sprintf with float?

Actually I'm not able to get the correct ouput, formating a float number, not knowing what's going wrong:

(no problems when using int, DWORD  and strings)

#include <stdio.h>

void func(void)

{

char c[25];

float f = 2.5;

sprintf(c, "%5.2f", f );.

}

expected output: "   2.50"

but I get always "-..0" (or anything else what makes no sense)

If tried several variants but I never get a correct result. May be I link a wrong lib or is there any additional type cast necessary?

Any help very appreciated! Thank you very much.

Best regards

Ralph