Qt 科学计算器 使用后缀表达式解析

#include "computationalexpressions.h" #include <QDebug> ComputationalExpressions::ComputationalExpressions(QObject *parent) : QObject(parent) { init(); } void ComputationalExpressions::init() { if(!m_expStack.isEmpty()) m_expStack.clear(); if(!m_opStack.isEmpty()) m_opStack.clear(); if(!m_postfix.isEmpty()) m_postfix.clear(); m_opStack.push("#"); m_lefts = 0; } int ComputationalExpressions::getLevel(const QString &oper) { //运算符由低到高： if (oper == "#" || oper == "(") return 0; if (oper == "|" || oper == "&") return 1; if (oper == "=" || oper == "≠") return 2; if (oper == ">" || oper == "≥" || oper == "<" || oper == "≤") return 3; if (oper == "+" || oper == "-") return 4; if (oper == "*" || oper == "/" || oper == "%") return 5; if (oper == "!") return 6; return 0; } int ComputationalExpressions::toPostfix() { //对中缀表达式处理 for (int i = 0; i < m_exp.size(); ++i) { if (m_exp[i] == '(') m_lefts++; if (m_exp[i] == ')') m_lefts--; if ( (m_exp[i] == '-') && (m_exp[i + 1] == '(') && ( (i == 0) || ((i > 0) && !m_exp[i - 1].isDigit() && (m_exp[i - 1] != ')')) ) ) { m_exp.replace(i, 1, "-1*"); } else if (isOperator(m_exp[i]) && isOperator(m_exp[i + 1])) { if (m_exp.mid(i, 2) == "--") { if (i == 0) m_exp.remove(0, 2); else m_exp.replace(i, 2, "+"); } else if (m_exp.mid(i, 2) == "!!") { m_exp.remove(i, 2); continue; } //运算符错误，有2个连续的错误运算符 else if (!m_exp.mid(i, 2).contains("!") ) { return OPERATORERROR; } //三个连续的运算符肯定错误 else if (isOperator(m_exp[i + 2])) return OPERATORERROR; } else if (i > 0 && m_exp[i] == '(' && m_exp[i - 1].isDigit()) { m_exp.replace(i, 1, "*("); continue; } else if (i > 0 && m_exp[i] == ')' && m_exp[i + 1].isDigit()) { m_exp.replace(i, 1, ")*"); continue; } } //括号不匹配 if (m_lefts != 0) { return DOESNOTMATCHTHEPARENTHESES; } qDebug() << "中缀表达式为：" << m_exp; bool isNegative = false; for(int i = 0; i < m_exp.length(); i++) { if (isNegative && isOperator(m_exp[i])) { isNegative = false; } //是数字 if(m_exp[i].isDigit() || m_exp[i] == '.') { if ((m_postfix.right(1) != " ") && (!m_postfix.right(1)[0].isDigit()) && (!isNegative) && (m_postfix.right(1) != ".")) { if (i > 0) { qDebug() << "数字前加空格"; m_postfix.push_back(' '); } } m_postfix.push_back(m_exp[i]); qDebug() << m_postfix; } else if(m_exp[i] == '(') { m_opStack.push(m_exp.mid(i, 1)); } else if(m_exp[i] == ')') { while(m_opStack.top() != "(") { m_postfix.push_back(' '); m_postfix.push_back(m_opStack.pop()); } m_opStack.pop(); } else if ( (m_exp[i] == '-') && ( ((i > 0) && !m_exp[i - 1].isDigit() && (m_exp[i - 1] != ')')) || (i == 0) ) && (m_exp[i + 1].isDigit()) ) //是负号 { qDebug() << "是负号"; isNegative = true; if (i != 0) m_postfix.push_back(' '); m_postfix.push_back(m_exp[i]); qDebug() << m_postfix; continue; } else if(getLevel(m_exp.mid(i, 1)) > getLevel(m_opStack.top())) { if (i != 0) m_postfix.push_back(' '); m_opStack.push(m_exp.mid(i, 1)); qDebug() << m_postfix; } else { while(getLevel(m_exp.mid(i, 1)) <= getLevel(m_opStack.top())) { if (i != 0) m_postfix.push_back(' '); m_postfix.push_back(m_opStack.pop()); } m_opStack.push(m_exp.mid(i, 1)); qDebug() << m_postfix; } } while(m_opStack.top() != "#") { m_postfix.push_back(' '); m_postfix.push_back(m_opStack.pop()); } //去除前后的所有空格，将中间的多余空格全部转换为一个空格 m_postfix = m_postfix.simplified(); qDebug() << "后缀表达式为：" << m_postfix; return NOERROR; } int ComputationalExpressions::evaluation(double &results) { QString tem; QStack<double> ans; for(int i = 0; i < m_postfix.size(); i++) { qDebug() << m_postfix[i] << i; if((m_postfix[i] <= '9' && m_postfix[i] >= '0') || m_postfix[i] == '.') tem.push_back(m_postfix[i]); else if ( (m_postfix[i] == '-') && ( ((i > 0) && (m_postfix[i - 1] == ' ') && (m_postfix[i + 1].isDigit())) || (m_postfix[i + 1].isDigit() && (i == 0)) ) ) { //是负号 tem.push_back(m_postfix[i]); continue; } else if(m_postfix[i] == ' ') { if(!tem.isEmpty()) { ans.push(tem.toDouble()); tem.clear(); } qDebug() << ans.top() << tem.isEmpty(); } else { double a, b; a = ans.pop(); qDebug() << "a:" << a ; if (m_postfix[i] != '!') { b = ans.pop(); qDebug() << "b:" << b ; } if (m_postfix.mid(i, 1) == "+") ans.push(b + a); if (m_postfix.mid(i, 1) == "-") ans.push(b - a); if (m_postfix.mid(i, 1) == "*") ans.push(b * a); if (m_postfix.mid(i, 1) == "/") { if (a == 0) return DIVIDENDISZERO; else ans.push(b / a); } if (m_postfix.mid(i, 1) == "%") ans.push((int)b % (int)a); if (m_postfix.mid(i, 1) == "!") ans.push(!a); if (m_postfix.mid(i, 1) == "|") ans.push(a || b); if (m_postfix.mid(i, 1) == "&") ans.push(a && b); if (m_postfix.mid(i, 1) == "=") ans.push(a == b); if (m_postfix.mid(i, 1) == "≠") ans.push(a != b); if (m_postfix.mid(i, 1) == ">") ans.push(b > a); if (m_postfix.mid(i, 1) == "≥") ans.push(b >= a); if (m_postfix.mid(i, 1) == "<") ans.push(b < a); if (m_postfix.mid(i, 1) == "≤") ans.push(b <= a); qDebug() << "result:" << ans.top(); results = ans.top(); } } return NOERROR; } //返回值为错误提示(枚举中)，参数results保存计算的最终结果 int ComputationalExpressions::getResults(const QString &exp, double &results) { init(); m_exp = exp; switch (toPos