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DeveloperX
202192397
Joined: 04 May 2003
Posts: 1626
Location: Decatur, IL, USA
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 Posted: Wed Oct 08, 2008 12:16 pm Post subject: (need help) C/C++ void pointers and string array issues |
[quote] |
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Okay I have been using too many other languages recently and I cannot remember a few things regarding C/C++. hopefully there is someone here who can give me a shove in the right direction. :)
I have a need to pass an array of C strings to a function for processing.
My code does not work, and I'm unfortunately both too tired, and too out of practice to find the problem.
The setup is here
| Code: |
SetFunc(&Demo::TestFunction);
char* test[] =
{
(char*)"This is",
(char*)"a more",
(char*)"complicated",
(char*)"test",
(char*)"function."
};
CallFunc(test);
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and the TestFunction source is currently this
| Code: |
void Demo::TestFunction(void* args)
{
printf("This is a test.\n");
if (args)
{
char** str = (char**)args;
for (int i = 0; i < sizeof(str) / sizeof(char*); i++)
{
printf("argument %4d: %s\n", i, str[i]);
}
printf("\n");
}
}
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*sighs*
I feel really shitty having to ask for help with this..so be kind :P
_________________
Principal Software Architect
Rambling Indie Games, LLC
See my professional portfolio
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DeveloperX
202192397
Joined: 04 May 2003
Posts: 1626
Location: Decatur, IL, USA
|
| Posted: Wed Oct 08, 2008 8:51 pm Post subject: |
[quote] |
|
okay, after rethinking the problem, I decided to try again.
I got it this time. My solution involves a new struct.
| Code: |
typedef struct TextChunk_Type
{
unsigned int chunkSize;
char** chunkData;
} TextChunk, *TextChunkPtr;
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and here is the main setup code
| Code: |
SetFunc(&Demo::TestFunction);
char* test[] =
{
(char*)"This is",
(char*)"a more",
(char*)"complicated",
(char*)"test",
(char*)"function."
};
TextChunk chunk;
chunk.chunkSize = sizeof(test) / sizeof(char*);
chunk.chunkData = test;
CallFunc((void*)&chunk);
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and the new TestFunction:
| Code: |
void Demo::TestFunction(void* args)
{
printf("This is a test.\n");
if (args)
{
TextChunk* chunk = (TextChunk*)args;
char** str = chunk->chunkData;
for (int i = 0; i < chunk->chunkSize; i++)
{
printf("argument %4d: %s\n", i, str[i]);
}
printf("\n");
}
}
|
see any better ways outside of using any STL code?
Let me know.
_________________
Principal Software Architect
Rambling Indie Games, LLC
See my professional portfolio
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RedSlash
Mage
Joined: 12 May 2005
Posts: 331
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| Posted: Thu Oct 09, 2008 12:43 am Post subject: |
[quote] |
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Another common method to do passing variable argument arrays is to use NULL as a end of items indicator. e.g.
| Code: |
char* test[] =
{
(char*)"This is",
(char*)"a more",
(char*)"complicated",
(char*)"test",
(char*)"function.",
NULL // <----- indicates end of items
};
|
Your code knows when to stop iterating when it reaches the NULL pointer. This works well when the number of items cannot be determined at compile time.
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