我想使用正则表达式为二次方程实现解析器。我想将其保留为控制台应用程序。我完成了正则表达式并在Debuggex中对其进行了测试。目前我有 2 个问题 - 我无法从 (ax^2+bx+c) 获取 a、b、c,并且我想使用向上和向下箭头添加类似 bash 的历史记录。提前致谢。我的代码:
#include <QCoreApplication>
#include <QRegExp>
#include <QString>
#include <QTextStream>
#include <QStringList>
#include <QDebug>
#include <cstdio>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
Q_UNUSED(a);
QTextStream cin(stdin, QIODevice::ReadOnly | QIODevice::Text);
QTextStream cout(stdout, QIODevice::WriteOnly | QIODevice::Text);
const QString regexText = R"(^[-]?\d*x\^2\s*[+,-]\s*\d*x\s*[+,-]\s*\d*$)";
while(true)
{
QRegExp regex(regexText);
cout << "Enter an equation to solve or press EOF(Ctrl+D/Z) to exit." << endl;
cout << "--> " << flush;
QString equation;
equation = cin.readLine();
if( equation.isNull() )
{
cout << endl;
cout << "Thanks for using quadric equation solver! Exitting..." << endl;
return 0;
}
int pos = regex.indexIn(equation);
QStringList captures = regex.capturedTexts();
qDebug() << captures;
}
}