基于C++实现的四则运算计算器源代码+课程设计报告

/** * Copyright (c) 2024, Harry Huang * @ MIT License */ #include <iostream> #include <iomanip> #include <cmath> #include <string> #include <sstream> using namespace std; namespace Calculator { const long double MAX_NUM = LLONG_MAX; const int MAX_DIGITS = (int)floor(log10(MAX_NUM)) - 2; const int MAX_PRECISION = numeric_limits<long double>::digits10; /** * @brief Number status. */ enum NumberStatus { ZERO_DIVISION = -2, OVERFLOWED = -1, NONE = 0, OKAY = 1 }; /** * @brief Wrapped long double number. */ struct Number { public: NumberStatus status; long double value; Number(NumberStatus status, long double value) { this->status = status; this->value = value; } Number(long double value) { this->status = NumberStatus::OKAY; this->value = value; } inline Number add(Number other) { if (status != NumberStatus::OKAY || other.status != NumberStatus::OKAY) { return Number(NumberStatus::NONE, 0); } long double a = value; long double b = other.value; bool of = (a > 0 && b > 0 && a > MAX_NUM - b) || (a < 0 && b < 0 && a < b - MAX_NUM); return Number(of ? NumberStatus::OVERFLOWED : NumberStatus::OKAY, a + b); } inline Number minus(Number other) { if (status != NumberStatus::OKAY || other.status != NumberStatus::OKAY) { return Number(NumberStatus::NONE, 0); } long double a = value; long double b = other.value; bool of = (a > 0 && -b > 0 && a > MAX_NUM - -b) || (a < 0 && -b < 0 && a < MAX_NUM - -b); return Number(of ? NumberStatus::OVERFLOWED : NumberStatus::OKAY, a - b); } inline Number multiply(Number other) { if (status != NumberStatus::OKAY || other.status != NumberStatus::OKAY) { return Number(NumberStatus::NONE, 0); } long double a = value; long double b = other.value; bool of = fabs(b) > fabs(MAX_NUM / a); return Number(of ? NumberStatus::OVERFLOWED : NumberStatus::OKAY, a * b); } inline Number divide(Number other) { if (status != NumberStatus::OKAY || other.status != NumberStatus::OKAY) { return Number(NumberStatus::NONE, 0); } long double a = value; long double b = other.value; if (b == 0) { return Number(NumberStatus::ZERO_DIVISION, 0); } bool of = fabs(b) < fabs(a / MAX_NUM); return Number(of ? NumberStatus::OVERFLOWED : NumberStatus::OKAY, a / b); } inline string toString() { if (value == 0) { return "0"; } int intDigits = max(0, (int)floor(log10(fabs(value)))) + 1; int precision = max(0, MAX_PRECISION - intDigits); ostringstream oss; oss << fixed << setprecision(precision) << value; string formatted = oss.str(); int dotIdx = formatted.find('.'); if (dotIdx != std::string::npos) { int lastNonZero = formatted.find_last_not_of('0'); if (lastNonZero == dotIdx) { formatted.erase(dotIdx); } else { formatted.erase(lastNonZero + 1); } } return formatted; } }; /** * @brief Char-by-char number parser. */ struct NumberReader { private: long long value; int digitLeft; int digitRight; bool isStarted; bool isEnded; bool isNegative; bool isDecimal; public: NumberReader() { value = 0; digitLeft = 0; digitRight = 0; isStarted = false; isEnded = false; isNegative = false; isDecimal = false; } inline bool read(char c) { if (c == ' ') { flush(); return true; } if (!isEnded) { if ('0' <= c && c <= '9') { value = value * 10 + (c - '0'); digitLeft += !isDecimal; digitRight += isDecimal; isStarted = true; return true; } if (c == '.' && !isDecimal) { isDecimal = true; isStarted = true; return true; } if (c == '-' && !isStarted) { isNegative = !isNegative; return true; } } return false; } inline bool flush() { if (isStarted) { isEnded = true; } return isEnded; } inline bool isFlushed() { return isStarted && isEnded; } inline bool isOverflowed() { return digitLeft + digitRight > MAX_DIGITS; } inline Number get() { long double rst = value; for (int i = 0; i < digitRight; i++) { rst /= 10.0; } if (isNegative) { rst = -rst; } return Number(isOverflowed() ? NumberStatus::OVERFLOWED : NumberStatus::OKAY, rst); } }; /** * @brief The type indicator for Expression. */ enum ExpressionType { ERR_OVERFLOW = -3, ERR_SYNTAX = -2, EXIT = -1, UNSET = 0, OP_ADD = 1, OP_MINUS = 2, OP_MULTIPLY = 3, OP_DIVIDE = 4, MEM_ADD = 5, MEM_MINUS = 6, MEM_CLEAR = 7, MEM_RECALL = 8 }; /** * @brief The expression parser for input streams. */ struct Expression { public: ExpressionType type; NumberReader num1; NumberReader num2; Expression(istream& is) { type = ExpressionType::UNSET; num1 = NumberReader(); num2 = NumberReader(); char input[1024]; is.getline(input, 1024); int inputLen = strlen(input); for (int i = 0; i < inputLen; i++) { char c = input[i]; char nextC = i + 1 < inputLen ? input[i + 1] : '\0'; if (!num1.read(c) && !(num1.flush() && num2.read(c))) { switch (c) { case '+': case '-': case '*': case '/': if (type || !num1.flush()) { type = ExpressionType::ERR_SYNTAX; return; } switch (c) { case '+': type = ExpressionType::OP_ADD; break; case '-': type = ExpressionType::OP_MINUS; break; case '*': type = ExpressionType::OP_MULTIPLY; break; case '/': type = ExpressionType::OP_DIVIDE; break; } break; case ' ': case '\t': break; case '#': if (type) { type = ExpressionType::ERR_SYNTAX; return; } type = ExpressionType::EXIT;