(endTime) / 1000.0;printResults(elapsedTime);printIncorrectProblems(incorrectProblems);
}void MathQuiz::generateProblems() {for (int i = 0; i < numProblems; i++) {int randomValue1 = generateRandomValue();int randomValue2 = generateRandomValue();problems.emplace_back(randomValue1, randomValue2);}
}int MathQuiz::generateRandomValue() { return randomGenerator.bounded(10, 21); }bool MathQuiz::promptAndCheckAnswer(int value1, int value2, int index) {std::cout << std::format("{}-{} 请计算：{}×{}=", index, numProblems, value2,value1);std::string str;int result = 0;std::cin >> str;try {result = std::stoi(str);} catch (const std::invalid_argument& e) {std::cerr << "请输入合法的整数结果！\n";}return result == value2 * value1;
}void MathQuiz::printResults(double elapsedTime) {double correctPercent = numCorrect * 100 / numProblems;QTextStream out(stdout);QString outstr =QString("共%2题，答对%1题，正确率：%3%，平均用时：%4秒，累计用时：%5秒。\n").arg(numCorrect).arg(numProblems).arg(correctPercent).arg(elapsedTime / numProblems).arg(elapsedTime);out << outstr;
}void MathQuiz::printIncorrectProblems(const std::map<int, std::string>& incorrectProblems) {if (incorrectProblems.empty()) {return;}std::cout << "回答错误的题目：\n";int i = 1;for (const auto& it : incorrectProblems) {const auto& problem = problems[it.first - 1];std::cout << "题目 " << i << ": " << it.second << "="<< (problem.first * problem.second) << "\n";i++;}
}

mathquiz.h头文件

#ifndef MATHQUIZ_H
#define MATHQUIZ_H#include <QRandomGenerator>
#include <QTime>
#include <vector>class MathQuiz {public:MathQuiz(int numProblems);void runQuiz();private:void generateProblems();int generateRandomValue();bool promptAndCheckAnswer(int value1, int value2, int index);void printResults(double elapsedTime);void printIncorrectProblems(const std::map<int, std::string>& incorrectProblems);QRandomGenerator randomGenerator;int numCorrect;int numProblems;std::vector<std::pair<int, int>> problems;
};#endif  // MATHQUIZ_H

运行效果

遇到问题总结：

Qt Creator编写Console程序，运行时没反应，应勾选下面选项

Qt Creator编写Console程序，汉字输出乱码

原因1：默认字符输出位置设置的值与Windows控制台默认字符集（GBK）不符

默认字符输出查看与修改

确定控制台窗口使用的编码格式：

原因2：文件编码格式与系统不兼容

原因3：部分库默认使用UTF-8，输出应转码，比如QTextStream

QTextStream out(stdout);
out.setEncoding (QStringConverter::System); 

还有个方法，添加windows.h的引用，并在main开始时，添加：

SetConsoleOutputCP(CP_UTF8);

注意：将所有源代码以及系统文件编辑器默认编码均修改为UTF-8即可