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POrealloc from within a function
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  1. POrealloc from within a function
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    copied!<p>I have a struct called ball, a number of balls, an array of balls and a function where I want to add new balls to the array:</p> <p>The struct:</p> <pre><code>typedef struct ball{ BITMAP *image; int x; int y; int vector_x; int vector_y; } ball; </code></pre> <p>The (<em>non working</em> function):</p> <pre><code>void add_balls(int *num_balls, ball **myballs){ num_balls++; *myballs = realloc(*myballs, *num_balls * sizeof(ball)); *myballs[*num_balls-1]-&gt;x = rand() % 640; *myballs[*num_balls-1]-&gt;y = rand() % 480; *myballs[*num_balls-1]-&gt;vector_x = rand() % 10; *myballs[*num_balls-1]-&gt;vector_y = rand() % 10; *myballs[*num_balls-1]-&gt;image = load_bitmap("blue_ball.bmp", NULL); } </code></pre> <p>and the function call within main:</p> <pre><code>add_balls(&amp;num_balls, &amp;myballs); </code></pre> <p>The call to the function fails with the following error messages:</p> <pre><code>p.c: In function ‘add_balls’: p.c:19: error: invalid type argument of ‘unary *’ p.c:20: error: invalid type argument of ‘unary *’ p.c:21: error: invalid type argument of ‘unary *’ p.c:22: error: invalid type argument of ‘unary *’ p.c:23: error: incompatible types in assignment </code></pre> <p>Any help?</p> <p>That helped. It compiles now, but I get a segmentation fault error in runtime. Here is the complete code, if it interests:</p> <pre><code>#include &lt;allegro.h&gt; #include &lt;stdlib.h&gt; #include &lt;time.h&gt; #include &lt;math.h&gt; #define NUM_BALLS 10 typedef struct ball{ BITMAP *image; int x; int y; int vector_x; int vector_y; } ball; void add_balls(int *num_balls, ball **myballs){ num_balls++; myballs = realloc(*myballs, *num_balls * sizeof(ball)); myballs[*num_balls-1]-&gt;x = rand() % 640; myballs[*num_balls-1]-&gt;y = rand() % 480; myballs[*num_balls-1]-&gt;vector_x = rand() % 10; myballs[*num_balls-1]-&gt;vector_y = rand() % 10; myballs[*num_balls-1]-&gt;image = load_bitmap("blue_ball.bmp", NULL); } int main() { allegro_init(); install_keyboard(); srand(time(0)); install_timer(); set_color_depth(32); set_gfx_mode(GFX_AUTODETECT_WINDOWED, 640,480,0,0); BITMAP *buffer = NULL; buffer = create_bitmap(640,480); ball *myballs; myballs = malloc(NUM_BALLS * sizeof(ball)); int num_balls = NUM_BALLS; BITMAP *bg = NULL; bg = load_bitmap("bg.bmp",NULL); int i; for(i=0;i&lt;num_balls;i++){ myballs[i].x = rand() % 640; myballs[i].y = rand() % 480; myballs[i].vector_x = rand() % 10; myballs[i].vector_y = rand() % 10; myballs[i].image = load_bitmap("blue_ball.bmp", NULL); } int bg_vector_x; float bg_vector_y; while(!key[KEY_ESC]){ vsync(); for(i=0;i&lt;num_balls;i++){ if(myballs[i].x + myballs[i].vector_x &gt; 640 || myballs[i].x + myballs[i].vector_x &lt; 0){ myballs[i].vector_x *= -1; } if(myballs[i].y + myballs[i].vector_y &gt; 480 || myballs[i].y + myballs[i].vector_y &lt; 0){ myballs[i].vector_y *= -1; } myballs[i].x += myballs[i].vector_x; myballs[i].y += myballs[i].vector_y; } if(key[KEY_UP]){ add_balls(&amp;num_balls, &amp;myballs); } clear_bitmap(buffer); int ii; for(i=0;i&lt;3;i++){ for(ii=-1;ii&lt;3;ii++){ draw_sprite(buffer, bg ,(bg_vector_x%528)+(i*528),100*cos(bg_vector_y) + ii*353); } } bg_vector_x++; bg_vector_y+=0.1; for(i=0;i&lt;num_balls;i++){ draw_sprite(buffer, myballs[i].image, myballs[i].x,myballs[i].y); } blit(buffer, screen, 0,0,0,0,640,480); } for(i=0;i&lt;num_balls;i++){ destroy_bitmap(myballs[i].image); } free(myballs); destroy_bitmap(buffer); } END_OF_MAIN() </code></pre>
 

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