validation

Hi, can someone tell me what's wrong with this code?

Code:

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        while ((num <= 1) && (num >= 9999)) {
        printf("\n");
        printf("\tinventory number: ");
        scanf("%d", &num);
        if (num <= 1)
        printf("Invalid entry\n");
        printf("Please enter a value greater than or equal to 1\n");
        if (num >= 9999)
        printf("Invalid entry\n");
        printf("Please enter a value less than or equal to 9999");
        }

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I want it to ask for an inventory number until the user enters a number between 1-9999 and give an error message if the number is outside of that range.

Quote:

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can someone tell me what's wrong with this code?

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The most glaring thing is the lack of indentation
Second is that you need a OR and not an AND
Third instead of having two if statements change it to one

Code:

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while ( (num <= 1) || (num >= 9999) )
{
  printf("\n");
  printf("\tinventory number: ");
  scanf("%d", &num);
  if (num <= 1 || num >= 9999)
  {
    printf("Invalid entry\n");
    printf("Please enter a value between 1 and 9999\n");
  }
}

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Thanks man. Can you take a look at this beast?

Code:

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        char ch1 = toupper(cat1);
                char ch2 = toupper(cat2);
                while (toupper(char1, != 'F') && (ch1 != 'N') && (ch2 != 'D') && (ch2 != 'M') && (ch2 != 'N') && (ch2 != 'P') && (ch2 != 'S') && (ch2 != 'A') && (ch2 != 'H'))
                {
                        printf("\tcategory\t: ");
                        while (getchar() != '\n');
                                scanf("%c%c", &cat1, &cat2);

                                if (ch1 == 'F')
                                {
                                        if ((ch2 != 'D') && (ch2 != 'M') && (ch2 != 'N') && (ch2 != 'P') && (ch2 != 'S'))
                                        {
                                                printf("Invalid entry\n");
                                                printf("Second character must be D,M,N,P,or S\n");
                                        }
                                }
                                else if (ch1 == 'N')
                                {
                                        if ((ch2 != 'A') && (ch2 != 'H') && (ch2 != 'M') && (ch2 != 'P') && (ch2 != 'S'))
                                        {
                                                printf("Invalid entry\n");
                                                printf("Second character must be A,H,M,P,or S\n");
                                        }
                                }
                                else {
                                        printf("Invalid entry");
                                        printf("Category must be F or N\n");
                                }
                }

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The first character must be either F or N. If the first character is F, then the second character must be D,M,N,P,or S. If the first character is N, then the second character must be A,H,M,P,or S.

Another method:

Code:

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

void validate(int ch1, int ch2)
{
  switch (ch1)
  {
    case 'F':
      if (strchr("DMNPS", ch2))
      {
        puts("Valid by first choice");
      }
      else
      {
        puts("Invalid by first choice");
      }

      break;

    case 'N':
      if (strchr("DMNPS", ch2))
      {
        puts("Valid by second choice");
      }
      else
      {
        puts("Invalid by second choice");
      }

      break;

    default:
      puts("Not even close");
      break;
  }
}

int main(void)
{
  validate('F', 'Z');
  validate('N', 'M');
  validate('Z', 'Z');
  return(0);
}

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There are many ways to do this... ;)

Code:

---

        while ((num <= 1) && (num >= 9999)) {
        printf("\n");
        printf("\tinventory number: ");
        scanf("%d", &num);
        if (num <= 1)
        printf("Invalid entry\n");
        printf("Please enter a value greater than or equal to 1\n");
        if (num >= 9999)
        printf("Invalid entry\n");
        printf("Please enter a value less than or equal to 9999");
        }

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The evaluation in your while loops wants number less then 1 or a number greater then 9999, but your second if statement will givea validation error if the user selected number is in fact greater than 9999. Isn't this contradicting?

I think you want:

Code:

---

while (num >= 1 && num <= 9999) {

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Hammer, can you briefly explain what your code is doing here?

Code:

---

int main(void)
{
  validate('F', 'Z');
  validate('N', 'M');
  validate('Z', 'Z');
  return(0);
}

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Quote:

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Originally posted by blanny
Hammer, can you briefly explain what your code is doing here?

Code:

---

int main(void)
{
  validate('F', 'Z');
  validate('N', 'M');
  validate('Z', 'Z');
  return(0);
}

---

---

The code is calling the validate function 3 times, to test different scenarios. Normally a validation function would also return a value representing success or failure, but my example is left to simply write out to the screen.

What I provided is a compilable program, have a go at running it yourself, and making alterations to the parameters in the validate() function calls and observe the results.

Here's how I'm trying to implement it:

Code:

---

while (valid != 1)
                {
                        printf("\tcategory\t: ");
                        while (getchar() != '\n');
                                scanf("%c%c", &cat1, &cat2);

                        void validate(int ch1, int ch2)
                        {
                                switch (ch1)
                                {
                                        case 'F':
                                        if (strchr("DMNPS", ch2))
                                {
                                        valid = 1;
                                }
                                else
                                {
                                        puts("Second character must be D,M,N,P,or S");
                                }
                                        break;

                                case 'N':
                                if (strchr("AHMPS", ch2))
                                {
                                        valid = 1;
                                }
                                else
                                {
                                        puts("Second character must be A,H,M,P,or S");
                                }
                                        break;

                                default:
                                        puts("First character must be F or N");

                                        break;
                        }

                        validate(ch1, ch2);
                }

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Quote:

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Posted by OOPboredom
I think you want:

Code:

---

while (num >= 1 && num <= 9999) {

---

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If you re-read the error messages inside the loop you will see that he wants numbers in the range from 1 to 9999 inclusive. Or you can just re-read his first post[qoute]I want it to ask for an inventory number until the user enters a number between 1-9999[/quote]
Now I can make one little change to your loop to make it valid though

Code:

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while ( !(num >= 1 && num <= 9999) ) {

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>>Here's how I'm trying to implement it:
Your layout is wrong, validate() is a complete function and must live outside all other functions. Look at the layout of this summarised version:

Code:

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int validate(char ch1, char ch2)
{
  int valid = 0;
  /*
  * Do validation here
  */
  return valid;
}

int main(void)
{
  char cat1, cat2;
 
  /*
  * read user input here
  */
 
  /*
  * Now call validate()
  */
  if (validate(cat1, cat2) == 1)
  {
    puts ("Yes, its valid");
  }
}

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