Thread: Segmentation fault, how come?

There's not enough code to diagnose your problem. I don't even see how the facit array and the matchArray are related.

Could be something in readMatchStats or another function called within the test_readMatchStats function that handles memory poorly. You may think it's working fine as long as the facit array has no more than 4 elements but the real problem lies elsewhere and you simply happen to get an error once you do put more than 4 elements into facit. Show the code for readMatchStats and any other of your functions called within test_readMatchStats... and probably the code for the rest of test_readMatchStats itself as well.

Code:

match_t *readMatchStats(char *fileName) {

    char *lineStart;
    int arrayIndex;
    int matchIndex;
    double *ptr;
    FILE *dataFile;
    char *token;
    char *line = alloca(sizeof(char) * READ_BUFFER_SIZE);
    match_t *matchArray = xmalloc(sizeof(match_t) * 13);

    dataFile = fopen(fileName, "r");
    
    while (fgets(line, READ_BUFFER_SIZE, dataFile) != NULL) {
        lineStart = strchr(line, ';');
        lineStart = lineStart == NULL ? line : lineStart + 1;
        charReplace(line, '#', '\0', 1);
        if (!strlen(lineStart)) continue;
        token = strtok(lineStart, " ");
        for (matchIndex = 0; matchIndex < 3; matchIndex ++) {
            if (!strIsFloat(token)) {
                error(1, 0, "datafile parsing error -- expected float");
            }
            if (!matchIndex) ptr = &matchArray[arrayIndex].home;
            else if (matchIndex == 1) ptr = &matchArray[arrayIndex].draw;
            else ptr = &matchArray[arrayIndex].away;

            *ptr = strtod(token, NULL);
            token = strtok(NULL, " ");
        }
        
        arrayIndex ++;
    }

    fclose(dataFile);

    return matchArray;
    
}

Code:

void test_readMatchStats() {
    
    int c;
    match_t *matchArray;
    match_t facit[] = {
        {0.11, 0.12, 0.13},
        {0.21, 0.22, 0.23},
        {0.31, 0.32, 0.33},
        {0.41, 0.42, 0.43},
        {0.51, 0.52, 0.53},
    };
    matchArray = readMatchStats("test.txt");

    /*for (c = 0; c < 13; c ++) {
        assert(facit[c].home == array[c].home);
        assert(facit[c].draw == array[c].draw);
        assert(facit[c].away == array[c].away);
    }*/

}

EDIT: (I forgot...)

Code:

void *xmalloc(size_t size) {

    void *ptr;
    
    if ((ptr = malloc(size)) == NULL) error(1, errno, NULL);
    
    return ptr;

}

Originally Posted by Fader_Berg

I've written a function that reads floating point numbers from a file and put them in a allocated (malloc) match_t array. It works fine so far. But when writing a unit test for it (yes wrong order, I know), strange things happens.

That's only the wrong order if you were intending to do TDD.
Writing unit tests when you think the code is ready is also fine. Sometimes the tests only come to you after you've written the code and you realise that you need to do something to force it down a certain code path during testing.
TDD is definitely cool though.

Originally Posted by rags_to_riches

Code:

match_t *matchArray = xmalloc(sizeof(match_t) * 13);

What's this magic number 13 for?

For now, this function reads 13 matches (and/or 13 rows in the file), that's all. I'll deal with the flexibility later.

EDIT: I haven't a clue, how to debug a program. Guess it's time to figure that out.

Code:

*ptr = strtod(token, NULL);

Is NULL a valid value to be passing to the strtod function? That doesn't look right. A test in my IDE causes an abort when passing NULL.