为什么我会收到编译错误“ <variable> 没有在此范围内声明”？

Question

前一段时间，我的第一个C ++程序遇到了一些问题。 基本上，我试图做一个C ++课入门课程，在该课程中教授没有教我们语法。 现在是我的代码：

#include <cstdlib>
#include <ctime>
#include <iostream>
#include <string>


using namespace std;
class Race
{
  public:
     void main()
     {

        executeRace();

        int randomMove()
        {
                srand(time(NULL));
                int randomInt = rand() % 100 + 1;
                return randomInt;
        }

        void executeRace()
        {
                int rabbitPosition = 1;
                int turtlePosition = 1;

                cout << "BANG!!!" << endl << "AND THEY'RE OFF!!!";

                while (rabbitPosition <=70 && turtlePosition <=70)
                {
                        printPositions(rabbitPosition, turtlePosition);

                        turtlePosition = turtleMoveSquares(turtlePosition);
                        rabbitPosition = rabbitMoveSquares(rabbitPosition);
                }

                printWinner(rabbitPosition, turtlePosition);

                tie(rabbitPosition, turtlePosition);
        }

        int turtleMoveSquares(int tPosition)
        {

                int turtleMove = randomMove();

                if(turtleMove >=1 && turtleMove <= 40)
                        tPosition = tPosition + 4;

                if(turtleMove >= 41 && turtleMove <= 50 )
                        tPosition = tPosition - 2;

                if(turtleMove >=51 && turtleMove <=100)
                        tPosition = tPosition + 2;

                if(tPosition < 1)
                        tPosition = 1;

                return tPosition;
        }

        int rabbitMoveSquares(int rabbitPosition)
        {

                int rabbitMove = randomMove();

                if(rabbitMove >=1 && rabbitMove <= 25)
                        rabbitPosition = rabbitPosition;

                if(rabbitMove >=26 && rabbitMove <= 55)
                        rabbitPosition = rabbitPosition + 10;

                if(rabbitMove >=56 && rabbitMove <=60)
                        rabbitPosition = rabbitPosition - 15;

                if(rabbitMove >=61 && rabbitMove <= 90)
                        rabbitPosition = rabbitPosition + 5;

                if(rabbitMove >=90 && rabbitMove <=100)
                        rabbitPosition = rabbitPosition - 3;

                if(rabbitPosition < 1)
                        rabbitPosition = 1;

                return rabbitPosition;
        }

        void printPositions(int rabbitPositions, int turtlePositions)
        {
                int turtleCount;
                int rabbitCount;
                int endCount;

                if(rabbitPositions == turtlePositions && rabbitPositions != 1)
                {
                        turtleCount = 1;

                        while(turtleCount < turtlePositions)
                        {
                                cout << "-";
                                turtleCount = turtleCount+1;
                        }
                        cout << "OUCH!";
                }

                else
                {
                        turtleCount = 1;
                        rabbitCount = 1;
                        endCount=1;

                        if(turtlePositions < rabbitPositions)
                        {
                                while(turtleCount < turtlePositions)
                                {
                                        cout <<  "-";
                                                turtleCount = turtleCount+1;
                                }
                                cout << "T";

                                while(rabbitCount < (rabbitPositions - turtlePositions))
                                {
                                        cout <<  "-";
                                        rabbitCount = rabbitCount+1;
                                }
                                cout << "H";

                        }

                        if(rabbitPositions < turtlePositions)
                        {
                                while(rabbitCount < rabbitPositions)
                                {
                                        cout << "-";
                                                rabbitCount = rabbitCount+1;
                                }
                                cout << "H";

                                while(turtleCount < (turtlePositions - rabbitPositions))
                                {
                                        cout << "-";
                                        turtleCount = turtleCount+1;
                                }
                                cout << "T";

                                cout << "\n";
                        }
                }
        }

        void printWinner(int rabbitPosition, int turtlePosition)
        {
                if(turtlePosition >= 70 && rabbitPosition < 70)
                {
                        cout << "TORTOISE WINS!!! YAY!!!\n";
                }
                else if(rabbitPosition >=70 && turtlePosition < 70)
                {
                        cout << "Hare wins. Yuch.\n";
                }
                else if(rabbitPosition >=70 && turtlePosition >=70)
                {
                        cout << "It's a tie\n";
                }
        }

        void tie(int turtlePosition, int rabbitPosition)
        {
                if(rabbitPosition >=70 && turtlePosition >=70)
                        executeRace();
        }

    }
};



int main()
{
  Race race;
  race.main();
  return EXIT_SUCCESS;
}

这是我的编译错误：

uxb3% g++ o- Race Race.cc
g++: o-: No such file or directory
g++: Race: No such file or directory
Race.cc: In member function 'void Race::main()':
Race.cc:14: error: 'executeRace' was not declared in this scope
Race.cc:17: error: a function-definition is not allowed here before '{' token
Race.cc:24: error: a function-definition is not allowed here before '{' token
Race.cc:44: error: a function-definition is not allowed here before '{' token
Race.cc:64: error: a function-definition is not allowed here before '{' token
Race.cc:90: error: a function-definition is not allowed here before '{' token
Race.cc:153: error: a function-definition is not allowed here before '{' token
Race.cc:169: error: a function-definition is not allowed here before '{' token

抱歉让您困扰我，但这是我的第一次，现在我非常沮丧和痴迷。

Answer 1

您的函数 *中不能有函数 。

您可能想要这样：

#include <cstdlib>
#include <ctime>
#include <iostream>
#include <string>


using namespace std;
class Race
{
  public:
    int randomMove()
    {
            srand(time(NULL));
            int randomInt = rand() % 100 + 1;
            return randomInt;
    }

    void executeRace()
    {
            int rabbitPosition = 1;
            int turtlePosition = 1;

            cout << "BANG!!!" << endl << "AND THEY'RE OFF!!!";

            while (rabbitPosition <=70 && turtlePosition <=70)
            {
                    printPositions(rabbitPosition, turtlePosition);

                    turtlePosition = turtleMoveSquares(turtlePosition);
                    rabbitPosition = rabbitMoveSquares(rabbitPosition);
            }

            printWinner(rabbitPosition, turtlePosition);

            tie(rabbitPosition, turtlePosition);
    }

    int turtleMoveSquares(int tPosition)
    {

            int turtleMove = randomMove();

            if(turtleMove >=1 && turtleMove <= 40)
                    tPosition = tPosition + 4;

            if(turtleMove >= 41 && turtleMove <= 50 )
                    tPosition = tPosition - 2;

            if(turtleMove >=51 && turtleMove <=100)
                    tPosition = tPosition + 2;

            if(tPosition < 1)
                    tPosition = 1;

            return tPosition;
    }

    int rabbitMoveSquares(int rabbitPosition)
    {

            int rabbitMove = randomMove();

            if(rabbitMove >=1 && rabbitMove <= 25)
                    rabbitPosition = rabbitPosition;

            if(rabbitMove >=26 && rabbitMove <= 55)
                    rabbitPosition = rabbitPosition + 10;

            if(rabbitMove >=56 && rabbitMove <=60)
                    rabbitPosition = rabbitPosition - 15;

            if(rabbitMove >=61 && rabbitMove <= 90)
                    rabbitPosition = rabbitPosition + 5;

            if(rabbitMove >=90 && rabbitMove <=100)
                    rabbitPosition = rabbitPosition - 3;

            if(rabbitPosition < 1)
                    rabbitPosition = 1;

            return rabbitPosition;
    }

    void printPositions(int rabbitPositions, int turtlePositions)
    {
            int turtleCount;
            int rabbitCount;
            int endCount;

            if(rabbitPositions == turtlePositions && rabbitPositions != 1)
            {
                    turtleCount = 1;

                    while(turtleCount < turtlePositions)
                    {
                            cout << "-";
                            turtleCount = turtleCount+1;
                    }
                    cout << "OUCH!";
            }

            else
            {
                    turtleCount = 1;
                    rabbitCount = 1;
                    endCount=1;

                    if(turtlePositions < rabbitPositions)
                    {
                            while(turtleCount < turtlePositions)
                            {
                                    cout <<  "-";
                                            turtleCount = turtleCount+1;
                            }
                            cout << "T";

                            while(rabbitCount < (rabbitPositions - turtlePositions))
                            {
                                    cout <<  "-";
                                    rabbitCount = rabbitCount+1;
                            }
                            cout << "H";

                    }

                    if(rabbitPositions < turtlePositions)
                    {
                            while(rabbitCount < rabbitPositions)
                            {
                                    cout << "-";
                                            rabbitCount = rabbitCount+1;
                            }
                            cout << "H";

                            while(turtleCount < (turtlePositions - rabbitPositions))
                            {
                                    cout << "-";
                                    turtleCount = turtleCount+1;
                            }
                            cout << "T";

                            cout << "\n";
                    }
            }
    }

    void printWinner(int rabbitPosition, int turtlePosition)
    {
            if(turtlePosition >= 70 && rabbitPosition < 70)
            {
                    cout << "TORTOISE WINS!!! YAY!!!\n";
            }
            else if(rabbitPosition >=70 && turtlePosition < 70)
            {
                    cout << "Hare wins. Yuch.\n";
            }
            else if(rabbitPosition >=70 && turtlePosition >=70)
            {
                    cout << "It's a tie\n";
            }
    }

    void tie(int turtlePosition, int rabbitPosition)
    {
            if(rabbitPosition >=70 && turtlePosition >=70)
                    executeRace();
    }
};

int main()
{
  Race race;
  race.executeRace();
  return EXIT_SUCCESS;
}

*当然，除非处理诸如演算之类的高级语言！

Answer 2

编译器选项：

g++ -o Race Race.cc

您还需要在Race :: main函数中声明函数

class Race
{
  public:
     void main()
     {

        executeRace();
     } // <----- add this

Answer 3

我认为您应该使用gcc -o ...而不是gcc o- ...

其次，您不能使用C ++中的函数定义函数。

将另一个函数定义移到类void main() ：特别是，您需要将int main()之前的倒数第二大括号移到int randomMove()之前。

Answer 4

您想拉出Race中定义的main（）函数中包含的各种函数（在其花括号内）。

选择它们，Ctrl-X（剪切），移到main（）声明Ctrl-V（粘贴）上方。 重新格式化。 重新编译。