exit array

**ct26torr** · 02-13-2003

I have this code I have been working with and I am trying to exit an array if someone enters a zero. I have tried some different things but cant manage to make it work. Is it even possible to do? My code is below.

Code:

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

#define SIZE 10 /* size of array */


int verify (char* value) /* this function will verify the input is a number*/
{
  int iChars = strlen (value);
  int i;

  for (i=0; i<iChars; i++) {
    if (! isdigit (value [i])) {
      return 0; /*Not a number*/
    }
  return 1; /*Is a number*/
  }
}


int main()
{
   int i, arr[SIZE], sum, average;
   char temp[50];

   /* get the numbers */
   printf("Enter up to 10 numbers, to stop entering numbers enter a zero. \n");
   for(i=0; i<SIZE; )
   {
      if(fgets(temp, sizeof(temp), stdin) == NULL) /*make sure there has been input*/
      {
         printf("Please enter a valid number\n");
         return 1;
      }

      if(!verify(temp))
      {
         printf("Invalid input, please try again\n");
      }
      else
      {
         arr[i] = atoi(temp); /*convert char to int */
         ++i; /* next number */
      }
   }
   return 0;
}

**Hammer** · 02-13-2003

>>I am trying to exit an array if someone enters a zero
Do you mean you want to exit the loop, when someone enters zero? If so, just put an if test in the loop somewhere appropriate, and if its true, use the break keyword.

**ct26torr** · 02-13-2003

cool .... thanks. I will give it a try

**ct26torr** · 02-13-2003

This is what I have but it doesn't seem to work.

Code:

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

#define SIZE 10 /* size of array */


int verify (char* value) /* this function will verify the input is a number*/
{
  int iChars = strlen (value);
  int i;

  for (i=0; i<iChars; i++) {
    if (! isdigit (value [i])) {
      return 0; /*Not a number*/
    }
  return 1; /*Is a number*/
  }
}


int main()
{
   int i, arr[SIZE], sum, average;
   char temp[50];

   /* get the numbers */
   printf("Enter up to 10 numbers, to stop entering numbers enter a zero. \n");
   for(i=0; i<SIZE; )
   {
      if(fgets(temp, sizeof(temp), stdin) == NULL) /*make sure there has been input*/
      {
         printf("Please enter a valid number\n");
         return 1;
      }

      if(fgets(temp, sizeof(temp), stdin) == 0) /*exit if zero is entered*/
      {
         printf("Thank you. This program will now stop accepting input.\n");
         break;
      }

      if(!verify(temp)) /*check to see if input is a number*/
      {
         printf("Invalid input, please try again\n");
      }
      else
      {
         arr[i] = atoi(temp); /*convert char to int */
         ++i; /* next number */
      }
   }
   return 0;
}

**Govtcheez** · 02-13-2003

> if(fgets(temp, sizeof(temp), stdin) == 0) /*exit if zero is entered*/

That'll stop if they enter a literal 0. 0 and '0' are different things. Also, you can't compare strings with ==.

**Hammer** · 02-13-2003

Your verify() function is wrong. If you lay it out like this, you can see the problem easier (imho):
Hint: Look at the return statements

Code:

int verify(char *value) /* this function will verify the input is a number*/
{
  int iChars = strlen(value);
  int i;

  for (i = 0; i < iChars; i++)
  {
    if (!isdigit(value[i]))
    {
      return(0);  /*Not a number*/
    }

    return(1);    /*Is a number*/
  }
}

Now, this:
>>if (fgets(temp, sizeof(temp), stdin) == 0)
is good code, but isn't doing what you think it is. fgets() returns a pointer to the array, or NULL if there's an error (or EOF) during input. Don't change this section, leave it in to handle input errors.

Now to the solution for a 0 being entered.

A quick hack would be something like this:
>>if (temp[0] == 0) /*exit if zero is entered*/
but this wouldn't be very good if the user entered 099.

Instead, you can wait until you've been through the verify() function and then test arr[i].
So, after this line:
>>arr[i] = atoi(temp); /*convert char to int */
put this statement:
>>if (arr[i] == 0)
and then whatever you want.

[edit]
Govt: you're off base

**ct26torr** · 02-13-2003

Oh man now I have like 6 errors.

Code:

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

#define SIZE 10 /* size of array */


int verify (char* value) /* this function will verify the input is a number*/
{
  int iChars = strlen (value);
  int i;

  for (i=0; i<iChars; i++) {
    if (! isdigit (value [i])) {
      return 0; /*Not a number*/
    }
  return 1; /*Is a number*/
  }
}


int main()
{
   int i, arr[SIZE], sum, average;
   char temp[50];

   /* get the numbers */
   printf("Enter up to 10 numbers, to stop entering numbers enter a zero. \n");
   for(i=0; i<SIZE; )
   {
      if(fgets(temp, sizeof(temp), stdin) == NULL) /*Handles input errors*/
      {
         printf("Inout invalid, please try again\n");
         return 1;
      }


      }

      if(!verify(temp)) /*check to see if input is a number*/
      {
         printf("Invalid input, please try again\n");
      }
      else
      {
         arr[i] = atoi(temp); /*convert char to int */
		 if (arr[i] == 0) 
			printf("Thank you. This program will now stop accepting input.\n");
			break;
         ++i; /* next number */
      }
   }
   return 0;
}

**Hammer** · 02-13-2003

You still haven't fixed the verify() function.

Here, I've fixed the problems, mainly to do with braces in the wrong place. The code runs now, but it doesn't verify your numbers correctly. I shan't spoil your fun and tell you how to fix it, if you can't work it out, post again. Hint: newline.

Code:

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

#define SIZE  10  /* size of array */

/* */
int verify(char *value) /* this function will verify the input is a number*/
{
  int iChars = strlen(value);
  int i;

  for (i = 0; i < iChars; i++)
  {
    if (!isdigit(value[i]))
    {
      return(0);  /*Not a number*/
    }
  }

  return(1);      /*Is a number*/
}

/* */
int main(void)
{
  int   i, arr[SIZE], sum, average;
  char  temp[50];

  /* get the numbers */
  printf("Enter up to 10 numbers, to stop entering numbers enter a zero. \n");
  for (i = 0; i < SIZE;)
  {
    if (fgets(temp, sizeof(temp), stdin) == NULL) /*Handles input errors*/
    {
      printf("Inout invalid, please try again\n");
      return(1);
    }
    
    if (!verify(temp))      /*check to see if input is a number*/
    {
      printf("Invalid input, please try again\n");
    }
    else
    {
      arr[i] = atoi(temp);  /*convert char to int */
      if (arr[i] == 0)
      {
        printf("Thank you. This program will now stop accepting input.\n");
        break;
      }
      ++i;                  /* next number */
    }
  }

  return(0);
}

**ct26torr** · 02-13-2003

thanks for the help. I will see if I can make it work.

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