#include <stdio.h>
#include <windows.h>
 
BOOL APIENTRY DllMain (HINSTANCE hInstDLL, DWORD reason, LPVOID reserved) {
 
	BOOL dllSuccess = FALSE;
 
	if (reason == DLL_PROCESS_ATTACH) {
		dllSuccess = MessageBox (NULL, "Funciona! :)", NULL, MB_OK);
	}
 
	return dllSuccess;
}
 
__declspec(dllexport) void __stdcall MyFunction (void) {
 
	printf ("Hello world!\n");
}
 

#include <stdio.h>
#include <windows.h>
 
int main (int argc, char **argv) {
 
	HMODULE hKernel32 = GetModuleHandle ("Kernel32");
	FARPROC lpLoadLib = GetProcAddress (hKernel32, "LoadLibraryA");
 
	HANDLE hThread = CreateThread (NULL, 0, (LPTHREAD_START_ROUTINE) lpLoadLib, (void*) argv[1], 0, NULL);
	WaitForSingleObject (hThread, INFINITE);
 
	DWORD hLibModule=0;
	GetExitCodeThread (hThread, &hLibModule);
	if (!hLibModule) {
		fprintf (stderr, "ERROR: Could not retrieve the module handle.\n");
		return 1;
	}
 
	FARPROC myFunc = GetProcAddress ((void*) hLibModule, "MyFunction");
	if (!myFunc) {
		fprintf (stderr, "ERROR: Could not retrieve the function address.\n");
		return 1;
	}
 
        myFunc();
	CloseHandle (hThread);
	return 0;
}

return ((BACKSLASH | SLASH | COLON | ASTERISK | QUESTION | QUOTES | LESS | GREATER | PIPE) & sym);

a = 4 = ...0100
b = 6 = ...0110
a | b = 4 | 6 = ...0110 = 6

QUESTION=0x10
sym=0x10
QUESTION & sym = 0x10 = 16

#define BACKSLASH 0x0001
#define SLASH     0x0002
#define COLON     0x0004
#define ASTERISK  0x0008
#define QUESTION  0x0010
#define QUOTES    0x0020
#define LESS      0x0040
#define GREATER   0x0080
#define PIPE      0x0100
 
#define NUMSYM 9
 
int is_symbol(int sym) {
 
	int i, symbols[]={BACKSLASH, SLASH, COLON, ASTERISK, QUESTION, QUOTES, LESS, GREATER, PIPE};
 
	for (i=0; i<NUMSYM; i++)
		if (symbols[i]^sym == 0) return 1;
 
	return 0;
}

int is_symbol(int sym) {
 
	return !(BACKSLASH^sym && SLASH^sym && COLON^sym && ASTERISK^sym && QUESTION^sym && QUOTES^sym && LESS^sym && GREATER^sym && PIPE^sym);
}

#include <stdio.h>
 
#define M1 0.25
#define M2 0.10
#define M3 0.05
#define M4 0.01
 
int main() {
 
	int m1, m2, m3, m4;
	float cantidad;
 
	printf("Introduce la cantidad: ");
	scanf("%f", &cantidad);
 
	m1=(int)(cantidad/M1);
	cantidad-=m1*M1;
 
	m2=(int)(cantidad/M2);
	cantidad-=m2*M2;
 
	m3=(int)(cantidad/M3);
	cantidad-=m3*M3;
 
	m4=(int)(cantidad/M4);
	cantidad-=m4*M4;
 
	printf("Monedas de 0.25:\t%d\nMonedas de 0.10:\t%d\nMonedas de 0.05:\t%d\n"
		   "Monedas de 0.01:\t%d\n", m1, m2, m3, m4);
 
	return 0;
}

xiruko:~$ gcc monedas.c -o monedas
xiruko:~$ ./monedas 
Introduce la cantidad: 2.43
Monedas de 0.25:	9
Monedas de 0.10:	1
Monedas de 0.05:	1
Monedas de 0.01:	3
xiruko:~$