c - What happens to initialization of static variable inside a function -


after stumbling onto this question , reading little more here (c++ issue works same in c/c++ afain) saw no mention realy happening inside function. 

void f(){   static int c = 0;   printf("%d\n",c++); }  int main(){   int  = 10;   while(i--)     f();   return 0; }

in snippet, c lifetime entire execution of program, line static int c = 0; has no meaning in next calls f() since c defined (static) variable, , assignment part obsolete (in next calls f()), since takes place @ first time.

so, compiler do? split f 2 functions - f_init, f_the_real_thing f_init initializes , f_the_real_thing prints, , calls 1 time f_init , onward, calls f_the_real_thing?

although standard not dictate how compilers must implement behavior, compilers less sophisticated thing: place c static memory segment, , tell loader place 0 c's address. way f comes straight pre-initialized c, , proceeds printing , incrementing if declaration line not there.

in c++ optionally adds code initialize c static initialization function, initializes static variables. in case, no call required.

in essence, amounts c starting lifetime before first call f. can think of c's behavior if static variable outside f() visibility constrained f()'s scope.


Comments

Post a Comment

Popular posts from this blog

python - Best design pattern for collection of objects -

i have following architecture: +-----------------+ | collection | | | | | | | | | +-----------------+ | ^ | | create() | | | | v | getitem(b) +------------+ | | item | | | | | | +------+ | | +------------+ a class managing collection of items, creates items. , these items may need other items collection. the actual code in python, , collection passes parameter created item . see it, bad practice. improvement can see pass few functions of collection needed item , instead of whole instance. for example: class collection: getitem(self, id): ... createitem(self, id): item = item(id, self) # <-- pass self ... class item: __init__(self, id, col): ... col.getite...
Read more

go - serving up pdfs using golang -

Image
just wondering if guys can code. it works serving images not pdf brochure. in advance func main(){ http.handlefunc("/", func(w http.responsewriter, r *http.request){ filename := "/var/www/filedipenser/brochure.pdf" streampdfbytes, err := ioutil.readfile( filename ) if err != nil { fmt.println(err) os.exit(1) } b := bytes.newbuffer(streampdfbytes) w.header().set("content-type", "application/pdf") if _, err := b.writeto(w); err != nil { fmt.fprintf(w, "%s", err) } w.write([]byte("pdf generated")) }) err := http.listenandserve(":4111", nil) if err != nil { log.fatal("listenandserve: ", err) fmt.println(err) } } the code bit inefficient appears working. however, pdf viewers might sensitive extraneous output adding end of http response stream...
Read more

how to add preprocess loader in webpack 2 -

i trying add preprocess loader in webpack 3. have installed successfully. not working here's webconfing file var debug = process.env.node_env !== "production"; var webpack = require('webpack'); var path = require('path'); module.exports = { context: path.join(__dirname, "src"), devtool: debug ? "inline-sourcemap" : null, entry: "./js/app.js", module: { loaders: [ { test: /\.jsx?$/, exclude: /(node_modules|bower_components)/, loader: 'babel-loader!preprocess-loader?+debug', // query: { // presets: ['react', 'es2015'], // plugins: ['react-html-attrs', 'transform-class-properties', 'transform-decorators-legacy'], // } }, { test: /\.css$/, loader: "style-loader!css-loader!sass-loader" } ] }, output: { path: __dirname + "/src/", f...
Read more