NewB Problem

**djdgr** · 01-27-2002

Ok all please help an OLD VAX Fortran programmer understand why this does not work.
The is idea is to read the command line and parse it so that i can extract a file name to record the data to. Also, i need to be able to get the other arguments to work. This segment of code was copied from a similiar vax fortran program.

input to command line >>>> dr /r grr1.dat /? /p 1 /s 9600

output==>>
recording data to: grr1.dat
port 1
baud rate 9600
at 12:43pm

int main(int argc, char* argv[])
{ int count;
printf("argument count %d \n",argc);
for( count = 0; count < argc; count++ )
{
printf( " argv[%d] %s\n", count, argv[count] );
if ( argv[count] == "/r" )
{
printf("call recording\n");
printf("file %s \n",argv[count+1]);
}
if ( argv[count] == "/?" ) printf("call usage\n");
}

return 0;

**bigtamscot** · 01-27-2002

Quickly read thru your code

spotted this ...

Code:

printf( " argv[%d] %s\n", count, argv[count] ); 
/*should print charcter  %c not string */
printf( " argv[%d] %c\n", count, argv[count] ); 
/*same here */
printf("file %s \n",argv[count+1]); 

printf("file %c \n",argv[count+1]);

**Prelude** · 01-27-2002

Code:

int main(int argc, char* argv[]) 
{  int count; 
   printf("argument count %d \n",argc); 
   for( count = 0; count < argc; count++ ) 
   { 
      printf( " argv[%d] %s\n", count, argv[count] );
      /*Won't work, comparing strings with ==*/ 
      if ( argv[count] == "/r" ) 
      { 
         printf("call recording\n");
         /*I'm assuming the command line arguments 
         **are not interchangeable. If they are this could 
         **choke.
         */ 
         printf("file %s \n",argv[count+1]); 
      }
      /*Comparing strings with == won't work*/ 
      if ( argv[count] == "/?" ) printf("call usage\n"); 
   } 

   return 0;
}

To compare strings you want to use either strcmp or strncmp, == won't work. And make sure that if the command line arguments are interchangeable you test that the next string in argv isn't nothing or calling argv[count + 1] will cause a nasty bug.

bigtamscot:
argv is defined as char *argv[] which means it's an array of pointers to char, aka an array of strings. Using the format key %c for a string constant won't work as expected.

-Prelude

**clu82** · 01-27-2002

Code:

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


int main(int argc, char* argv[])
{
   while (argc--)
   {
      if (!strncmp(argv[argc], "/r", 2))
      {
         printf("data file: %s\n", argv[argc+1]);
      }
      else if (!strncmp(argv[argc], "/p", 2))
      {
         printf("port: %s\n", argv[argc+1]);
      }
      else if (!strncmp(argv[argc], "/s", 2))
      {
         printf("speed: %s\n", argv[argc+1]);
      }
   }		

   return 0;
}

**djdgr** · 01-28-2002

Thank you for help ....

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