Using strtox for word generator ,-CodePudding

I'm trying to create word generator in C and found Segmentation Fault message.

gdb output :

_GI___strtok_r (
    s=0x562d88201188 "some text without comma", 
    delim=0x562d8820117f " ", save_ptr=0x7f570a47aa68 <olds>) at strtok_r.c:72

code with strtox function :

    char **words = malloc(sizeof(char *) * NUM_WORDS);
    int num_words = 0;
    char *save_ptr;
    char *word = strtok(text, " ");
    while (word != NULL) {

    // Strip leading and trailing whitespace
      while (isspace(*word)) {
        word  ;
      }
      int len = strlen(word);
      while (len > 0 && isspace(word[len - 1])) {
        len--;
      }

    // Allocate memory for the word and copy it using strdup()
      words[num_words] = strdup(word);

    // Move to the next word
      num_words  ;
      word = strtok(NULL, " ");
    }

how to use function with an indeterminate number of words in text?

CodePudding user response：

Can't believe someone finally asked for this!

You may want to add verification that realloc() hasn't returned a NULL.

In brief, the string is chopped on the delimiters provided to strtok() while realloc() is used to grow an array of pointers to each of those segments.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main() {
    char buf[] = "Once upon a time there lived a beautiful princess.", *p = buf;
    char **t = NULL; size_t sz = sizeof *t;
    int n = 0;

    while(!!(t=realloc(t,(n 1)*sz))&&!!(t[n]=strtok(p," .\n"))) p=NULL, n  ;

    for( int i = 0; i < n; i   )
        puts( t[i] );

    free( t );

    return 0;
}

Once
upon
a
time
there
lived
a
beautiful
princess

EDIT
Then there is the extension that can handle multiple input lines:

int main() {
    char *buf[] = { "Once upon a time\n", "there lived\n", " a beautiful princess.\n" };
    char **t = NULL; size_t sz = sizeof *t;
    int n = 0;

    for( int ln = 0; ln < sizeof buf/sizeof buf[0]; ln   ) {
        char *p = buf[ln];
        while(!!(t=realloc(t,(n 1)*sz))&&!!(t[n]=strtok(p," .\n"))) p=NULL, n  ;
    }

    for( int i = 0; i < n; i   )
        puts( t[i] );

    free( t );

    return 0;
}
/* Output same as shown above */

Put the strtok() as the parameter to strdup() and you've got yourself something that will preserve words while using a single line input buffer.