Celsius to Fahrenheit program wont work right.. (ANSI C)

Im writing a program in C that will convert Celsius to Fahrenheit. When I use int to declare my fahrenheit and celsius numbers, my program runs fine.. but when I use floating-point to do it, it gives me some really WEIRD numbers.. heres my program and the log results.. someone help me.. I want to start writing programs in Cocoa and I cant until I master C and OBJ C..

#include <stdio.h>

int main (int argc, const char * argv[]) {

float fahr, celsius;
int lower, upper, step;

lower = -18;
upper = 149;
step = 18;

celsius = lower;
while (celsius <= upper) {
fahr = (9.0/5.0) * (celsius+32.0);
printf ("%d\t%d\n", celsius, fahr);
celsius = celsius + step;
}
return 0;
}

Log:
0 -1070465024
0 0
0 1077018624
0 1078067200
0 1078657024
0 1079115776
0 1079410688
0 1079705600
0 1080000512
0 1080164352

Message was edited by: Fios89