Thread: Work in progress

Hi the below code is not finished and please excusee the usage of gets() and getch() I will change these in due course. I compiled the below code and saw and error with an array subsript I have never seen before.

invalid use of array with unspecified bounds

I have marked on the program where the error lies.

Code:

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

#define EMPLOYEE_ARRAY_SIZE 10
#define SALES_ARRAY_SIZE 10

/*function prototype*/
void companyName ( void );
void inputEmployeeNames ( char[] );
void inputSalesFigures ( char[], int, char[][] );
void sortAndDisplayResults(char[], int, char[][], int, float[] );

/*main function - begins program execution -----------------------------------*/
int main ( void )
{
   companyName();

   getch(); /*freeze console output window*/

   return 0; /*return value from int main*/
}

/*function to input company namw*/
void companyName ( void )
{
   char nameOfCompany[ 80 ];

   printf("Enter company name: ");
   gets( nameOfCompany );

   inputEmployeeNames ( nameOfCompany );
}

/*function to read in the employee names*/
void inputEmployeeNames ( char nmofcmp[] )
{
   int i;
   char names[ EMPLOYEE_ARRAY_SIZE ][ 50 ];

   printf("\n\nEnter the 10 employee names: ");

   for ( i = 0; i < EMPLOYEE_ARRAY_SIZE; i++ )
   {
      gets( names[ i ]);
   }

   inputSalesFigures ( nmofcmp, EMPLOYEE_ARRAY_SIZE, names );
}

/*function to read in the sales figures*/
void inputSalesFigures ( char nmofcmp[], int size, char nameArray[][] )
{
   int i;
   float sales[ SALES_ARRAY_SIZE ];

   printf("\n\nEnter 10 sales figures for the month: ");

   for ( i = 0; i < SALES_ARRAY_SIZE; i++ )
   {
      scanf("%f", &sales[ i ]);
   }

   sortAndDisplayResults ( nmofcmp, EMPLOYEE_ARRAY_SIZE, nameArray, SALES_ARRAY_SIZE, sales);
}

/*function to sort arrays into order and display results
  in tabular format*/
void sortAndDisplayResults ( char nmofcmp[], int size, char nameArray[][], int sizeb, float sal[])
{
   int i, j;

   printf("\n\nCompany Name: %s", nmofcmp);

   /*sort names*/
    qsort(( char* ) nameArray, size,  ( *nameArray ), strcmp );

   /*sort values*/
   for ( i = 0; i < sizeb -1; i++ )
   {
      for ( j = 0; j < sizeb -1 -i; j++ )
         if ( sal[ j + 1 ] < sal[ j ] )
         {
            int tmp = sal[ j ];
            sal[ j ] = sal[ j + 1 ];
            sal[ j + 1 ] = tmp;
         }
   }

   /*display results*/
   printf("\n\nSALES MAN\tTOTAL MADE\n\n");

   for ( i = 0; i < size; i++ )
   {
      printf("%s\n", nameArray[ i ]);  // ERROR ON THIS LINE
   }

   printf("\n\n");

   for ( i = 0; i < sizeb; i++ )
   {
      printf("%.2f\n", sal[ i ]);
   }
}

As I have said anything else wrong I will fix myself, but that was the only error my C compiler found at this time and im confused by its meaning. Any help apprecioated. I thought it would be best to post all the code as the error may link to somthing I have done previously.

> qsort(( char* ) nameArray, size, ( *nameArray ), strcmp );
You need sizeof(*nameArray) for the third argument:

Code:

    qsort(nameArray, size,  sizeof *nameArray, strcmp );

1)

I think you are getting this error message because the compiler don't know which element correspond to nameArray[i] since nameArray is declared as a 2D char array (in your function sortAndDisplayResults).

So, what you should do, is to take this

Code:

void sortAndDisplayResults ( char nmofcmp[], int size, char nameArray[][], int sizeb, float sal[])

and modify it to this

Code:

void sortAndDisplayResults ( char nmofcmp[], int size, char nameArray[][50], int sizeb, float sal[])

But using magic number like this is NOT recommended so you should define some constant. Could looks like this

Code:

#define LENGTH 50
...
void inputEmployeeNames ( char nmofcmp[] )
{
   int i;
   char names[ EMPLOYEE_ARRAY_SIZE ][ LENGTH+1 ];
   ...
}
...
void sortAndDisplayResults ( char nmofcmp[], int size, char nameArray[][LENGTH+1], int sizeb, float sal[])
{
   ...
}

2)

try changing the function prototype (and of course the function itself later) to something like:

Code:

void sortAndDisplayResults(char[], int, char**, int, float[] );

In fact this won't solve the problem. A 2D array (ex.: char foo[][X]) isn't the same thing as an array of pointer (ex.: char *foo[] or char **foo, even if the later isn't a real array of pointer but a pointer on a pointer but they have one point in common; they can be used the same way).

Example

Code:

char foo[10][15];
//foo[1][2] is at adress foo + (1 * 15) + 2

Code:

char **foo;
//foo[1][2], apart from being memory we shouldn't acces, is at adress *(foo + 1) + 2

I don't know if it's clear. It can be a bit confusing. And i'm not 100% sure that i'm right.

Foxman, a flat array of strings (which is what char *foo[] is) can be expressed as char **foo, there is no difference other than a syntactic one. Really, even if you did supply the first dimension's size, it is still an array of strings where the length of the longest string is specified. The type char** is a compatible one.

I can't really see where such an example is used in the code that you provided, so here is something I threw together that demonstrates how to sort strings.

Code:

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

int cstr_cmp( const void *s, const void *t )
{
  const char **u = ( const char** )s, **v = ( const char** )t;
  return strcmp( *u, *v );
}

int main( void )
{
  char *names[] = 
  {
    "Anne", "Berry", "Josh", "Preston",
    "Carl", "John", "Jacob", "David",
  }; 
  size_t k, n = sizeof names / sizeof names[0];

  qsort( names, n, sizeof( char* ), cstr_cmp );

  for ( k = 0; k < n; k++ )
    puts( names[k] );

  return 0;
}

I hope that you find this informative, swgh.

Sorry for not replying before I had some personal business but iv read all the replies and il implment your help in my program. Thanks so much I appreciate all the help given