My code takes in a series of words as command line arguments and should sort them using qsort. Right now I print out the original Args however when it goes to print the Sorted args I receive a segmentation error. New to C, all advice is appreciated.
#include <stdlib.h>
#include <string.h>
int stringCmp(const void *str1, const void *str2); //Function prototype.
int main (int argc, char *argv[])
{
int i;
char **arr = malloc(argc * sizeof(char *));
printf("Original Args:\n");
for (i = 0; i < argc-1; i++){
arr[i] = argv[i+1];
printf("%s\n",arr[i]);
}
qsort(arr, argc, sizeof *arr, stringCmp);
printf("\nSorted Args:\n");
for (i = 0; i < argc; i++){
printf("%s\n", arr[i]);
}
free (arr);
return 0;
}
int stringCmp(const void *str1, const void *str2)
{
strcmp(str1, str2);
}
Your comparison function isn't returning anything. Also, this function takes the address of the array elements, so what you're actually getting are char * const *, not void *
You want:
int stringCmp(const void *str1, const void *str2)
{
const char * const *s1 = str1;
const char * const *s2 = str2;
return strcmp(*s1, *s2);
}
You're also not passing in the correct number of elements to qsort. It should be argc-1, not argc. The same going for printing the list:
qsort(arr, argc-1, sizeof *arr, stringCmp);
printf("\nSorted Args:\n");
for (i = 0; i < argc-1; i++){
printf("%s\n", arr[i]);
}
For starters you are passing invalid number of elements
qsort(arr, argc, sizeof *arr, stringCmp);
You need to write
qsort(arr, argc - 1, sizeof *arr, stringCmp);
Secondly the function stringCmp returns nothing and uses incorrect arguments in the call of strcmp. It should look like
int stringCmp(const void *str1, const void *str2)
{
return strcmp( *( const char ** )str1, *( const char ** )str2);
}
out by one here too
for (i = 0; i < argc; i++) {
printf("%s\n", arr[i]);
}
should be
for (i = 0; i < argc - 1; i++) {
printf("%s\n", arr[i]);
}