編譯類問題

Question

嘗試編譯c ++類程序時，不斷出現這些錯誤。

testStock.cpp：在函數'int main（）'中：testStock.cpp：8：錯誤：未在此范圍內聲明'Stock'testStock.cpp：8：錯誤：預期;' before 'first' testStock.cpp:9: error: 'first' was not declared in this scope testStock.cpp:12: error: expected ;' before 'first' testStock.cpp:9: error: 'first' was not declared in this scope testStock.cpp:12: error: expected ;' 在“第二” testStock.cpp：13之前：錯誤：未在此范圍中聲明“第二”

股票.h

#ifndef STOCK_H
#define STOCK_H
using namespace std;

class Stock
{
 private:
  string symbol;
  string name;
  double previousClosingPrice;
  double currentPrice;
 public:
  Stock(string symbol, string name);
  string getSymbol() const;
  string getName() const;
  double getPreviousClosingPrice() const;
  double getCurrentPrice() const;
  double changePercent();
  void setPreviousClosingPrice(double);
  void setCurrentPrice(double);
};

#endif

stock.cpp

#include <string>
#include "stock.h"

Stock::Stock(string symbol, string name)
{
  this->symbol = symbol;
  this->name = name;
}

string Stock::getSymbol() const
{
  return symbol;
}

string Stock::getName() const
{
  return name;
}

void Stock::setPreviousClosingPrice(double closing)
{
  previousClosingPrice = closing;
}

void Stock::setCurrentPrice(double current)
{
  currentPrice = current;
}

double Stock::getPreviousClosingPrice() const
{
  return previousClosingPrice;
}

double Stock::getCurrentPrice() const
{
  return currentPrice;
}

double Stock::changePercent() 
{
  return ((currentPrice - previousClosingPrice)/previousClosingPrice) * 100;
}

testStock.cpp

#include <string>
#include <iostream>
#include "string.h"
using namespace std;

int main()
{
  Stock first("aapl", "apple");
  cout << "The stock symbol is " << first.getSymbol() << " and the name is " << first.getName() << endl;
  first.setPreviousClosingPrice(130.0);
  first.setCurrentPrice(145.0);
  Stock second("msft", "microsoft");
  second.setPreviousClosingPrice(30.0);
  second.setCurrentPrice(33.0);
  first.changPercent();
  second.changePercent();
  cout << "The change in percent for " << first.getName << " is " << first.changePercent() << endl;
  cout << "The change in percent for " << second.getName << " " << second.getSymbol() << " is " << second.changePercent() << endl;

  return 0;
}

我肯定它很明顯，但它只是我的第二類程序。

Answer 1

看來您已省略

#include "stock.h"

從您的testStock.cpp 。

Answer 2

編譯器告訴您“未在此范圍內聲明'Stock'” 。 因此，您應該問自己“在哪里宣布“庫存”？ 並且您應該能夠回答： “它在stock.h聲明” 。

並且“為什么編譯器不知道在stock.h聲明了'Stock'？” 因為您還沒有包含它。 因此，正如這里已經提到的那樣， #include "stock.h"是解決方案。

希望您將花費更多的時間閱讀編譯器錯誤/警告，也希望更多的時間嘗試理解它們；）

Answer 3

您只是沒有在主文件中包括"stock.h" ，所以編譯器不知道Stock first意味着什么。

Answer 4

#include "stock.h"

並且您將能夠創建Stock對象，因為它對您的TestStock類是可見的。