如何在c中传递或声明数组成员？

Question

我开发了一个程序，它应该通过以下函数传递双重购买数组的以下成员：

float beverages ()
{              
   char response;
   double purchase [8]= {3.50, 3.80, 3.90, 4.20, 4.00, 4.30, 3.00, 3.10};
   printf("\nEnter your order: ");
   scanf("%c", response);

   if (response == 'l')
   {
      purchase [0];
      printf("You have chosen a Regular Long Black coffee\n");
      printf("that will be %.2f dollars", purchase [0]); 

   }
   else if (response == 'L')
   {
      purchase [1];
      printf("You have chosen a Large Long Black coffee\n");
      printf("that will be %.2f dollars", purchase [1]);

   }
   else if (response == 'f')
   {
      purchase [2];
      printf("You have chosen a Regular Flat White coffee\n");
      printf("that will be %.2f dollars", purchase [2]); 

   }
   else if (response == 'F')
   {
      purchase [3];
      printf ("You have chosen a Large Flat White coffee\n");
      printf("that will be %.2f dollars", purchase [3]); 

   }

   else if (response == 'c')
   {
      purchase [4];
      printf("You have chosen a Regular Cappuccino\n");
      printf("that will be %.2f dollars", purchase [4]);    
   }
   else if (response == 'C')
   {
      purchase [5];
      printf("You have chosen a Large Cappuccino\n");
      printf("that will be %.2f dollars", purchase [5]);        
   }
   else if (response == 't')
   {
      purchase [6];
      printf("You have chosen a Regular Tea\n");
      printf("that will be %.2f dollars", purchase [6]);    
   }
   else  if (response == 'T')
   {
      purchase [7];
      printf("You have chosen a Large Tea\n");
      printf("that will be %.2f dollars", purchase [7]);    
   }

   return purchase[];
}

我在 int main 中有它，比如：

int main()
{
  ...
  printf("MENU!");
  decision (choice);
  purchase [] = beverages();
  ...
  return 0;
}

使用以下代码购买 [] = beverages();似乎有一个问题，编译器说 purchase 是未声明的，并且在 ] 标记之前有一个意想不到的表达式（顺便说一下，错误只在 int main 中）。似乎我没有正确地从函数传递数组或其他什么？我试过添加值 8，例如 purchase[8] = beverages();但随后编译器说 purchase 不是指针或数组。我该如何调试？我只是没有使用正确的语法还是没有正确传递数组？

Answer 1

因为'beverages()'函数想要returndouble array那么你需要像

那样修改

  double * beverages()
     {        
        static double purchase [8]= {3.50, 3.80, 3.90, 4.20, 4.00, 4.30, 3.00, 3.10};
        // Line of code
        return purchase;
     }

main函数中需要修改为

main()
{
   double *purchase = beverages();     
}

beverages() 中定义的变量 purchase 是该函数的局部变量，您无法在 main()

中访问它

Answer 2

数组 purchase 的词法范围在过程 beverages 内。您可以在 main 内部声明它，而不是尝试在 main 外部访问数组。

int main(void) 
{
      double purchase [8]= {3.50, 3.80, 3.90, 4.20, 4.00, 4.30, 3.00, 3.10};
      ... 
      ...
}

现在您可以通过指向过程 beverages 的指针传递数组的地址

void beverages(double *purchase) {

    char response;
    printf("\nEnter your order: ");
    scanf("%c", &response);

    if (response == 'l')
    {
        printf("You have chosen a Regular Long Black coffee\n");
        printf("that will be %.2f dollars", *purchase + 0);

    }
    ...

}

并在main

中调用程序

int main(void)
{

      double purchase [8]= {3.50, 3.80, 3.90, 4.20, 4.00, 4.30, 3.00, 3.10};
;

      beverages(purchase);


}

另外如果你想改变数组的值

*(purchase + i) = value  // where i is index location

如何在c中传递或声明数组成员？

How to pass or declare array members in c?

c

arrays

debugging

parameter-passing