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POGeneric stack in plain C does not copies structures correct
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  1. POGeneric stack in plain C does not copies structures correct
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    copied!<p>So I have implemented a generic stack in Plain C. It should copy different type of data, inclusive structures. And by structures I have the problem.</p> <p>So here's the structure of the stack:</p> <pre><code>/* * Definite genStack as a structure. * Pointer elems points to the objects lying on the stack * The variable elemSize spiecifies the size of an element * The variable logLength specifies the number of actually * lying on the stack objects * The variable allocLenght specifies the allocated size */ typedef struct{ void* elems; int elemSize; int logLength; int allocLength; }genStack; </code></pre> <p>Push and pop functions:</p> <pre><code>void GenStackPush(genStack *s, const void *elemAddr) { /* if stack is full - allocates more memory */ if (GenStackFull(s)) { GenStackAlloc(s, s-&gt;elemSize); } memcpy((char*) (s-&gt;elems)+(s-&gt;logLength), elemAddr, sizeof(*elemAddr)); s-&gt;logLength++; } void GenStackPop(genStack *s, void *elemAddr) { if(GenStackEmpty(s)) { fprintf(stderr, "Can't pop element from stack: stack is empty.\n"); } else { s-&gt;logLength--; memcpy((void*) elemAddr, (s-&gt;elems)+(s-&gt;logLength), sizeof(s-&gt;elems[s-&gt;logLength])); } } </code></pre> <p>Simple structures test:</p> <p>gentest.h:</p> <pre><code>#ifndef GENTEST1_H #define GENTEST1_H typedef struct { char* name; int age; char gender; }person; #endif </code></pre> <p>gentest.c:</p> <pre><code>#include &lt;stdio.h&gt; #include &lt;stdlib.h&gt; #include "gentest1.h" #include "genstacklib.h" int main(int argc, char* argv[]) { genStack StructStack; person testPerson[5]; person* newPerson; person* test; int i; newPerson = (void*) malloc (sizeof(person)); testPerson[0].name = "Alex"; testPerson[0].age = 21; testPerson[0].gender = 'm'; testPerson[1].name = "Vanja"; testPerson[1].age = 20; testPerson[1].gender = 'm'; testPerson[2].name = "sjrgsde"; testPerson[2].age = 11; testPerson[2].gender = 'w'; testPerson[3].name = "wergsggsd"; testPerson[3].age = 99; testPerson[3].gender = 'y'; testPerson[4].name = "adaasxx"; testPerson[4].age = 13; testPerson[4].gender = 'g'; GenStackNew(&amp;StructStack, sizeof(person)); printf("sizeof(person) = %lu\n", sizeof(person)); for (i = 0; i &lt; 5; i++) { newPerson = &amp;testPerson[i]; GenStackPush(&amp;StructStack, newPerson); printf("Pushed: %s, %d, %c\n", newPerson-&gt;name, newPerson-&gt;age, newPerson-&gt;gender); } test = (void*) malloc (sizeof(person)); test-&gt;name = "test"; test-&gt;age = 0; test-&gt;gender = 't'; while(!GenStackEmpty(&amp;StructStack)) { GenStackPop(&amp;StructStack, test); printf("Popped: %s, %d, %c\n", test-&gt;name, test-&gt;age, test-&gt;gender); } GenStackDispose(&amp;StructStack); return 0; } </code></pre> <p>And here's the output I get:</p> <pre><code>./gentest1 elemSize = 16 GenStackInitialAlocationSize = 4 sizeof(person) = 16 Pushed: Alex, 21, m Pushed: Vanja, 20, m Pushed: sjrgsde, 11, w Pushed: wergsggsd, 99, y New size of alloc = 8 Pushed: adaasxx, 13, g Popped: adaasxx, 0, t Popped: wergsggsd, 0, t Popped: sjrgsde, 0, t Popped: Vanja, 0, t Popped: Alex, 0, t </code></pre> <p>As you can see, I can receive names, but no age or gender. I've tried a lot of options, but still getting Segmentation Fault or the output from above. For moment, the output above is the finest output I get, but still not what I want. </p> <p>The question is - how can I get the output I need? Thanks in advance.</p> <p>To avoid some questions: sizeof(person) = s->elemSize</p> <p>It is defined by creating the stack:</p> <p>genstacklib.c:</p> <pre><code>void GenStackNew(genStack *s, int elemSize) { void* newElems; /* Allocate a new array to hold the contents. */ newElems = (void*) malloc(elemSize * GenStackInitialAlocationSize); printf("elemSize = %d\tGenStackInitialAlocationSize = %d\n", elemSize, GenStackInitialAlocationSize); if (newElems == NULL) { fprintf(stderr, "Error with allocating the stack.\n"); exit(1); /* Exit, returning error code. */ } s-&gt;elems = newElems; s-&gt;elemSize = elemSize; s-&gt;allocLength = GenStackInitialAlocationSize; s-&gt;logLength = 0; /*is empty*/ } </code></pre> <p>gentest.c:</p> <pre><code>GenStackNew(&amp;StructStack, sizeof(person)); printf("sizeof(person) = %lu\n", sizeof(person)); </code></pre>
 

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