qsort turns all values of array to null - c

Question

I have a program which reads in the lines of a text file and stores them in linesArr, I have also defined a function compFunc which takes two strings as inputs, makes copies of them and converts the copies to lowercase before returning the value of strcmp(copy1, copy2). I am trying to use this function to sort linesArr into alphabetical order with qsort(linesArr, size, 255, compFunc. But the values in the array turn from {"Bob", "James", "Alice"} to {(null), (null), (null)}.
This is how linesArr is initialised.
char **linesArr = (char**)malloc(size*sizeof(char));
for (int i = 0; i < size; i++) {
linesArr[i] = (char*)malloc(255*sizeof(char));
}
And it it filled with values from the text using the file pointer fp
for (int i = 0; i < size; i++) {
fgets(line, 255, fp);
strcpy(linesArr[i], line);
}
Why is qsort deleting the values in the array?

Answer 1

For starters this memory allocation
char **linesArr = (char**)malloc(size*sizeof(char));
^^^^^
is incorrect, You need to write
char **linesArr = (char**)malloc(size*sizeof(char *));
^^^^^^
Secondly the call of qsort must look like
qsort(linesArr, size, sizeof( char * ), compFunc);
because the array pointed to by the pointer linesArr is an array of pointers.
Here is a demonstrative program.
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
int compFunc( const void *a, const void *b )
{
const char *s1 = *( const char ** )a;
const char *s2 = *( const char ** )b;
while ( *s1 && tolower( ( unsigned char )*s1 ) == tolower( ( unsigned char )*s2 ) )
{
++s1;
++s2;
}
return tolower( ( unsigned char )*s1 ) - tolower( ( unsigned char )*s2 );
}
int main(void)
{
enum { size = 3, len = 255 };
char **linesArr = malloc( size * sizeof( char * ) );
for ( size_t i = 0; i < size; i++ )
{
linesArr[i] = malloc( len * sizeof( char ) );
}
char line[len];
for ( size_t i = 0; i < size; i++ )
{
fgets( line, sizeof( line ), stdin );
line[ strcspn( line, "\n" ) ] = '\0';
strcpy( linesArr[i], line );
}
qsort( linesArr, size, sizeof( *linesArr ), compFunc );
for ( size_t i = 0; i < size; i++ )
{
puts( linesArr[i] );
}
for ( size_t i = 0; i < size; i++ )
{
free( linesArr[i] );
}
free( linesArr );
return 0;
}
The program output might look like
Bob
James
Alice
Alice
Bob
James