Thread: Need help with testing a condition

Hello to all,

For the following code, I want to add a test so that if the user inputs anything that isn't an integer , he/she will receive an error message as opposed to a segmentation fault error which is happening now.

Here is the code:

Code:

else if ((strcmp ( command, "show")) == 0 )
                    {
                        list_num = atoi(strtok(NULL, " \n\t")) ;
                                                                      
                        int x ;
                        int line_count = 1 ;
                                             
                       for(x = 0; x<strlen(loadedSequences[list_num-1].data) ; ++x) // print 60 letters per line.
                            {   
                                if(x==0)
                                    {
                                        printf("%10d",line_count) ;
                                    }
                                if((x%10 == 0))
                                    {
                                        printf(" ") ;
                                    }
                                        
                                if((x%60 == 0) && (x != 0))
                                    {
                                        printf("\n%10d ",(line_count+x)) ;
                                    }
                                 printf("%c", loadedSequences[list_num-1].data[x]) ;
                                 
                            }
                        
                        printf("\n") ;                       
                    }

The code works fine otherwise. Any suggestions would be great.

What's wrong with

Code:

if (list_num != 0)
  /* print things */
else
  /* print error */

?

thanks