php - Referencing the same variable across two different classes -

- 

<?php  class foo{     public $basket;      public function __construct()     {         $this->basket = 1;     }      public function getbasket(){         return $this->basket;     } }  class bar{     public function __construct(&$basket)     {         $basket++;     } }  $newfoo = new foo(); $newbar = new bar($newfoo->getbasket());  echo $newfoo->getbasket();  ?>

i hoping initialise $basket value in 1 class , manipulate same variable via class. unfortunately, keep getting "notice: variables should passed reference in " error message.

question: how can change code make happen? thank you.

change

$newbar = new bar($newfoo->getbasket());

to

$basket = $newfoo->getbasket(); $newbar = new bar($basket);

the first way doesn't work because php doesn't have variable hold value you're passing new bar() consequence, nothing can passed reference.

the second way works because $basket var fixed reference in memory, can passed reference new bar()

you asked in comments:

have changed code yours. echo $newfoo->getbasket(); produces 1 (i hoping 2).

1 produced because each call getbasket() gives fresh copy of class variable. $basket passed new bar() equals 2, that's not you're echoing.

if want result of getbasket() , variable $basket refer same reference in memory, need make 2 changes:

1 change function declaration to:

public function &getbasket()

2 change how store function result to:

$basket = &$newfoo->getbasket();

now echo return 2 because have unique basket reference throughout code

see docs


Comments

Post a Comment

Popular posts from this blog

Spring Boot + JPA + Hibernate: Unable to locate persister -

-
i trying work entity inside request method of spring boot application. entity in project , pom.xml has dependencies it. why error message?: org.hibernate.unknownentitytypeexception: unable locate persister: com.ric.bill.model.bs.par package com.ric.web; import java.util.concurrent.atomic.atomiclong; import javax.persistence.entitymanager; import javax.persistence.persistencecontext; import net.sf.ehcache.cachemanager; import net.sf.ehcache.management.cache; import net.sf.ehcache.management.cachestatistics; import org.hibernate.stat.statistics; import org.springframework.beans.factory.annotation.autowired; import org.springframework.boot.autoconfigure.domain.entityscan; import org.springframework.cache.annotation.enablecaching; import org.springframework.transaction.annotation.enabletransactionmanagement; import org.springframework.transaction.annotation.propagation; import org.springframework.transaction.annotation.transactional; import org.springframework.web.bind.annotati...
Read more

go - Golang: panic: runtime error: invalid memory address or nil pointer dereference using bufio.Scanner -

-
i implementing go program uses bufio.scanner , bufio.writer have packaged code follows package main import ( "fmt" "player/command" "strings" ) func main() { //enter code here. read input stdin. print output stdout commands.scanner.scan() { //scan new line , send comand variable check command exist or not input := strings.split(strings.trim(commands.scanner.text(), " "), " ") command := input[0] if command == "" { fmt.printf("$ %s:", commands.pwd) continue } if !commands.commands[command] { commands.throwerror("cannot recognize input.") } else { commands.execute(command, input[1:], nil) } fmt.printf("$ %s:", commands.pwd) } } i using init.go file in main package follows package main import ( "flag" "player/sourc...
Read more

c - double free or corruption (fasttop) -

-
this code reads null terminated string file (file containing null terminated strings & should provide index wanted string). error: *** error in `./main': double free or corruption (fasttop): 0x090a4a80 *** aborted code: char *tmp_realloc=null; char *sstring=null; int i=1; /*set file pointer point string*/ fseek(fh,index,seek_set); sstring=(char*)malloc(sizeof(char)); if(sstring == null) return null; tmp_realloc=sstring; while( (*(sstring+i-1)=(char)fgetc((file*)fh)) != 0x0 ) { /*reallocate more memory*/ tmp_realloc=(char*)realloc((char*)sstring,++i); /*if not same address copy old new & set old point new*/ if(tmp_realloc != sstring){ strcpy((char*)tmp_realloc,(char*)sstring); free(sstring); sstring=tmp_realloc; } } could tell me pointer causing issue (& reason) ? remove part /*if not same address copy old new & set old point new*/ if(tmp_realloc != sstring){ strc...
Read more