Question

我正在尝试运行C ++代码，但我遇到了这个错误

Build started: Project: roman numerals, Configuration: Debug Win32 ------
1>Compiling...
1>Main.cpp
1>c:\users\owner\documents\dark gdk\projects\roman numerals\roman numerals\main.cpp(40) : error C2065: 'number' : undeclared identifier
1>c:\users\owner\documents\dark gdk\projects\roman numerals\roman numerals\main.cpp(40) : fatal error C1903: unable to recover from previous error(s); stopping compilation
1>Build log was saved at "file://c:\Users\Owner\Documents\Dark GDK\Projects\roman numerals\roman numerals\Debug\BuildLog.htm"
1>roman numerals - 2 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

这是代码：

#include "DarkGDK.h"
const int I = 1;
const int II = 2;
const int III = 3;
const int IV = 4;
const int V = 5;

void setup();
void input();
void display();
void cleanup();
void DarkGDK()
{
      setup();
      input();
      cleanup();
}
void setup()
{
       dbSetWindowOff();
       dbLoadBitmap("C:\\Users\\Owners\\Pictures\\DeVry\\roman numeral 1.bmp",I);
       dbLoadBitmap("C:\\Users\\Owners\\Pictures\\DeVry\\roman numeral 2.bmp",II);
       dbLoadBitmap("C:\\Users\\Owners\\Pictures\\DeVry\\roman numeral 3.bmp",III);
       dbLoadBitmap("C:\\Users\\Owners\\Pictures\\DeVry\\roamn numeral 4.bmp",IV);
       dbLoadBitmap("C:\\Users\\Owners\\Pictures\\DeVry\\roamn numeral 5.bmp",V);
}

void input()
{
       dbPrint("enter a number1 to 5 to see its roman numeral");
       int number = 0;
       number = atoi(dbInput());
       display();
}

void display ()
{
       while (number !=6)
       {
              switch (number)
              {
              case 1:
                   dbCopyBitmap(I,0);
                   break;
              case 2:
                   dbCopyBitmap(II,0);
                   break;
              case 3:
                   dbCopyBitmap(III,0);
                  break;
             case 4:
                  dbCopyBitmap(IV,0);
                 break;
             case 5:
                  dbCopyBitmap(V,0);
                  break;
             case 6:
                  dbPrint("ending program");
                  dbWait(2000);
             default:
                  dbPrint("not a valid choice, only numbers 1 through 5 work");
                 dbPrint("try again");
              }
       }
}

void cleanup ()
{
       dbDeleteImage(I);
       dbDeleteImage(II);
       dbDeleteImage(III);
       dbDeleteImage(IV);
       dbDeleteImage(V);
}

Answer 1

void input()
{
       dbPrint("enter a number1 to 5 to see its roman numeral");
       int number = 0;
       number = atoi(dbInput());
       display();
}

void display ()
{
       while (number !=6)
       {
        // ...

display函数在其访问范围内没有名为number的变量。 number的范围仅在input函数中，不能传播到它依次调用的函数。

Answer 2

您可能希望将number参数传递给display函数。

        int number = 0;
        number = atoi(dbInput());
-       display();
+       display(number);
 }

-void display ()
+void display (int number)
 {
        while (number !=6)
        {

Answer 3

您在number函数中使用display()变量。这里无法进入。

Answer 4

在Input（）函数中声明变量'number'，这意味着它只存在于此函数中。您正试图从另一个函数（第40行）使用它，编译器无法看到它。你需要做的是在代码顶部的任何函数之外放置数字（const int declerations是）：

e.g

int number;

void input()
{
       dbPrint("enter a number1 to 5 to see its roman numeral");
       number = atoi(dbInput()); //Set the value of number here
       display();
}

void display ()
{
       while (number !=6) //use number here
       {
           ...
       }
}

使用#include“DarkGDK.h”编译C ++程序时出错

4 个答案: