break a string into 'first' and 'second' - c

Question

I have read through countless strtok posts, even copied some directly in their entirety into a new int main, but I can't figure out how to create the functions get_first and get_second.
get_first("This is a sentence."); //returns "This"
get_rest("This is a sentence."); //returns "is"
This is what I have so far, I have had nothing but trouble with strtok, but I don't know what else to use.
#include <stdio.h>
#include <string.h>
char * get_first(char * string) {
string = strtok(string, " ");
return string;
}
char * get_second(char * string) {
string = strtok(string, " ");
string = strtok(NULL, " ");
return string;
}
int main(int argc, char * argv[]) {
char * test_string = "This is a sentence.";
char * first = get_first(test_string);
char * second = get_second(test_string);
printf("%s\n", first);
printf("%s\n", second);
}
Getting no faults compiling with gcc -g -Wall, but it always seg faults. I think I have tried every permutation of char c[] and char * c there is.

Answer 1

strtok changes the string. (but String literals are not allowed to change.)
So create a copy.
Do the following:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
char * get_first(const char *string){
char *clone = strdup(string);//create copy, strdup is non standard. malloc and copy.
char *token = strtok(clone, " ");
if(token)
token = strdup(token);
free(clone);
return token;
}
char * get_second(const char *string) {
char *clone = strdup(string);
char *token = strtok(clone, " ");
if(token && (token = strtok(NULL, " ")))
token = strdup(token);
free(clone);
return token;
}
int main(void) {
char * test_string = "This is a sentence.";
char * first = get_first(test_string);
char * second = get_second(test_string);
printf("%s\n", first);
printf("%s\n", second);
free(first);
free(second);
}