Put Integer Pointer into Array

Question

I tried to put the Ptr at the end of the frame in C.

void myFunction(uint8_t * Ptr)
{
 uint8_t frame[] = {0x1, 0x2, 0x3, *Ptr}
}

int _main()
{
 myFunction("Hello");
}

in this solution I put only the H of "Hello" into frame[4] because of the 8 bit.

After that I tried

    strcat((char*)frame, (char*) StateTxtPtr);

but it didn't work.

The solution should look like this: frame = {0x1, 0x2, 0x3, "H", "E", "L", "L", "O"}

Thanks for your help!

SOLUTION **

void myFunction(uint8_t * Ptr, uint32_t TxtSize)
{
 uint8_t frame[25] = {0x1, 0x2, 0x3, *Ptr}
 memcpy(&frame[3], Ptr, TxtSize); 
}

int _main()
{
 uint32_t TxtSize = strlen((char *)&txt[i][0]);
 myFunction("Hello", TxtSize);
}

And why do you use {0x1, 0x2, 0x3, *Ptr} instead of {0x1, 0x2, 0x3, Ptr}? — enedil
– enedil, Commented Jan 17, 2014 at 16:07
frame is an array whose length is determined at compile time. As yourself how the compiler can do that, and meet your needs. — David Heffernan
– David Heffernan, Commented Jan 17, 2014 at 16:08
@enedil That wouldn't work at all, it wouldn't even compile. — unwind
– unwind, Commented Jan 17, 2014 at 16:08
If "Hello" is passed as a char *, what is going to happen trying to pick it up as a uint8_t * in the function? Do you pass in a pointer to a long enough space to hold all the data? (a single 64 bit integer should be enough, but what are you doing with an array?) I'm concerned about the { } constant array -- will it be updated with Ptr or *Ptr at run time? — Phil Perry
– Phil Perry, Commented Jan 17, 2014 at 16:14

unwind · Accepted Answer · 2014-01-17 16:08:03Z

6

Your question doesn't make any sense.

You probably want something like this:

uint8_t frame[8] = { 1, 2, 3 };

memcpy(frame + 3, "Hello", 5);

Note that frame must have room for the characters, and that memcpy() is being used to avoid writing the '\0'-terminator that strings have.

answered Jan 17, 2014 at 16:08

unwind

402k64 gold badges492 silver badges620 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Put Integer Pointer into Array

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related