Sort pointer to pointer

Question

I'm trying to sort an array of strings that is implemented using a pointer to a pointer. The code I am using is:

void sort(){
  char** names;
  for(int i = 1; i < size; i++){
    int k = i;
    while((strcmp(names[k],names[k-1]) < 0) && (k > 0)){
      char* temp;
      temp = names[k];
      names[k] = names[k-1];
      names[k-1] = temp;
      k--;
    }
  }
}

names is already initialized and filled with 7 names in another method. I get a seg fault at this line

 names[k] = names[k-1];
 names[k-1] = temp;

but I'm not sure why exactly. I get the seg fault after the first iteration of the while loop, and k is decremented to 0. It never returns to the for loop to increment i and k again. Can someone explain why I am getting the seg fault and how to fix it?

Answer 1

(strcmp(names[k],names[k-1]) < 0) && (k > 0) is wrong. The correct form is (k > 0) && (strcmp(names[k],names[k-1]) < 0)

The sequence matters because names[k-1] is unsafe to read when k is zero. && always computes its left operand first and only computes its right operand when the left is true