I am having a problem with calling the win32 function wsprintf. After the call esp is having an incorrect value. So what I do is:
_esp dd ?
.
.
.
mov [_esp],esp
invoke wsprintf,....... (I always have the correct number of parameters)
mov esp,[_esp]

This definitely not a good programming habit. How can I solve the problem in another way? In the reference there is a note that the function uses some strange calling convention. Do you have some ideas?

wsprintf have C calling convention. That means that you have to fix the stack pointer yourself after return. Actually "add esp, sizeOfArguments" is the standard method of doing so. Also in FASM there is "ccall" macro that counts the arguments passed and fixes the stack pointer for you. See it in "include/macro/ccall.inc" from fasmw package.

Regards.

Maybe this is what I should do with *my* problem:
http://board.flatassembler.net/topic.php?t=2026
Could stdcall, comcall, ccall,... help instead of invoke?

Yes, thanks John, I understood many things just by looking at the included macros.