Thread: Validate digit or char!?

char department;
int done=0;

do
{
printf("\nEnter Department:");
scanf("%s",&department);

if(isdigit(department))
{
if(department<1 || department>9)
printf("\nError\n");
else
{
fprintf(fpold,"%s\n",department);
done=1;
}
}
else
{
printf("\nError (digit only)\n");
}
}while(!done);

The above code is a part from my program to get data for a stock report. My department is meant for a digit between 1 and 9. Is the way I did correct? And, the above code will print Error if I enter a number between 1 and 9. Is there any other way to validate the user input data so that department only take digit between 1 and 9?

Thanks in advance.

>if(isdigit(department))
Looks good to me

>if(department<1 || department>9)
That should be if(department<'0' || department>'9')
but another way would be if(!isdigit(department))
or just use an else since if the first test is true then it is a digit and otherwise it's not so you can print the error.

I tried. Adding a single quote (') to 0 and 9 doesn't work. Windows will said that I have performed an illegal operation when I key in a digit.

Please help!

Thanks in advance.

Here's the working code, I changed the fprintf to printf so that I could debug so you will need to change that back.

Code:

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

int main(void){
    char department; 
    int done=0; 

    do{ 
        printf("\nEnter Department:"); 
        scanf("%c",&department); 

        if(isdigit(department)){ 
            if(department <= '1' || department >= '9') 
                printf("\nError\n"); 
            else{ 
                printf("%c\n",department); 
                done=1; 
            } 
        }else 
            printf("\nError (digit only)\n");
    }while(!done);

    return EXIT_SUCCESS;
}

-Prelude

Mr Prelude! The code you wrote will printf 8 if I enter 89!
Is there any better way to validate the data rather than using isdigit? All I want is o prevent user from keying char and a digit outside 1 and 9...

Thanks in advance.

Okay, then what you want requires a totally different plan. You need to manually parse each element of an array and see if it's a digit, if it is then you print it and if it isn't you break. I've written a little template for you to use, edit it however you need to to get the proper results.

Code:

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

int main(void){
    char department[10];
    int done = 0, i = 0; 

    while(!done){ 
        printf("\nEnter Department:"); 
        fgets(department, sizeof(department), stdin); 

        while(isdigit(department[i])){
            printf("%c",department[i]);
            ++i;
        }
        printf("\n");
        done = 1;
    }

    return EXIT_SUCCESS;
}

-Prelude

hey are you from TARC? perlude ?

What is TARC?

-Prelude

Thanks Prelude! I got it already!
I added another line so that it will print Error messsage when the user key in digit <0 || >9

Thanks so much!