[Programming Pearls] Gerrymandering Problem

[standstand]

I want to start the Gerrymandering problem with memory limitation to 27000, but not 16*16000, so bellow program is for that. However, problems for compilation met. I would say, well, really cannot tell what's wrong in line 22 and 61!
Anyone who can help? Thanks in advance!
---- compilation error:
$ gcc Gerrymandering.c -o Gerrymandering.out
Gerrymandering.c:22: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘setDistrict’
Gerrymandering.c: In function ‘readDistricts’:
Gerrymandering.c:61: error: expected expression before ‘short’

---- source code:

#include <stdio.h>


#define SORTMEMLIMIT     27000 /* (16*1000) */
#define MAXDISTRICT    27000
#define SORTTYPE    short
#define SORTMEMSIZE    (SORTMEMLIMIT/sizeofS(SORTTYPE))
//#define DISTRICTS     ("disricts.txt")
char districtsFile[] = "districts.txt";


int main()
{
    readdistricts(districtsFile);
    return 0;
}




/*
FILE: setDistrict
input:
    district, scope: 1-MAXDISTRICT
*/
bool setDistrict(SORTTYPE districtsBitmap[], int district, int bitmapLimit)
{
    bool success = false;
    if(district >= bitmapLimit)
    {
        printf("ERROR: invalid distict number: %d for limit: %d!\n", district, bitmapLimit);//try __FILE__ __LINE__ later
    }
    else
    {
        int bitPosition = (district-1)%sizeof(SORTTYPE);
        int arrayPosition = (district-1)/sizeof(SORTTYPE);
        SORTTYPE move = 1;
        SORTTYPE setBit = move<<bitPosition;
        
        if(*(districtsBitmap+arrayPosition)&setBit)
        {
            printf("ERROR: district: %d was set already!", district);
        }
        else
        {
            *(districtsBitmap+arrayPosition) |= setBit;
            success = true;
        }
    }


    return success;
}


int readDistricts(const char* districtsFile)
{
    FILE *fpDistricts;
    if(!(fpDistricts = fopen(districtsFile, "r+")))
    {
        return 1;
    }


    int district;
    int counter = 0;
    int failedDistrictCounter = 0;
    SORTTYPE districtsBitmap[SORTMEMSIZE];    


    while( ((++counter)< SORTMEMLIMIT)&&(1==fscanf(fpDistricts, "%d", &district)) )
    {
        if(!setDistrict(districtsBitmap, district,SORTMEMLIMIT))
        {
            failedDistrictCounter++;
        } 
    } 
    fclose(fpDistricts);
    printf("INFO: districts sorting finished. Districts number of failed operation: %d, out of %d\n", failedDistrictCounter, counter);


    return 0;
}

[standstand]

pasted codes, lines are different from what showed in linux. so error line 22 is 26 here, while 61 should be 68.

[Elkvis]

gcc tells me that bool is not a valid type name, unless you have defined or typedef'd it somewhere.

[oogabooga]

Turn up your compiler warnings.


"bool" is not part of C89 and is not defined in C99 unless you include stdbool.h. (Same with true and false.)


The other line demonstrates the dangers of macros. Since they work by textual replacement what you see is NOT what you get. Look at the definition of the macros used on that line. One of them has "sizeofS" in it, which should presumably be "sizeof".


Also, you should put prototypes of your functions before main.

[standstand]

gcc tells me that bool is not a valid type name, unless you have defined or typedef'd it somewhere.

yes, bool is a standard prototype for c. Well, it was just so natural to use bool after working on other languages:P
Thank you

[standstand]

Turn up your compiler warnings.


"bool" is not part of C89 and is not defined in C99 unless you include stdbool.h. (Same with true and false.)


The other line demonstrates the dangers of macros. Since they work by textual replacement what you see is NOT what you get. Look at the definition of the macros used on that line. One of them has "sizeofS" in it, which should presumably be "sizeof".


Also, you should put prototypes of your functions before main.

Hi, problems were solved and they are exactly what you described Except the prototypes part. I also remember that, if a function is invoked before its definition, prototype is needed to be announced. However, magic thing is, with my compilation environment, there's no compilation error reported without the annoucing. Is it strange?
Thank you

[oogabooga]

Hi, problems were solved and they are exactly what you described Except the prototypes part. I also remember that, if a function is invoked before its definition, prototype is needed to be announced. However, magic thing is, with my compilation environment, there's no compilation error reported without the annoucing. Is it strange?
Thank you

If you leave out the prototypes then C89 will assume a return value of int (which is what your functions return) and will assume nothing about the parameters. I believe the C99 standard does not allow you to leave them out, though.


However, you forgo certain kinds of error checking if you leave them out, so it's better to put them in.