If you are familiar with pointers, that’s an analogy you can take. You’re actually passing a pointer, so obj.someProperty would dereference to that property and actually override that, while merely overriding obj would kill off the pointer and not overwrite the object.
As Rytmis said, Java passes references by value. What this means is that you can legitimately call mutating methods on the parameters of a method, but you cannot reassign them and expect the value to propagate. Example: private void goodChangeDog(Dog dog) { dog.setColor(Color.BLACK); // works as expected! } private void badChangeDog(Dog dog) { dog = … Read more
Use the inout qualifier for a function parameter. func swapTwoInts(a: inout Int, b: inout Int) { let temporaryA = a a = b b = temporaryA } swapTwoInts(&someInt, &anotherInt) See Function Parameters and Return Values in the docs.
It’s 2018, and this question deserves an update. At least in Bash, as of Bash 4.3-alpha, you can use namerefs to pass function arguments by reference: function boo() { local -n ref=$1 ref=”new” } SOME_VAR=’old’ echo $SOME_VAR # -> old boo SOME_VAR echo $SOME_VAR # -> new The critical pieces here are: Passing the variable’s … Read more
A var parameter will be passed by reference, and that’s it. An out parameter is also passed by reference, but it’s assumed that the input value is irrelevant. For managed types, (strings, Interfaces, etc,) the compiler will enforce this, by clearing the variable before the routine begins, equivalent to writing param := nil. For unmanaged … Read more
you cannot pass by reference in C but can use pointers as an alternative Yup, thats correct. To elaborate a little more. Whatever you pass as an argument to c functions, it is passed by values only. Whether it be a variable’s value or the variable address. What makes the difference is what you are … Read more
No. Objects in assignment statements are immutable. R will copy the object not just the reference. > v = matrix(1:12, nrow=4) > v [,1] [,2] [,3] [1,] 1 5 9 [2,] 2 6 10 [3,] 3 7 11 [4,] 4 8 12 > v1 = v > v1[,1] # fetch the first column [1] 1 … Read more
In a test with 100 000 iterations of calling a function with a string of 20 kB, the results are: Function that just reads / uses the parameter pass by value: 0.12065005 seconds pass by reference: 1.52171397 seconds Function to write / change the parameter pass by value: 1.52223396 seconds pass by reference: 1.52388787 seconds … Read more
In C arrays are passed as a pointer to the first element. They are the only element that is not really passed by value (the pointer is passed by value, but the array is not copied). That allows the called function to modify the contents. void reset( int *array, int size) { memset(array,0,size * sizeof(*array)); … Read more