AW: Save and Load dynamic array. Delphi and D implement dynamic arrays at the languages core.

Made unique) before they are written to, but they keep pointed to the same - shared - memory area!Unlike Long Strings, that get 'split' when we change one of them (to get a unique copy), dynamic arrays keep pointed to the same area.A bit unexpected, perhaps, but at least we don't get delayed performance hits (like with Long Strings).Of course, since dynamic array contents are copied when we call SetLength, that's also all it takes (a call to SetLength) to create a unique copy of a dynamic array.Assigning to a dynamic-array index (for example, X := 'Answer') does not reallocate the array (we need to call SetLength to do that).Out-of-range indexes are not reported at compile time, but will raise an exception at run-time (with $R+ compiler directive).When dynamic-array variables are compared, their references are compared, not their array values.X = Y returns False but X = Y returns True.To truncate a dynamic array, pass it to the Copy function and assign the result back to the array variable.For example, if X is a dynamic array, X := Copy(X, 0, 2) truncates all but the first 2 elements of X.Once a dynamic array has been allocated, we can pass it to the standard functions Length, High, and Low.Length returns the number of elements in the array, High returns the array's highest possible index (Length - 1), and Low always returns 0.For a zero-length array, High indeed returns -1, so in that case High(X) < low(x).To instantiate the multi-dimensional array M (see declaration on top of this paper), we need to call SetLength with two integer arguments:Allocates an 10-by-5 array, and M denotes an element of that array.We can also create multidimensional dynamic arrays that are not rectangular.The first step is to call SetLength, passing it parameters for the first n dimensions of the array.Then, we can allocate the columns one at a time (giving them different lengths) for exampleMakes the third column of M 42 integers long.At this point (even if the other columns haven't been allocated) we can assign values to the third column for example, M := 7.This webpage © 2000-2015 by Bob Swart (aka Dr. Think of a Dynamic Array as a jumped up Integer (of course it is not - but it follows the same rules)In this article, I'll address a very handy language enhancement takes the ideas of Open Parameters and Long Strings back to the basics of arrays in the so-called Dynamic Arrays.In Delphi 4, in addition to declaring static arrays such asDynamic arrays specify type information (the number of dimensions and the type of the elements) but not the number of elements.X is a one-dimensional arrays of Strings, while M is a two dimensional array of Integers (like a Matrix).Dynamic arrays do not have a fixed size or length.Instead, memory for a dynamic array is (re-)allocated when we assign a value to the array or pass it to the SetLength procedure.Hence, the above declarations for X and M do not allocate memory.To create the array in memory, call SetLength.For example, given the declarations above,Allocates an array of 42 Strings, indexed 0 to 41.Dynamic arrays are always integer-indexed, always starting from 0.After calling SetLength, the previous content of the dynamic array - if any - is copied along (so data never gets lost if we constantly increase or decrease the length of the array).Using the above knowledge, we can write a small - and very inefficient, of course - program to read a number of lines from a textfile, and only allocate the exact number of strings that are needed.SetLength(X,Length(X)+1) // very inefficient.Dynamic-array variables are implicitly pointers and are managed by the same reference-counting technique used for Long Strings.To deallocate a dynamic array, assign nil to a variable that references the array or pass the variable to Finalize either of these methods disposes of the array, provided there are no other references to it.Warning: we should not apply the dereference operator (^) to a dynamic-array variable or pass it to the New or Dispose procedure.If X and Y are variables of the same dynamic-array type, X:=Y allocates X to the length of Y and points X to the same array as Y.Unlike strings, arrays are not automatically copied (i.e. Several cross-platform frameworks provide dynamic array implementations for C, including CFArray and Also, unless the dynamic array is a 'Global' variable, Delphi will destroy it automatically when it goes out of scope. Many scripting languages such as Perl and Ruby offer dynamic arrays as a built-in primitive data type. The only way to store/load such kind of data is IMO an additional field which stores/retrieves the. Here is the result of the built-in one of Delphi XE: Well, there are dynamic elements in your static array which also contain dynamic elements themselves.

Instead, memory for a dynamic array is reallocated when you assign a value to the array or pass it to the SetLength procedure. Dynamic arrays do not have a fixed size or length. This library has several functions that use arrays.

Dynamic arrays are always integer-indexed, always starting from 0.Dynamic-array variables are implicitly pointers and are managed by the same reference-counting technique used for long strings. For example, given the previous declaration,Allocates an array of 20 reals, indexed 0 to 19. To create the array in memory, call SetLength. The declaration does not allocate memory for MyFlexibleArray.

Do not apply the dereference operator (A) to a dynamic-array variable or pass it to the New or Dispose procedure.If X and y are variables of the same dynamic-array type, X := y points X to the same array as y. Dynamic arrays of length 0 have the value nil. Dynamic arrays are automatically released when their reference-count drops to zero.

For example,function CheckStrings(A: array of string): Boolean This indicates that the function operates on all arrays of the specified base type, regardless of their size, how they are indexed, or whether they are allocated statically or dynamically.

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