How to stop processing static const unsigned char * const tab[][]

Hi, I have this code:

Code:

---

static const unsigned char *const Msgs[1][16] =
        {
                {
                        "Please", "go to the", "user menu", "- tanks -",
                        "",                "",                "",                "",
                        "",                "",                "",                "",
                        "",                "",                "",                ""
                }
        };
.
.
.
void fun(void)
{
    unsigned char i;

    for (i = 0; Msgs[0][i]; i++)
        {
        printf("%s", (unsigned char *)Msgs[0][i]);
        }
}

---

I don't know do I aproach this problem correctly, but thing is I want to stop 'for loop' when there is nothing else to display. In fact Msgs[][] is much bigger and sometimes is has one string to display and sometimes 10, 15 etc. How can I detect end of data?

Code:

---

    for (i = 0; Msgs[0][i][0]; i++)
        {
        printf("%s", (unsigned char *)Msgs[0][i]);
        }

---

would break the loop when the string is "".

Or, if you change your "" to NULL, you could use the code you originally wrote.

Edit: Or just remove all of the "" bits, that will set the value to NULL by default [Pedantery: except for machines where NULL is not the same as a pointer with all bits set to zero - but I think those are extremely rare anyways]

--
Mats

You can either store the number of elements or append a terminating null pointer.

And how can I get pointer to Msgs[][] and check that instead of Msgs[][][0] (btw that works fine). I'd like to use point as I have Msgs2 as well :) so just extra code to do something like Ptr=Msgs2 after I foud Msgs[][][0]==NULL or Ptr==NULL.

Quote:

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Originally Posted by nenpa8lo

And how can I get pointer to Msgs[][] and check that instead of Msgs[][][0] (btw that works fine). I'd like to use point as I have Msgs2 as well :) so just extra code to do something like Ptr=Msgs2 after I foud Msgs[][][0]==NULL or Ptr==NULL.

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Do what matsp said, remove all the "" bits, and then assign the pointer:

Code:

---

unsigned char * cPtr;

for(i = 0; cPtr = Msgs[0][i]; i++)
    printf("%s", cPtr);

---

Quote:

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Originally Posted by IceDane

Do what matsp said, remove all the "" bits, and then assign the pointer:

Code:

---

unsigned char * cPtr;

for(i = 0; cPtr = Msgs[0][i]; i++)
    printf("%s", cPtr);

---

---

Why do you need a pointer? Yes, I agree that it avoids indexing the array twice, but the compiler probably does that anyways...

--
Mats

Final looks like this:

Code:

---

static const unsigned char *const Msgs[1][16] =
        {
                {
                        "Please", "go to the", "user menu", "- tanks -",
                        "",                "",                "",                "",
                        "",                "",                "",                "",
                        "",                "",                "",                ""
                },
                {...},  /* More msgs here */
                {...},  /* And even more */
                {...}
        };
.
.
.
void DisplayMsg(unsigned int MsgNum)
{
    unsigned char i;

    for (i = 0; *Msgs[MsgNum][i]; i++)
        {
        printf("%s", (unsigned char *)Msgs[MsgNum][i]);
        }
}

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BTW NULL doesn't compile when repleacing "". I use IAR compiler for 16bit embedded microcontroller H8.

Quote:

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Originally Posted by matsp

Why do you need a pointer? Yes, I agree that it avoids indexing the array twice, but the compiler probably does that anyways...

--
Mats

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Thought that was what he was asking. He says something about a pointer to Msgs.