pass-by-reference

What's going on in the background with regard to this JavaScript?

I was reviewing some today, when I encountered the following convention : TestParam(1); function TestParam(p){ var p = p + 1; alert(p); // alerts '2' } Now, obviously, the developer didn't mean to delcare 'p' within the function, instead maybe meaning: p = p + 1; But the code still worked, i.e. the value alerted was...

pass by reference without the ref keyword

I'm not a veteran in socket programming, so while analyzing code I found in a database API I came across this code public static void WriteInt(int i, NetworkStream bufOutputStream) { byte[] buffer = new byte[IntSize]; WriteInt(i, buffer, 0); bufOutputStream.Write(buffer, 0, buffer.Length); } pu...

Whats the best way to send QStrings in a function call?

I would like to know what is the most efficient and practical way of sending a Qstring as a parameter to a function, in QT more specifically. I want to use a reference. The problem is I also want to instantiate that string in the function itself like so for example: this is the function prototype: void myFunction(QString & theMsg); th...

Pass by reference more expensive than pass by value

Hello everyone, this question has been bugging me for a while, so i thought i'd ask. Is there a case where pass-by-reference is more expensive than pass-by-value in C++? If so, what would that case be? Thanks. ...

Pass by reference 2D dynamically allocated double array in C

Hi, I'm trying to convert my string into a dynamic array of doubles. Each space of my string represents a column, each ";" represents a new row. When this code runs, it only works for when *F[0][col]. When it gets to *F[1][col] it gives me the error "Unhandled exception at 0x00e4483c in CCode.exe: 0xC0000005: Access violation reading l...

How to pass objects to functions in C++?

I am new to C++ programming, but I have experience in Java. I need guidance on how to pass objects to functions in C++. Do I need to pass pointers, references, or non-pointer and non-reference values? I remember in Java there are no such issues since we pass just the variable that holds reference to the objects. It would be great if yo...

When to pass-by-reference in PHP

Im wondering if its good practice to pass-by-reference when you are only reading a variable, or if it should always be passed as a value. Example with pass-by-reference: $a = 'fish and chips'; $b = do_my_hash($a); echo $b; function &do_my_hash(&$value){ return md5($value); } Example with pass-by-value: $a = 'fish and chips'; $b ...

How to pass value by reference in C#?

I have the following linq code. searchResults = (from item1 in searchResults join item2 in coll on item1.skuID equals item2.Skuid where item2.SearchableValue == value select item1).ToList(); The variable searchResults is passed in the method as a generic List. The linq segment ab...

What is useful about a reference-to-array parameter?

I recently found some code like this: typedef int TenInts[10]; void foo(TenInts &arr); What can you do in the body of foo() that is useful, that you could not do if the declaration was: void foo(int *arr); // or, void foo(int arr[]); // or, void foo(int arr[10]); // ? I found a question that asks how to pass a reference to an ...

To get reference counting, do I have to clutter my APIs with shared_ptr?

I recently had the following memory bug, which is easy to spot here, but can be harder to detect in more complex code: class Foo : public IFoo { const Bar& bar_; public: Foo(const Bar& bar) : bar_(bar) { } void test() { // access bar_ here } }; int baz() { IFoo* foo = NULL; if(whatever) { Bar bar; foo = new Fo...

How to Increment a class Integer references value in java from another method.

package myintergertest; /** * * @author Engineering */ public class Main { /** * @param args the command line arguments */ public static void main(String[] args) { //this one does not increment Integer n = new Integer(0); System.out.println("n=" + n); Increment(n); System.ou...

Passing primitive types as out param in Java

I need to return/update a boolean while returning a list of stuff from a method. Java can't return tuples and I didn’t want to make a separate class for this, so figured I would pass the bool as an out param. That’s what our C++ client does, passes bool by reference. That would work for a normal class since java sort of has pass-by-re...

Passing by reference in C

If C does not support passing a variable by reference, why does this work? #include <stdio.h> void f(int *j) { (*j)++; } int main() { int i = 20; int *p = &i; f(p); printf("i = %d\n", i); return 0; } Output $ gcc -std=c99 test.c $ a.exe i = 21 ...

PHP 5 messing up pass by reference

I am creating this UnitOfWork object and an Db adapter that uses it. When the Adapter fetches a row: it will turn the row into an object of the correct type put the object into the UnitOfWork to be updated return the object Example code $entity = $adapter->findById(1); The internal working dummy: class Adapter { function find...

Question on Call-By-Reference ?

main() calls Call_By_Test() function with argument parameter First Node. I have freed the First Node in Call_By_Test() but First node address not freed in main(), why ?. typedef struct LinkList{ int data; struct LinkList *next; }mynode; void Call_By_Test(mynode * first) { free(first->next); first->next = (mynode *)NULL;...

pass by reference c++

My teacher in c++ told me that call by reference should only be used if I'm not going to change anything on the arrays inside the function. I have some really big vectors that I'm passing around in my program. All the vectors will be modified inside the functions. My matrices are of sizes about [256*256][256][50]... Is there some partic...

Please clarify my understanding regarding object and reference and value type is current?

Please clarify my understanding regarding object and reference and value type is current? Object means a memory location in RAM where we allocate memory while executing a program Reference means a location(address) in the memory. Passing by reference means - we are passing or pointing a memory location to the function to take the valu...

C++ functions taking values, where they should be taking references

I'm just learning c++, and coming from c, some function calls I'm seeing in the book confuse me: char a; cin.get(a); In C, this couldn't possibly work, if you did that, there would be no way to get the output, because you are passing by value, and not by reference, why does this work in c++? Is referencing and dereferncing made implic...

Are ILists passed by value?

Passing Value Type parameters to functions in c# is by value unless you use the ref or out keyword on the parameter. But does this also apply to Reference Types? Specifically I have a function that takes an IList<Foo>. Will the list passed to my function be a copy of the list with copy of its contained objects? Or will modifications to...

Class with pass-by-reference object gives compile error

I've got a class A defined in a separate header file. I want class B to have a reference to a object of class A stored as a variable. Like this: File: A.h class A { //Header for class A... }; File: B.h #include "A.h" class B { private: (24) A &variableName; public: (36) B(A &varName); }; When i try to co...