Question 38278 in Ubuntu Question posted in
The official Ubuntu documentation can be found here.

strtok() is working correctly on WSL Ubuntu but not on Windows Mingw32

The code below is giving me problems on Windows Mingw32 but not on WSL Ubuntu. The delimiter is (char)32 (space).

while (!feof(f)){
    if(!fgets(line, LINE_LEN, f) || !*line || !strcmp(line, "n")) continue;
    word = strtok(line, &delim);
    printf("xdn");
    while(word){
        //printf("%sn",word);s
        add_item(h,word);
        word = strtok(NULL, &delim);
        wc++;
    }
    lc++;
}

I had tried debugging the code with CLion and the variable ‘line’ is correctly filled with given sentence that contain spaces, therefore strtok should not be returning null on the first iteration, yet it is. CLion Debug

Tags:

3

Answers


  1. Chosen as BEST ANSWER
    0

    Delim only contained the space character and did not contain the character, therefore it crashed.

    EDIT:

    More detailed answer by @Joop Eggen below in comments to this answer:

    strtok's second parameter is a string of delimiters, like " t.", and hence a char delim = ' '; and &delim searches next chars till the string terminator ''.


  2. 0

    Please replace that code with this:

    // FILE *f presumed to be opened for reading
char line[ 1024 ];
int lc = 0, wc = 0;
while( fgets( line, sizeof line, f ) ) {
    for( char *wp = line; ( wp = strtok( wp, " n" ) ) != NULL; wp = NULL ) {
        add_item( h, wp ); // unseen in this question.
        wc++;
    }
    lc++;
}

    Empty lines can be safely loaded into line, and strtok() will deal with them correctly (ie: find no words.)

    Login or Signup to reply.
  3. 0

    The strtok function expects a C string as its second argument (a pointer to a null terminated array of char. delim is presumably defined as char delim = ' '; so &delim is a pointer to char but not a C string because there is a single character and no null terminator. The code has undefined behavior, it may appear to work on some platforms and not on others.

    You should instead use a string " n" or possibly " trn" as the delimiter string.

    Furthermore, you should learn Why is “while( !feof(file) )” always wrong? . The loop should be change to: while (fgets(line, LINE_LEN, f)

    Here is a modified version:

    int parse_file(FILE *f, struct hash_table_t *h) {
    char line[LINE_LEN];
    const char *delim = " trn";
    int wc = 0, lc = 0;

    while (fgets(line, sizeof line, f)) {
        char *p = line;
        char *word;
        while ((word = strtok(p, delim)) != NULL) {
            add_item(h, word);
            wc++;
            p = NULL;
        }
        lc++;
    }
    return wc;
}
    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search