scanf

[cProgNoob]

I am very new to c programming and dont mean to be wasting anyones time but after trying to use the scanf function I am having some difficulties. I have created much more intracate programs (which isnt hard I know) but i havent used scanf, and I really cant see how this is going wrong.

int main(void){

	int no, valid;
	
	printf("\nHow many would you like?\n\n           ");
	
	if(scanf("%d",&no) != 1){ // Checking to see only one argument has been entered
	
		printf("\nOnly one value.\n");
		return (EXIT_FAILURE);
		
	}
	
	valid = scanf("%d",&no);
	valid = ((valid != 0) && (valid != EOF));
	
	if( !valid ){ // Checking to see the correct data type has been entered
	
		printf("\nMust be an integer.\n");
		return (EXIT_FAILURE);
		
	}	
	
	return (EXIT_SUCCESS);
	
}

The error checks seem to not be working.

when I type in 'a 2 ' it prints 'Only one value' but when I type '2 a' it prints 'Must be an integer'. But in both instances I am expecting 'Only one value' to be printed.

Sorry for such a trivial problem but any help would be much appreciated

Cheers

[Dino]

When you enter '2 a', the first scanf() only sucks in the 2 and leaves the a in the input buffer because scanf() is smart enough (dumb enough?) to stop parsing at the first whitespace it encounters. So the 'a' is left for your second scanf() to pull.

[cProgNoob]

thank u for such a prompt reply, it has been very helpful

[haseth]

You can use flushall(); after your first scanf so that it only reads the first scanf and removes the second one from the buffer.

[laserlight]

You can use flushall(); after your first scanf so that it only reads the first scanf and removes the second one from the buffer.

Unfortunately flushall() does not appear to exist in the C standard library or cProgNoob's code.