1 #include <stdio.h>
 2 #include <windows.h>
 3 
 4 void usage(int freq_min, int freq_max){
 5   printf("usage: beep.exe frequency duration\n");
 6   printf("  frequency   hertz (values between %d and %d are allowed)\n", freq_min, freq_max);
 7   printf("  duration    milliseconds\n\n");
 8   exit(1);
 9 }
10 
11 int main(int arg, char *argv[], char *envp[]){
12   int freq_min=37, freq_max=20000;
13   if(arg<3) usage(freq_min, freq_max);
14   int freq=atol(argv[1]);
15   int duration=atol(argv[2]);
16   if(freq<freq_min || freq>freq_max || duration<0) usage(freq_min, freq_max);
17   bool beeped=Beep(freq, duration);
18   if(!beeped){
19     printf(" an error occured\n");
20     exit(1);
21   }
22   return 0;
23 }