command line arguments question

Hey guys i need to check that exatcly 4 arguments are entered via the command line but i if i pass more or only 3 command line arguments it runs when i want it to sto executing.

And would the if statements == NULL be a good way of checking whether the files exist and if not the case exit the program?

Could someone double check if iv done these correctly?

Code:

int commandLineArguments(int argc, char **argv) 
{   
    /* makes a local copy of argc and **argv */

 
   FILE *customer, *stock, *logfile; 
   
    /* declares a pointer to each file*/

    /* test if 4 arguments exist including the exucutable*/

   if(argc !=4) 
   {
     printf("please enter 3 cmd arguments!\n");
     return 1;  
     /* stop pocessing*/
   }

    /* attempt to open and read arg 1*/

   customer = fopen(argv[1], "r");

    /* check if custome.csv exists*/

   if(customer ==NULL)
   {
     printf("cannot open %s for reading\n", argv[1]);
     return 1;  
     /* can't go on*/
   }

     /* try to open stock.csv and read it*/

   stock = fopen(argv[2], "r");
  
     /* if stock.csv does not exist error*/
   
   if(stock == NULL)
   {
     printf("cannot open %s for reading\n",argv[2]);
     return 1;  

     /* stop processing*/
   }

     /* open logfile for reading */  
 
   logfile = fopen(argv[3], "r");

     /* check if logfile exists*/

   if(logfile == NULL)
   {
     printf("cannot open %s for reading\n", argv[3]);
     return 1;  
 
     /* stop processing*/
   }
   
     /* close all files */

     /* checking for closing file errors */

   if(fclose(customer)!=0 || fclose(stock) !=0 || fclose(logfile) !=0)
   {
      fprintf(stderr, "Error in closing files\n");
   }

   return 0;

    
}

Code:

if(argc !=5)  // for 4 arguments ( argv[0] is the name of the executable )

and yes to check if the FILE * returned by fopen() is NULL is normal
Kurt

Code:

int commandLineArguments(int argc, char **argv)

main()?