pass-by-reference

问题 This question already has answers here : Is Java “pass-by-reference” or “pass-by-value”? (86 answers) Closed 4 years ago . I am creating ArrayList l1 and passing l1 reference to the method foo. As we know that Java doesn't support Pass-By-Reference but here its giving different results. See the below code public static void main(String[] args) { List l1 = new ArrayList(Arrays.asList(4,6,7,8)); System.out.println("Printing list before method calling:"+ l1); foo(l1); System.out.println(

问题 I have a simple function intReference int intReference(int *intArray) Where I am passing intArray by reference. How do I set the interface file for SWIG such that it can do that? Thanks, 回答1: This is the pattern I think you want: intReference.i %module intReference %{ extern int intReference(int intArray[]); %} %typemap(jtype) int intArray[] "int[]" %typemap(jstype) int intArray[] "int[]" %typemap(javain) int intArray[] "$javainput" %typemap(jni) int intArray[] "jintArray" %typemap(in) int

问题 I think of DataGridView's as being memory hogs. Is it better to pass by value a datagridview or by reference? Should it even be passed at all? 回答1: Passing it by value or reference isn't going to matter from a memory stand point, because the DataGridView is a reference type, not a value type. 回答2: The type DataGridView is a reference type and hence it's not possible to pass the object by value. You can pass the reference to the object by value but that is a very small (typically pointer sized

问题 I am newbie in java/android. I am a c/c++ developer. May i know how to pass a reference as parameter in android. An illustrative c sample code shown below void main() { int no1 = 3, no2 = 2, sum = 0; findsum( no1, no2, sum ); printf("sum=%d", sum ); } void findsum( int no1, int no2, int& sum ) { sum = no1 + no2; } please suggest me a solution thanks 回答1: You cannot pass an int as reference in Java . int is a primary type, it can be passed only by value. If you still need to pass an int

问题 Should I pass std::string by value or by reference to one function. This function store this values in member variable of class. I am always confuse when about pass by value or reference. Please clear my confusion about this. Here is code : class DataStore { public: void addFile(const string& filename, const set< std::string>& filePaths) { if (dataStoreMap.insert(make_pair(filename, filePaths)).second) { cout << "Data Added" <<endl; } else { cout << "Data not Added" << endl; } } private: //

问题 I used to think Java supports both pass by value and passby reference but i came accross many discussions like Java is always pass by value, with no exceptions, ever . Java is always pass-by-value Java always passes arguments by value NOT by reference. Java passes references by value.So you can't change the reference that gets passed in. If java only supports pass by value how does java.util.Array.sort() or Collections.sort(unsortList) work? int iArr[] = {2, 1, 9, 6, 4};// sorting array

问题 I want to remove elements from a few large arrays with a subroutine. I use a reference to avoid a copy into the sub. @a=qw(ok now what is hi the matter); sub zonk { $array=shift; # this is a reference of an array foreach $i (0..$#$array) { # I saw some say to avoid last element to get size #if (@$array[$i] =~ /hi/) { delete @$array[$i]; } #if ($array->[$i] =~ /hi/) { delete $array->[$i]; } #if ($array->[$i] =~ /hi/) { delete @$array->[$i]; } if ($array->[$i] =~ /hi/) { print "FOUND "; } print

问题 This question sounds to be partially answered here but this is not enough specific to me. I would like to understand better when an object is updated by reference and when it is copied. The simpler example is vector growing. The following code is blazingly inefficient in R because the memory is not allocated before the loop and a copy is made at each iteration. x = runif(10) y = c() for(i in 2:length(x)) y = c(y, x[i] - x[i-1]) Allocating the memory enable to reserve some memory without

问题 I have this code in a library: class Parent { //some data and functions }; void myfunc(Parent& ref); and I want to do this code in my application: class Child : public Parent { // some other data and functions void dostuff() { myfunc(*this); } }; Is it safe to pass *this? (no slicing, no copying, ...) Is it better to call myfunc like this: myfunc( * ((Parent*)this) ) Note that I don't have control on what happens inside myfunc, in some cases I don't even know what happens inside there. I used

问题 Can we swap two numbers in Java using pass by reference or call by reference? Recently when I came across swapping two numbers in Java I wrote class Swap{ int a,b; void getNos(){ System.out.println("input nos"); a = scan.nextInt(); b = scan.nextInt(); // where scan is object of scanner class } void swap(){ int temp; temp = this.a; this.a = thisb; this.b = this.a; } } In the main method I call the above mentioned methods and take two integers a , b and then using the second method I swap the