Array length: Difference between revisions

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@@ Line 581: / Line 581: @@
 </p>
 ====Solution with struct====
+<lang C>#define _CRT_SECURE_NO_WARNINGS    // turn off panic warnings
-<lang C>/*******************************************************************************
+#define _CRT_NONSTDC_NO_WARNINGS   // enable old-gold POSIX names in MSVS
-    A good (?) solution for the size of an array. A little more is needed for
-    polymorphic arrays - just use casting and void* instead int.
-    Obviously, this solution is written in (modern) C, but it would be better
-    to use C++ (classes, operators redefinitions, templates). Actually in C++
-    are out-of-box abstract data types (ADT) for this task (see also STL).
-*******************************************************************************/
+#include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <assert.h>
-struct IntegerArray
+struct StringArray
 {
-    size_t size;
+    size_t sizeOfArray;
-    int* elements;
+    size_t numberOfElements;
+    char** elements;
 };
+typedef struct StringArray* StringArray;
+StringArray StringArray_new(size_t size)
-typedef struct IntegerArray* IntegerArray;
-IntegerArray IntegerArray_new(size_t size)
 {
-    IntegerArray this = calloc(1, sizeof(struct IntegerArray));
+    StringArray this = calloc(1, sizeof(struct StringArray));
     if (this)
     {
         this->elements = calloc(size, sizeof(int));
         if (this->elements)
-            this->size = size;
+            this->sizeOfArray = size;
         else
         {
@@ Line 620: / Line 616: @@
 }
-IntegerArray_delete(IntegerArray* ptr_to_this)
+void StringArray_delete(StringArray* ptr_to_this)
 {
     assert(ptr_to_this != NULL);
-    IntegerArray this = (*ptr_to_this);
+    StringArray this = (*ptr_to_this);
     if (this)
     {
+        for (size_t i = 0; i < this->sizeOfArray; i++)
+            free(this->elements[i]);
         free(this->elements);
         free(this);
         this = NULL;
     }
+}
+void StringArray_add(StringArray this, ...)
+{
+    char* s;
+    va_list args;
+    va_start(args, this);
+    while (this->numberOfElements < this->sizeOfArray && (s = va_arg(args, char*)))
+        this->elements[this->numberOfElements++] = strdup(s);
+    va_end(args);
 }
@@ Line 635: / Line 643: @@
 int main(int argc, char* argv[])
 {
+    StringArray a = StringArray_new(10);
-    // An easy way to allocate an integer array.
+    StringArray_add(a, "apple", "orage", NULL);
-    //
-    IntegerArray a = IntegerArray_new(10);
-    assert(a != NULL);
+    printf(
+        "There are %d elements in an array with a capacity of %d elements:\n\n",
+        a->numberOfElements, a->sizeOfArray);
+    for (size_t i = 0; i < a->numberOfElements; i++)
-    // An example how to use this array.
+        printf("    the element %d is the string \"%s\"\n", i, a->elements[i]);
-    //
-    for (int i = 0; i < a->size; i++)
-        a->elements[i] = i * i; // an example expression
-    for (int i = 0; i < a->size; i++)
-        printf("element %d is %d\n", i, a->elements[i]);
-    printf("\nthe array size is %d\n", a->size);
+    StringArray_delete(&a);
-    // A safe way to delete array a.
-    //
-    IntegerArray_delete(&a);
     return EXIT_SUCCESS;
 }</lang>
 {{output}}
+<pre>There are 2 elements in an array with a capacity of 10 elements:
-<pre>element 0 is 0
-element 1 is 1
-element 2 is 4
-element 3 is 9
-element 4 is 16
-element 5 is 25
-element 6 is 36
-element 7 is 49
-element 8 is 64
-element 9 is 81
-the array size is 10
+    the element 0 is the string "apple"
+    the element 1 is the string "orage"</pre>
-</pre>
 ====An example why sizeof(A)/sizeof(E) may be a bad idea in C====