Question

I have extracted the “meaning” part of my code (and also replace some line to simplify it).

I have 2 dynamic pointers, one for the current line (extracted from a file) and a second for the current token.
Following this question, Free/delete strtok_r pointer before processing complete string?
I wrote this :

int main(void) {
    int n = 455;  
    char *tok2, *freetok2;
    char *line, *freeline;

    line = freeline = malloc(n*sizeof(*line));
    tok2 = freetok2 = malloc(n*sizeof(*tok2));

    /* content of the file) */
    const char* file_reading =  "coucou/gniagnia/puet/";

    /* reading from the file */
    strcpy(line, file_reading);

    strtok(line, "/");
    /* get the second token of the line */
    tok2 = strtok(NULL, "/");

    fprintf(stdout, "%s \n", tok2); // print gniagnia
    fprintf(stdout, "%s \n", line); // print coucou

    /* free error */
    //free(tok2);

    /* worked, but maybe don't free "everything ?" */
    //free(line);

    free(freetok2);
    free(freeline);

    return 0;
}

But at the end, I’m not sure of what is correct or not, and I find this solution not so elegant (because of using 2 “save variables”.

Is that correct ? Is there some ways to improve it ?
Thanks

Edit: changed my code for this, (and it will handle all the lines of the file)

include <unistd.h>
include <stdlib.h>

int main(void) {
    char *tok2; 
    char *line; 

    /* content of the file) */
    const char* file_reading =  "coucou/gniagnia/puet/";
    const char* file_reading2 =  "blabla/dadada/";

    /* reading from the file */
    line = strdup(file_reading);

    strtok(line, "/");
    /* get the second token of the line */
    tok2 = strtok(NULL, "/");

    printf("%s \n", tok2);
    printf("%s \n", line);

    /* reading from the file */
    line = strdup(file_reading2);

    strtok(line, "/");
    /* get the second token of the line */
    tok2 = strtok(NULL, "/");

    printf("%s \n", tok2);
    printf("%s \n", line);

    free(line);

    return 0;
}

Answer 1

You’re not actually using the memory pointed by freetok2, you don’t need to malloc anything, thus you don’t need the freetok2 variable.

Saying free(line) or free(freeline) is the same in your code so you don’t need the freeline at all.

Another problem is this: malloc(n*sizeof(*line));. You might as well be saying: malloc(n); because sizeof(char) is always 1. But best of all would be:

line = malloc(strlen(file_reading) + 1);
strcpy(line, file_reading);