Problem with If, &&, ||

[Giri]

Hi Guys,

I currently have the below code:

while( (c = getchar()) != EOF)               
        if ( c != -38 && (c < '0' || c > '3') )
            return false; 

I would only like "false" to be returned IF c DOES NOT equal 0,1,2,3 or -38. However when c becomes equal to -38, "false" is being returned...

Can anyone see my error here?

Thank you for your help!!

Kind Regards,

Giri

[oogabooga]

It looks "correct" as far as it goes, but how exactly are you expecting c to become equal to -38?

Remember that c should be declared as an int so that the EOF returned by getchar will be "out of band" (not a representable char). If you've properly declared c as an int then c will never be negative, except when it's EOF. So it should never be -38.

What exactly are you trying to do there?

[Giri]

Hi Oogabooga,

Thanks for that. I realized my mistake - I should have been putting '10' instead of '-38'. I initially put -38 because I noticed that -38 was being printed when a NewLine was encountered.

However, I am now experiencing the problem that after c = getchar() reads a NewLine and then returns to the line,

 while( (c = getchar()) != EOF) 

nothing happens...the loop just appears to freeze...

What I am trying to do is read individual digits from input in the following form:

022302120222
222223111032

Should I perhaps start a new thread about this issue?

Kind Regards,

Giri

[quzah]

 while( (c = getchar()) != EOF) 

nothing happens...the loop just appears to freeze...

Are you actually entering EOF?


Quzah.

[Giri]

Hi Quzah,

I wouldn't have thought so, because the loop freezes after reading the first line of input. It doesn't seem to get to the 2nd line of input.

Kind Regards,

Giri

[iMalc]

You'll need to show a little more code then.

[Giri]

Ok.

This is what I have written so far.

#define MAX_X_DIM 31
#define MAX_Y_DIM 41
int array[MAX_Y_DIM][MAX_X_DIM];

bool get_input(void) {
    int c;
    int column_counter = 0;
    int row_counter = 0;

    while( (c = getchar()) != EOF){               
        if ( c != 10 && (c < '0' || c > '3') )
    		return false;

        if (column_counter > MAX_X_DIM)
        	return false;

        if(c != 10){
        	array[row_counter][column_counter] = c - 48;
        	++column_counter;
        	}
        else if(c == 10){
        	++row_counter;
        	column_counter = 0;
        }

        if (row_counter > MAX_Y_DIM)
        	return false;
     }

         for (int i = 0; i < row_counter; ++i)
              for (int j = 0; j < column_counter; ++j)
              		printf("%d",array[i][j]);



    return true;


  }

Thanks for your help guys.

Kind Regards,

Giri