Thread: Characters in If Statements

I was just writing some more for my program and I tried to to this:

Code:

	printf("Are you sure you want to clear the database? (Y or N) ");
	fgets(buff,sizeof(buff),stdin);
	sscanf(buff,"%c", &ques);
	if((ques !='y)' || (ques !='Y'))

But even if I type Y , it does what is in the if statement's brackets. So how do you compare characters correctly?

Using sscanf for this is a bit of an overkill. Try something like this

Code:

 #include <stdio.h>
 #include <ctype.h>
 
 int main(void)
 {
   char buff[BUFSIZ];
   
   printf("Are you sure you want to clear the database? (Y or N) ");
 
   if (fgets(buff, sizeof(buff), stdin) == NULL)
   {
     /* Handle input error */
   }
 
   if (toupper(buff[0]) == 'Y')
   {
     /* User entered y or Y */
     puts ("thanks!");
   }
   
   return 0;
 }

Originally Posted by Padawan

I was just writing some more for my program and I tried to to this:

Code:

	printf("Are you sure you want to clear the database? (Y or N) ");
	fgets(buff,sizeof(buff),stdin);
	sscanf(buff,"%c", &ques);
	if((ques !='y)' || (ques !='Y'))

But even if I type Y , it does what is in the if statement's brackets. So how do you compare characters correctly?

The below code should work...

Code:

	printf("Are you sure you want to clear the database? (Y or N) ");
	fgets(buff,sizeof(buff),stdin);
	sscanf(buff,"%c", &ques);
	if((ques !='y)' && (ques !='Y'))

I too used to get confused with this logic before.. the reason is we think in English...(some ppl might say we have to)... think about the logic...


if((ques !='y)' || (ques !='Y'))


if you enter y the first part of the sattement is false and since its and the second part of the statement is true and the condition is executed.......

ahhh dint notice that error in his code.. cust and paste is evil

Originally Posted by nonpuz

how about ditching fgets altogether and just use:

Code:

int c;

if ( ( c=toupper( getchar() ) ) != 'Y')

Because if you don't handle the newline that getchar kindly leaves behind then any further input will probably have issues. Of course, you could use a common hack to remove extraneous characters, but fgets is a little more elegant.