Reading from a file, atoi() returns zero only on first element

Question

Hi,

I don't understand why atoi() is working for every entry but the first one. I have the following code to parse a simple .csv file:

void ioReadSampleDataUsers(SocialNetwork *social, char *file) {
    FILE *fp = fopen(file, "r");

    if(!fp) {
        perror("fopen");
        exit(EXIT_FAILURE);
    }

    char line[BUFSIZ], *word, *buffer, name[30], address[35];
    int ssn = 0, arg;

    while(fgets(line, BUFSIZ, fp)) {
        line[strlen(line) - 2] = '\0';

        buffer = line;
        arg = 1;

        do {
            word = strsep(&buffer, ";");

            if(word) {
                switch(arg) {
                    case 1:
                        printf("[%s] - (%d)\n", word, atoi(word));
                        ssn = atoi(word);
                        break;
                    case 2:
                        strcpy(name, word);
                        break;
                    case 3:
                        strcpy(address, word);
                        break;
                }

                arg++;
            }
        } while(word);

        userInsert(social, name, address, ssn);
    }

    fclose(fp);
}

And the .csv sample file is this:

900011000;Jon Yang;3761 N. 14th St
900011001;Eugene Huang;2243 W St.
900011002;Ruben Torres;5844 Linden Land
900011003;Christy Zhu;1825 Village Pl.
900011004;Elizabeth Johnson;7553 Harness Circle

But this is the output:

[900011000] - (0)
[900011001] - (900011001)
[900011002] - (900011002)
[900011003] - (900011003)
[900011004] - (900011004)

What am I doing wrong?

Answer 1

I'd guess that your CSV file was saved in UTF-8 format and has a BOM (byte order mark) at the beginning which is confusing atoi. You can verify this by looking at the file in a hex editor, or looking at the first few bytes of word.

A BOM for UTF-8 is three bytes with the values 0xEF, 0xBB, 0xBF.

If possible, save the file as ASCII. If not, add code to detect and skip these bytes.

Answer 2

My guess is that the file starts with a byte order mark. atoi() sees it as non-digits, so returns 0.

if (line[0] == 0xEF && line[1] == 0xBB && line[2] == 0xBF) {
    /* byte order mark is present, so skip it somehow */
}