131 lines
2.2 KiB
D
131 lines
2.2 KiB
D
import std.stdio: writeln;
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void pointers() {
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int myVariable = 120;
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int* myPointer = &myVariable;
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/*
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Valid pointer declarations:
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type* name;
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type * name;
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type *name;
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*/
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writeln("Memory address of myVariable:\t", &myVariable);
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writeln("Value of myPointer:\t\t", myPointer);
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writeln("\nValue of myVariable: ", myVariable);
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writeln("Value of myVariable accessed through my Pointer: ", *myPointer);
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*myPointer += 5; // modifies the value of myVariable
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// myPointer += 5; // !!! modifies the address myPointer points at by sizeof(int)*5
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writeln("\n| *myPointer += 5 |\t => myVariable: ", myVariable);
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myPointer = null;
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/*
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// increments the value of a copy
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void increment(int num) {
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num += 1;
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}
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// increments the actual value of the variable
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void increment(ref int num) {
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num += 1;
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}
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// increments the actual value of the variable
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void increment(int* num) {
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*num += 1;
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// num += 1; // modifying the address
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}
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*/
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}
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void gc_allocations() /* @nogc */{
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import core.memory: GC;
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/**** GC basics ****/
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// disabling GC collection cycles | it does not gurantee, that GC cycles won't be run
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// GC cycle will be run anyway, if more memory is required
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GC.disable();
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// enabling GC collection cycles
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GC.enable();
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// explicitly starting a GC collection cycle
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GC.collect();
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int* var1 = new int; // allocating an int on GC heap
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int[] var2 = new int[42]; // allocating a dynamic array of 42 ints on GC heap
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var2 ~= 2;
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// allocating a fixed size array on the GC heap
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//int* var3 = cast(int*)GC.malloc(int.sizeof * 42);
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//int* var3 = cast(int*)GC.realloc(null, int.sizeof * 42);
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int* var3 = cast(int*)GC.calloc(int.sizeof * 42);
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GC.free(var3);
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}
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void stdc_allocations() {
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import core.stdc.stdlib: malloc, free; // malloc, realloc, etc... from C stdlib
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import core.memory: GC;
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int size = 42;
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// allocating memory the C-way
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int* var = cast(int*)malloc(int.sizeof * size);
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// (*) optional: adding var to GC memory
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GC.addRange(var, size);
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// ...........
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// if (*), then var should be removed before freeing
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GC.removeRange(var);
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// freeing var
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free(var);
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}
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void main() {
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pointers();
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gc_allocations();
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stdc_allocations();
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}
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