string array conversion

问题

I have the following code:

char *array1[3] = 
{
    "hello",
    "world",
    "there."
};

struct locator_t
{
    char **t;
    int len;
} locator[2] =
{
    {
        array1,
        10
    }
};

It compiles OK with "gcc -Wall -ansi -pedantic". But with another toolchain (Rowley), it complains about

warning: initialization from incompatible pointer type

on the line where char **t is. Is this indeed illegal code or is it OK?

Thanks for all the answer. I now know where my problem was. However, it raises a new question:

string array initialisation

回答1:

Seems perfectly legal to me; char *[3] decays to char **, so the assignment should be valid.

Neither GCC 4.4.5 nor CLang 1.1 complains.

回答2:

Although in practice array1 should decay to a pointer of type char **, its real type is in fact char *[3], hence the warning.

To suppress the warning, you could try casting it explicitly:

...
(char **) array1;
...

回答3:

array1 is (char *)[3], which is semantically different from char **, although in the assignment it should be gracefully degraded to a char **

回答4:

Pointers and arrays and only compatible in static scope. In global scope a pointer and an array are not the same, mixing the two will result in undefined behavior. So in my opinion, the warning is correct.

Try putting:

extern char *array1[3] = 
{
    "hello",
    "world",
    "there."
};

in one module and:

extern char **array1;

struct locator_t
{
    char **t;
    int len;
} locator[2] =
{
    {
        array1,
        10
    }
};

in another, compile and link. (I haven't tried it…) I would expect things to go wrong...

来源：https://stackoverflow.com/questions/7834294/string-array-conversion

标签

ansi-c