错误（不兼容类型）初始化结构阵列时， [英] Error (incompatible types) when initialising struct array

问题描述

我读过这一些类似的问题，但我仍然无法看到我要去哪里错了。

我的malloc的指针和，似乎工作不错，但我得到这一行的错误（不兼容类型）：

  canArray [I] =（TinCan *）malloc的（的sizeof（TinCan））
 

下面是完整的code：

  typedef结构TinCan
{
    INT日期;
    INT时间;
} 锡罐;诠释的main（）
{
    INT I;
    TinCan * canArray =的malloc（10 * sizeof的（TinCan））;    对于（i = 0; I＆LT; 9;我++）
    {
        canArray [I] =（TinCan *）malloc的（的sizeof（TinCan））;
    }
}
 

解决方案

猜你有一个 typedef结构{...} TinCan; 的地方，那么在这里：

  TinCan * canArray =的malloc（10 * sizeof的（TinCan））;
 

您有10 TinCan 结构足够的空间，但在这里：

  canArray [I] =（TinCan *）malloc的（的sizeof（TinCan））;
 

您正试图分配给另一个 TinCan 结构的空间。

你想要的：

1. TinCan 组成的数组？如果是这样，你不需要循环 - 空间已被分配，当你问 10 * sizeof的（TinCan）




2. 指针数组为 TinCan 结构？如果是这样，第一行更改为：

     TinCan ** canArray =的malloc（10 * sizeof的（canArray [0]））;
    

   和保持循环。

---

一些一般性的评论：

• 您不需要 malloc的前投（）通话 - 看 - 的我投malloc的结果？




• 这是很好的做法是使用的sizeof（varname的[0]），而不是的sizeof（类型名称） ，以避免（或作出更明显）愚蠢的错误。




• 通过电流回路code，您将离开最后一个 TinCan 未初始化 - 你创建的 canArray 10项，但只初始化其中9 I＆LT; 9 。更改为 I＆LT; 10 ，或额外的信用，换出既为的#define NUMBER_OF_CANS 10

I've read some similar questions to this but I still can't see where I'm going wrong.

I malloc the pointers and that seems to work OK, but I get an error (incompatible types) on this line:

canArray [i] = (TinCan *) malloc(sizeof(TinCan))

Here is the complete code:

typedef struct TinCan
{
    int date;
    int time;
} TinCan;

int main ()
{
    int i;
    TinCan *canArray = malloc(10 * sizeof(TinCan));

    for (i =0; i < 9; i++ )
    {
        canArray [i] = (TinCan *) malloc(sizeof(TinCan));
    }
}

解决方案

Guessing that you have a typedef struct {...} TinCan; somewhere, then here:

TinCan *canArray = malloc(10 * sizeof(TinCan));

You have enough space for 10 TinCan structures, but here:

canArray [i] = (TinCan *) malloc(sizeof(TinCan));

You are trying to allocate space for another TinCan struct.

Do you want:

1. An array of TinCans? If so, you don't need the loop - the space has already been allocated when you asked for 10 * sizeof(TinCan)

2. An array of pointers to TinCan structs? If so, change the first line to:

   TinCan **canArray = malloc(10 * sizeof(canArray[0]));
   

   and keep the loop.

---

Some general comments:

• You don't need the cast before the malloc() call - see - Do I cast the result of malloc?

• It's good practice to use sizeof(varname[0]) rather than sizeof(typename), to avoid (or make more obvious) silly mistakes.

• With the current loop code, you will leave the last TinCan uninitialised - you're creating 10 entries in canArray, but only initialising 9 of them with i < 9. Change that to i < 10, or for extra credit, swap out both for a #define NUMBER_OF_CANS 10

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