gcc c error: expected ')' before numeric constant

Question

Hi I have been trying to port LWIP to a new arm device. When compiling the code i get the error message:

"lwip/lwip-1.4.0/src/include/lwip/memp_std.h:35:23: error: expected ')' before numeric constant"

When I go to this file this and below this several similar macros is what I find on that line:

LWIP_MEMPOOL(RAW_PCB, MEMP_NUM_RAW_PCB,         sizeof(struct raw_pcb),        "RAW_PCB")

If I remove the need for this macro with a define to deactivate the RAW functionality the error moves to the next LWIP_MEMPOL() macro.

The define it seems to want to put a ')' in front of is defined as this:

#define MEMP_NUM_RAW_PCB          1

The RAW_PCB is not defined but is "combined with MEMP_" to create an element in an enum.

I have tried to complie the whole ting with the -E option to get human redable object files and see if i can find any open '(' around the areas where MEMP_RAW_PCB apears and the substitution of MEMP_NUM_RAW_PCB to 1 but I have not found any by manual inspection yet.

Are there any suggestions on what can be going on here or what more I can do or look for to find the cause of the error?

I should maybe add that so far I don't call on any of the LWIP code from main() or any of the functions used in main().

Answer 1

I solved it with:

#ifndef MEMP_STD_H_ 
#define MEMP_STD_H_

... // memp_std.h codes ...

#endif //#ifndef MEMP_STD_H_

Answer 2

The error suggests you have unbalanced parentheses. The code you have provided thus far does not indicate where this problem is, but since ) is expected, it probably means the error is actually in the lines of code preceding the one you have shown.

Examine the code preceding the line you have shown (perhaps after using gcc -E) to check to see if all the parentheses are balanced.

Answer 3

If you're defining it with the dash-D option, it will generate the 1 by default, e.g.:

gcc -D 'MAX(A,B) ((A) < (B)? (B) : (A))' ...

Generates:

#define MAX(A,B) ((A) < (B)? (B) : (A)) 1

And you get the error: expected ‘)’ before numeric constant message at the line where the substitution occurs because of that trailing 1, e.g.:

int maxval = MAX(i,j);
// generates: int maxval = ((i) < (j)? (j) : (i)) 1;

Conversely, if you use the assignment operator to explicitly define the value, it will generate it the way you expected. E.g.:

int maxval = MAX(i,j);
// generates: int maxval = ((i) < (j)? (j) : (i));