this code to convert pounds to barbados dollars given a constant rate the price cannot go over $100 when i first run it and input a number under 100 it tells me that it is invalid and sometimes i get nothing at all. Can neone tell me why?

/* This Program converts Pounds Sterling to Barbados Dollars*/
# include <stdio.h>

int main ()

	float Pds, Bds; /* Declare Variables*/
	const float Rate =3.75;

	printf("Enter the Price in Pounds Sterling\n"); /*Prompt User*/
	scanf_s("%f", &Pds);

   while(Pds >100);/* finds illegal value*/
    printf("Error your price cannot be greater than $100\n");
	printf("Please Enter another\n");


     printf("Price in Barbados Dollars=%.2f",Bds);

	return 0;


stop using scanf() because it may corrupt the input buffer and leave keys in the keyboard buffer. use fgets() instead

float num;
char buf[16];
// get input from user
// convert to float
num = atof(buf);

Hm did U got corrupted code and your task is to fix it?
No?!?! Ok then just remove ; after while loop.

yeah it was the semi colon, thx a bundle can i ask why it did that tho?

>> while(Pds >100);

that is an infinite loop because of the semicolon at the end. Your program will never stop executing that loop because the value os Pds never changes. This is a common error that everybody counters on occasion due to carelessness.

while ( Pds > 100 ) ; is equivalent to

while ( Pds > 100 )
   // sit back and enjoy baby 

Like Mr. Dragon said the variable which controls the run of your "While " loop never changes and so it goes on for infinity.