Thread: simple error check

I mentioned this above but could you also tell me what is wrong if I print this in my main function. So if anything besides new, list or rev is written as a command an error is printed.

Code:

else {  //if any command entered besides these 3
 printf("Not valid command"); //ERROR CHECK #1
}

Oh I didn't see Click_Here's reply thank you to the both of you. here is my attempt at indenting the code properly

Code:

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


#define SIZE 200 /*the maximum size of strings*/
#define MAX_CMD_LEN 10/*the maximum size of a command*/


void getString( char* );
void printString (const char *);
void reverseString (const char *str, char *reverse);


int main(void)
{
char command[MAX_CMD_LEN];
char string[SIZE] = "";
char *p;
char newstr[SIZE];
char reverse[SIZE];
int flag=1;
 
 do {
    printf("cmd> ");

if(fgets(command,  MAX_CMD_LEN, stdin) != NULL){
      if((p = strchr( command, '\n')) != NULL)
            *p = '\0';
                                                                          }

if(strcmp(command ,"new")==0) {
      getString(string);
                                               }


else if(strcmp(command, "list")==0) {
      printString(string);
                                                    }

else if(strcmp(command, "rev")==0) {
      reverseString(string, reverse);
                                                     }
else {  //if any command entered besides these 3
         printf("Not valid command"); //ERROR CHECK #1
     }


}

while (flag==1);

return 0;
}


void getString(char *string)
{
  printf("Please enter your string");
  fgets(string, SIZE, stdin);
}
void printString(const char *string)
{
  if (string && string[0])
    {
      printf("\n\nHere is the text you entered:\n%s\n", string);
    }
  else
    {
      printf("No string entered");
    }
}

void reverseString(const char *string, char *reverse)
{
int len =0, i, j =0;
if (string && string[0])
    {
  while(string[len])
    len++;
  for(i=len-1;i>=0;i--)
    {
      reverse[j]=string[i];
      j++;
    }
  reverse[j] = '\0';
  printf("%s", reverse);
}
  else  {
    printf("No string entered");
  }
}

So if the user writes new and then just presses enter. I would want the program to consider this also empty. How do I make the program ignore the enter sign. I know this is a simple loop i just kind of forgot it.

Thanks guys!

But thats only so everytime I press enter cmd> comes up
if I write "new" press enter then write "list" I don't get invalied command because the program reads the enter sign. But if I run the program and write "list" then I get invalid command.
so should I do another strchr after every command?

Originally Posted by kiwi101

if I write "new" press enter then write "list" I don't get invalied command because the program reads the enter sign. But if I run the program and write "list" then I get invalid command.

Your description doesn't match the program's behaviour. If I run the code from post #20 and follow your instructions I get the following output (my input in green):

Code:

$ ./test
cmd> new<ENTER>
Please enter your stringlist
cmd> ^C
$ ./test
cmd> list
No string enteredcmd> ^C

In the first case when I enter "new" + <ENTER> I get the prompt to enter a new string. After entering "list" the program prompts me for a new command. Why do you want to get an "invalid command" error message in this situation?
In the second case I don't get "invalid command" but "No string entered".

Could you please describe more accurately your problems.

Bye, Andreas

hey im not sure if this is the right forum. I'm writing a program that simulates the game of Nim basically it goes between user and computer and each have a choice to take away a number from a set counter this happens until one is forced to pick the last number. my problem is with error checking against letter input i already error checked against wrong number input

Code:

..

 
		{
			 printf("\n\nYour turn\n");
			


		
		do										// do while loop for foreign number inputs

		 { 
				
				
				
				printf("\n\n please make a selection between 1 and 3 to take away from counter\n\n");
				scanf_s("%d",&take);
				

				
				system("cls");

	     }while ((take < 1) || (take > 3));
		 
				printf("\n\n you picked %d to be taken away from the counter\n\n", take);
				counters = counters - take;
			    printf("\n There is %d counters left",counters);


		
				if (counters == 1)										// win conditions 
				{
					printf("\n\nyou win\n\n");
		
					fp = fopen(fname,"a");
					time_t now;
					now= time((time_t*)NULL);							// save win time 
					fprintf(fp,"\nuser wins at %s\n",ctime(&now));
					system("pause");
					break;
				}
		}

Originally Posted by filipsons11

hey im not sure if this is the right forum.

This is the right forum, but you should start a new thread rather than highjacking someone else's thread.