using sizeof () to find function type length in ANSI C -

-

this question has answer here:

when need find function type length, used sizeof () it.

the expected result 4 bytes , 8 bytes, now, result 1 byte through gcc.

why output 1 byte, not 4 bytes , 8 bytes?

#include <stdio.h>  int foo ();  double bar ();   int  main (void) {     printf ("int foo () %lu\n", sizeof (foo));       printf ("double bar () %lu\n", sizeof (bar)); }  double  bar (void) {     return 1.1; }  int foo (void) {     return 0; }

although standard says "the sizeof operator shall not applied expression has function type" (§6.5.3.4/1), in gnu c, result of doing defined:

"sizeof allowed on void , on function types, , returns 1"
~ gcc, 6.23 arithmetic on void- , function-pointers

also have at: why size of function in c 1 byte?


Comments

Post a Comment

Popular posts from this blog

c# - How Configure Devart dotConnect for SQLite Code First? -

-
can configure following sample code ? when run following code, error : no entity framework provider found ado.net provider invariant name 'devart.data.sqlite' setting in machine.config <system.data> <dbproviderfactories> <add name="dotconnect sqlite" invariant="devart.data.sqlite" description="devart dotconnect sqlite" type="devart.data.sqlite.sqliteproviderfactory, devart.data.sqlite, version=4.6.287.0, culture=neutral, publickeytoken=09af7300eec23701" /> </dbproviderfactories> </system.data> after add below block code in app.config <?xml version="1.0"?> <configuration>   <configsections> <!-- more information on entity framework configuration, visit http://go.microsoft.com/fwlink/?linkid=237468 --> <section name="entityframework" type="system.data.entity.internal.configfile.entityframeworksection, entit...
Read more

java - Copying object fields -

-
what best way of copying classes when need have 2 independent variables? have simple class: public class myclass { boolean = false; string b= "not empty"; } do need make method : assign(myclass data ) { a= data.a; b= data.b; } is there automatic method copy (duplicate) objects in java? do need make method : pretty close. instead of making method, should make constructor. such constructors called copy constructor , , create them this: myclass(myclass data) { = data.a; b = data.b; } and create copy of instance, use constructor this: myclass obj1 = new myclass(); myclass obj2 = new myclass(obj1); copy constructor can tedious : using copy constructor create deep-copy can tedious, when class has mutable fields. in case, assignment create copy of reference, , not object itself. have create copy of fields (if want deep copy). can go recursive. a better way create deep copy serialize , deserialize object. why not use clone()? ...
Read more

c++ - Clear the memory after returning a vector in a function -

-
i have function processes , stores lot of data in , returns results vector of class. amount of data stored in function tremendous , want clear storage memory of function after finished job. necessary (does function automatically clear memory) or should clear memory function? update: vector<customers> process(char* const *filename, vector<int> id) { vector<customers> list_of_customers; (perform actions) return list_of_customers; } variables defined locally within function automatically released @ end of function scope. destructors objects called, should free memory allocated objects (if objects coded correctly). example of such object std::vector . anything you've allocated new must have corresponding delete release storage. try avoid doing own allocation , use raii instead, i.e. containers or smart pointers.
Read more