获取作为输入到C传递的char *数组的大小++函数 [英] Getting the size of the char* array passed as an input to C++ function

问题描述

我试图传递一个字符指针数组作为从C测试驱动的C ++函数（在C包装用）

I am trying to pass a character pointer array as an input from C test driver to C++ function (available in C wrapper)

char* LowerList[10];
LowerList[0]="abc";
LowerList[1]="def";
LowerList[2]="hij";

当可在C ++侧的元素显示的数值显示为

When available on the C++ side the values displayed for the the element is displayed as

char* LowerList[0]="abc";
LowerList[1]="def";
LowerList[2]="hij";
LowerList[3]=ƒì¶S<\$ UV<35?Ä@
LowerList[34]=ƒ<bad pointer>

我需要传递给我可以用已经拿到了C ++的大小数组的大小
而（LowerList [计数]），但不能这样做，因为垃圾的价值等等。
请让我知道是否有方法可以让我找到字符的正确尺寸* LowerList []通过初始化，内存分配或将其转换为矢量。

I need to get the size of the array passed on to the C++ size which I could have got using while (LowerList[count]) but unable to do so because of the junk value. Please let me know if any way I can find the correct size of the char* LowerList[] by initialising ,memory allocation or converting it to vector.

修正上述code为错字误差

Corrected the above code for typo error

下面是我的一些给我到目前为止的建议意见：

Here are my comments on some of the suggestions given to me so far:

1）传递数组的大小作为一个参数作为一个良好的我的方案。2）转换为载体的限制需要的大小可用3）哨兵值在哪个位置，我需要补充。如前所述，我试图处理这样一个场景，用户传递价值3这导致failure.I没有关于限制的方式C的用户我的C ++包装用他的C测试驱动程序的任何控制权。

1) Pass the size of the array as a parameter as well- A limitation for my scenario .2) Conversion to the vector need the size to be available 3) Sentinel value at which position I need to add . As stated earlier I am trying to handle a scenario where the user pass the value as 3 which leads to the failure.I don't have any control on restricting the way C user my C++ wrapper with his C test driver.

推荐答案

该指针 LowerList [3] 到 LowerList [9] 都是未初始化的，如果我没有记错。你总是可以只使用NULL作为一个哨兵值，要么明确指定，或做这样的事情：

The pointers LowerList[3] through LowerList[9] are all uninitialized, if I'm not mistaken. You could always just use NULL as a sentinel value, and either assign it explicitly or do something like this:

char* LowerList[10] = { "abc", "def", "hij" };

这应该数组为NULL初始化剩下的三分球。

This should initialize the remaining pointers in the array to NULL.

在回答你的第二个评论：

In response to your second comment:

#define LOWER_LIST_SIZE 10
#define MINIMUM_SIZE 2

#if LOWER_LIST_SIZE < MINIMUM_SIZE
    #error "LOWER_LIST_SIZE must be >= MINIMUM_SIZE"
#endif

char *LowerList[LOWER_LIST_SIZE] = // etc.

或者类似的东西。

Or something like that.

的http://en.wikipedia.org/wiki/C_$p$pprocessor#User-defined_compilation_errors_and_warnings

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