I'm trying to pass a pointer to a particular structure in an array of
structures. I think I'm doing something wrong!

Here are the structure definitions:

// Define a structure to build a caption line in
struct tCaptionLine{
  uint8_t Text[100];          // allow up to 100 characters per line. Max
is really 32 or so, but they may use <br/> to do more than one per line
  uint8_t HAlign;             // align line to left or right border, or
center it
  float VPosition;            // position of this line
};

// Define a structure to build the caption in
struct tCaption{
  uint32_t SpotNum;  // Spot or caption number
  uint32_t TimeIn;   // How many 4ms periods from start we want to show
this caption
  uint32_t TimeOut;  // How many 4ms periods from start when we want to
stop showing this caption
  uint32_t Duration; // TimeOut minus TimeIn
  uint8_t VAlign;    // Vertical align to Top, Bottom, or Center
  struct tCaptionLine Line[3];     // 3 caption lines
  uint8_t state;     // Used by ParseXml to keep track of where we are in
parsing input
  uint8_t buf[100];  // build strings here in ParseXml
  uint8_t index;     // Where we'll put the next character into buf in
ParseXml
  uint8_t TextLineNum; // which line we're going to put text in to (0..2).
Used in ParseXml
};


Here's an array of the structure:

// Globals
struct tCaption CaptionBuffer[MaxLanguage+1];

Here's a function to initialize each of the structures:

void InitCaptionBuffer(struct tCaption pCaptionBuffer){
// Initializes the buffer, including state, etc.)
  ClearCaptionBuffer(pCaptionBuffer); // clear spot number, time in, out,
duration, alignment, and text
  pCaptionBuffer.state=0;     // initial state
  pCaptionBuffer.buf[0]=0;    // make input buffer empty
  pCaptionBuffer.index=0;     // next location in input buffer to be
filled is zero
  pCaptionBuffer.TextLineNum=0; // First line of text goes in Line[0]
}


And, here's my call of the initialization function:

uint8_t n;
  for(n=0;n<MaxLanguage+1;n++)
    InitCaptionBuffer(CaptionBuffer[n]);



My understanding (which may be wrong) is that array and structure
arguments to functions are passed as pointers to that array or structure
(the address of the start of the array or structure) instead of passing
the entire array or structure (which would be rather large). Running MPLAB
simulator, I'm seeing in the watch window that CaptionBuffer[] starts at
address 0x08b8. Once inside InitCaptionBuffer() I look at the locals
window and see what appears to be a copy of the structure at address
0x17a8. Changes made here do not show up in my original structure.

So... it looks like I'm not understanding something! How do I pass a
pointer to a particular element in an array of structures do I can modify
the structure components?

THANKS!

Harold








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