Sleep program for half a second in C on Linux-CodePudding

I just can't find a way to sleep my program or just make it wait for a set amount of miliseconds, I tried sleep() but it only works for full seconds, usleep() is giving implicit declaration error and correcting it to sleep(), nanosleep() also only pauses it for full seconds.

while(1){
        wclear(win);
        box(win, 0, 0);
        mvwprintw(win, 0, anim, "Snake");
        wrefresh(win);

        sleep(500);

        if(intro == 3){
            if(anim < 53) anim  ;
            else intro--;
        }
        if(intro == 2){
            if(anim > 2) anim--;
            else intro--;
        }
        if(intro == 1){
            if(anim < 23) anim  ;
            else intro--;
        }
        if(intro == 0) break;
    }

All I want is to make a smooth little animation, but no matter what library I use or what kind of sleep function I use, it will either do full seconds which is too long, or 0 seconds (so nothing), or throw errors.

CodePudding user response：

Here are some ideas to explore why usleep isn't working out. select is another popular way to delay for periods of time.

#include <unistd.h>
int main( )
{
  int i;
  for ( i = 0 ; i < 10 ; i   ) usleep(100000);
  return 0;
}

Also, try using the compiler to reveal where unistd.h is coming from, like this for gcc

gcc -H main.c 
. /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/unistd.h
. . . MORE . . .

Another helping idea is to output the preprocessor output like this:

gcc -E main.c 

# 1 "main.c"
# 1 "<built-in>" 1
# 1 "<built-in>" 3
# 370 "<built-in>" 3
# 1 "<command line>" 1
# 1 "<built-in>" 2
# 1 "main.c" 2
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/unistd.h" 1 3 4
# 71 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/unistd.h" 3 4

. . . MORE . . .

Here is some code that uses select to create a timeout.

#include <unistd.h>
#include <stdio.h>
int main( )
{
  fd_set set;
  struct timeval timeout;
  FD_ZERO(&set);
  timeout.tv_sec = 0;
  timeout.tv_usec = 100000;
  if (0==select(FD_SETSIZE, &set, NULL, NULL, &timeout)) printf("timeout\n");

  return 0;
}