Callback Timer function in C++ -


i trying implement callback timer function in c++ should callback after timeout. listening on socket , waiting messages on it. if have getmessages() , want pass timer function in argument. how can implemented after receive of message, timer started , callback happens if there timeout before next messages arrives.

i new callback functions. appreciated. thanks!

you know, there no such things callback functions in c++. there are, however, function pointers.

function pointers literally - pointers functions. "normal" pointers specify data type pointer points (e.g. int *foo, char *bar...); function pointers work in specify signature of function: void (*baz)(int). notice baz name of pointer in case.

without code i'm not sure how timing system work. first thing come mind tick function called repeatedly. can either call function @ regular intervals or measure time between function calls - in either case know time has elapsed. increment (or decrement) allotted time variable, , when time use function pointer trigger "callback".

one thing may find useful typedefing callback function so: typedef void (*callback)(int) (again, callback identifier). can define function other member (callback func = foo) , call (func(12)).

ps: there resources function pointers dotted around se. here's one.


Comments

Post a Comment

Popular posts from this blog

javascript - Jquery show_hide, what to add in order to make the page scroll to the bottom of the hidden field once button is clicked -

i have button on website when clicked, reveals map. button can seen when page first loads up, when clicked, section holding map slides open , goes out of screen since page loads @ top (normal). want page scroll down bottom of div select when button pushed, if map out of screen. if page scrolled down, , clicks show map button, don't want page jump bottom of map. i tried figure out myself, no luck. seasoned jquery coders able give me guidance? many thanks! map = mapdiv.gmap3("get"); infobox = new infobox({ pixeloffset: new google.maps.size(-220, -310), closeboxurl: '', enableeventpropagation: true }); mapdiv.delegate('.infobox .close','click',function () { infobox.close(); }); jquery(".slidingdiv").hide(); jquery(".show_hide").show(); jquery('.show_hide').click(function(){ lastcenter=map.getcenter(); jquery(".slidingdiv...
Read more

python - Django-cities exits with "killed" -

i trying install django-cities on server 500mb ram. whenever run: manage.py cities the system exits saying killed. trying run: manage.py cities --import=country --force worked, guessing matter of running out of memory. to bypass, tried refer package local copy of cities' data file. still didn't work. any ideas on how can migrate data without having increase memory on server? based on suggestion comments, solved setting temporary swap file. if unfamiliar it, can follow these steps: set swap file touch /var/swap.img chmod 600 /var/swap.img set swap file size cd /var dd if=/dev/zero of=/var/swap.img bs=1024k count=1000 this create 1gb swap file. prepare disk image mkswap /var/swap.img activate swap memory swapon /var/swap.img once done, can turn off swap image: swapoff /var/swap.img more information on virtual memory , swap files can found here: https://www.digitalocean.com/community/tutorials/how-to-configure-virtual-me...
Read more

python - How to get a widget position inside it's layout in Kivy? -

i have gridlayout , added image widgets on after adding of images want draw rectangle in each image using canvas couldn't because don't know exact image widgets positions on gridlayout. code: http://paste.ofcode.org/3bdp9yhjrcrzmsztbu9hqp4 http://paste.ofcode.org/3az3gx4fxzr9dlhe2ami97c in last line of python code : rectangle(pos = (child.x - 2.4, child.y + 467), size = (70, 70)) how draw rectangle in child(my method not good^), also why gridlayout not coming in center after setting it's pos_hint = {"center_x" : .5}? if understand question right, try use such methods to_local() , to_parent() , to_widget() , to_window() . try substract position of gridlayout widgets' positions.
Read more