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c_user
Joined: 19 May 2010
Posts: 9
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| Pointer to array pointer to structures - compile error help |
 Posted: Sat Jun 12, 2010 3:55 pm |
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I have the following structure:
| Code: | typedef struct font_struct
{
int16 font_length;
int16 font_width;
} font_select; |
I then add an array of pointers to this structure, which compiles correctly:
| Code: | | font_select *screen_ptr[3]; |
Now, I want to add a point to this array of pointers, and am using the following construction:
| Code: | | font_select (*(*scr_ptr)[]); |
The compiler issues an error report:
| Code: | Executing: "C:\Program Files\PICC\Ccsc.exe" +FH "FT430.c" +DF +LN +T +A +M +Z +Y=9 +EA
*** Error 58 "FT430.c" Line 72(17,18): Expecting a close paren
*** Error 43 "FT430.c" Line 72(19,20): Expecting a declaration
*** Error 48 "FT430.c" Line 72(21,28): Expecting a (
*** Error 43 "FT430.c" Line 72(29,30): Expecting a declaration
*** Error 43 "FT430.c" Line 72(30,31): Expecting a declaration
*** Error 43 "FT430.c" Line 72(31,32): Expecting a declaration
*** Error 12 "FT430.c" Line 79(10,17): Undefined identifier scr_ptr
7 Errors, 0 Warnings.
Halting build on first failure as requested.
BUILD FAILED: Sat Jun 12 14:41:59 2010 |
What am I doing wrong? |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sat Jun 12, 2010 11:40 pm |
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The method used in the test program shown below appears to work.
Here's the program output (in MPLAB simulator):
| Quote: |
Pointers to structures:
0005
0009
000d
Pointer to array of pointers:
0011
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.Sym file:
| Quote: |
005-010 fs
011-016 screen_ptr
017-018 scr_ptr
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Test program. Compiled with vs. 4.107:
| Code: |
#include <18F452.h>
#fuses XT,NOWDT,PUT,BROWNOUT,NOLVP
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS)
typedef struct font_struct
{
int16 font_length;
int16 font_width;
}font_select, *p_fs;
// Declare an array of 3 of the above structures.
font_select fs[3];
// Declare an array of pointers to the 3 structures,
// and initialize it the start address of each
// structure.
p_fs screen_ptr[3] = {
&fs[0].font_length,
&fs[1].font_length,
&fs[2].font_length
};
// Declare a pointer to the array of pointers above
// and initialize it.
p_fs *scr_ptr = screen_ptr;
//======================================
void main(void)
{
int8 i;
printf("Pointers to structures: \r");
for(i=0; i < 3; i++)
printf("%lx \r", (int16)screen_ptr[i]);
printf("Pointer to array of pointers: \r");
printf("%lx \r", (int16)scr_ptr);
while(1);
}
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c_user
Joined: 19 May 2010
Posts: 9
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| Posted: Sun Jun 13, 2010 10:48 pm |
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| Thanks for giving me a solution. I see why it works. But I am still curious whether my C declaration was wrong, or whether the compiler can't handle it. If you know, I'd appreciate hearing your analysis. |
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