Unable to properly sort an array of strings

Your program doesn't execute to segmentation fault. (at least when compiled & executed via GCC 7.2 in Ubuntu). However, there are a few points that you might need to focus upon in order to get your sorting part straight.

1. Focus at this line : for (j=0; j<s-i; j++). Here, the final value that j will acquire will be 5. How ? You have declared s as 6 during it's initialization and the minimum value of i is 0. So by default j can range over 0 to 5 (note that j has to be less than s-i, therefore, the for loop won't let it go beyond 5). But how does it affect your logic? Now if the maximum value that j acquires is 5, then maximum of j+1 will be 6. Therefore, when you perform swapping in the extreme end(at j=5), you might end up with a garbage value in your array. You'll notice this fact, as soon as you'll execute your code multiple times. To resolve this issue, simply use for (j=0; j<s-i-1; j++).
2. Now come at the line containing this (strcmp(names[j], names[j+i])>0) statement. Your code says that you're using bubble sort in the descending fashion. Therefore, for that to happen here, you need to have (strcmp(names[j+1], names[j])>0). This will allow you to compare your string at the (j+1)th index to that of jth index. If the string at (j+1)th index is bigger than the one at jth index, then you can go for swapping(since, you want your sorting to be done in descending fashion).

To put the above thoughts into practice, here we go :

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

int main()
{

    char *names[] = {"William","Olivia","Willaim","Olivai","Lily","Lyli"};
    int sums[6] = {58, 48, 58, 48, 30, 30};
    int i, j, s = 6;
    char *temp_char;
    int temp_int;
    for(i=0 ; i < s ; i++){
          for (j=0; j<s-i-1; j++){ //Change 1
              if (sums[j]<sums[j+1]){
                  temp_char = names[j+1];
                  temp_int = sums[j+1];
                  names[j+1] = names[j];
                  sums[j+1] = sums[j];
                  names[j] = temp_char;
                  sums[j] = temp_int;
              }
              if ((sums[j] == sums[j+1]) && (strcmp(names[j+1], names[j])>0)) { //Change 2
                  temp_char = names[j+1];
                  names[j+1] = names[j];
                  names[j] = temp_char;
              }           
          }
    }

    for (i = 0; i<s; i++){
          printf("%d ", sums[i]);
          printf("%s\n", names[i]);
    }

    return 0;
}

A suggestion for your code : Use struct to combine your names and sums array together. Efficiency wise it wouldn't seem like much, but it'll help your code to appear much more cleaner.

SOLUTION:

You are getting the error because of variable j which might cross the index bound.

So, you should check for j < s-i-1; in the inner loop. And also I optimized your code with the isSwapped boolean variable.

CODE:

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

int main()
{

  char *names[] = {"William","Olivia","Willaim","Olivai","Lily","Lyli"};
  int sums[6] = {58, 48, 58, 48, 30, 30};
  int i, j, s = 6;
  char *temp_char;
  int temp_int;
  bool isSwapped; // for optimization
  for(i=0 ; i < s ; i++){
    isSwapped = false;
    for (j=0; j<s-i-1; j++) { 
      // Sort by sum
      if (sums[j]<sums[j+1]){
          temp_char = names[j+1]; temp_int = sums[j+1];
          names[j+1] = names[j]; sums[j+1] = sums[j];
          names[j] = temp_char; sums[j] = temp_int;
          isSwapped = true;
      }
      // Sort by name (only if values of sum is same)
      else if ((sums[j] == sums[j+1]) && (strcmp(names[j+1], names[j])>0)) {
          temp_char = names[j+1];
          names[j+1] = names[j];
          names[j] = temp_char;
          isSwapped = true;
      }
    }
    if (!isSwapped) break;
  }

  for (i = 0; i<s; i++){
    printf("%d ", sums[i]);
    printf("%s\n", names[i]);
  }

  return 0;
}