c++ - How do I understand about cpp headfiles -


  • why headfiles of main.cpp need include .h headfiles contain declaration instead of implementation?

  • can write class in cpp file including both declaration , implementation , include cpp file main.cpp headfile?

  • how can include headfile not in project?

technically, header file (or other file decide #include) can contains absolutely whole makes complete c++ program.

what happens when compiler (technically, part of compiler package called "c preprocessor") sees #include "somefile.h" in source-code takes file, , "pastes" main file being compiled. "pretend" preprocessor opening headerfile, marking , pasting main file.

the point header files avoid copying , pasting same bit of c++ several source files. example, declaration of class can put header file myclass.h, actual implementation myclass.cpp file, , part of program using myclass need include header.

header files not part of project typically surrounded angle brackets, #include <header.h> include "header.h" other project.


Comments

Post a Comment

Popular posts from this blog

linux - Does gcc have any options to add version info in ELF binary file? -

i mean whether gcc can insert source code version infor elf binary section or similar. not want change source file, add info gcc option in makefile. you can emit version info text file, turn text file object file statically link executable. the first step simple have write code: script or write version info in format plain text file. write makefile rule produce version.o version.txt, using objcopy . you'll have object file 2 useful symbols defined in it: beginning , end of textual version info. add generated object executable, , you'll able access version 2 ways: running strings on binary, or writing code in application print version string (you'll need declare start , end symbols variables in header file).
Read more

android - send complex objects as post php java -

is possible send contact numbers via post php class inside eclipse ? or post limited primitive types , have find work arounds send them string ? i propose: send them json in post request, befor start, have @ gson project , keep in mind set content application -> json. luck
Read more

charts - What graph/dashboard product is facebook using in Dashboard: PUE & WUE -

i love facebook dashboard: pue & wue. beautifull can point out if there open source or commercial product offer similar style? here link https://www.facebook.com/forestcitydatacenter?sk=app_288655784601722&app_data so read through 29,888 lines of javascript ya.. biggest js file i've ever seen. looks make graph using variety of tools, including tween.js . it'd fascinating chat whoever made it. code wheel graph object starts @ line 27,266 text var graphcomponent = class.extend({ . can find source @ https://www.fbpuewue.com/assets/application-3a3af20f7fa3591229c79442ae3d1c26.js . sorry if dissapoints it's not awesome plugin can use :/ share pain. let me know if have questions :)
Read more