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POValues of an array changing randomly during execution
 

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  1. POValues of an array changing randomly during execution
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    <p>I'm trying to make a little programme in C using SDL, displaying a robot moving on a grid. This grid is represented by a txt file of 0s and 1s.</p> <p>Here is the fonction creating an array from the txt file, which works.</p> <pre><code>// create a map(array) from a text file int (*newMap())[SIZE_HEIGHT][SIZE_WIDTH] { static const char filename[] = "input.txt"; /* the name of a file to open */ FILE *file = fopen(filename, "r"); /* try to open the file */ int map[SIZE_HEIGHT][SIZE_WIDTH]; char line[BUFSIZ]; /* space to read a line into */ int k = 0; while ( fgets(line, sizeof line, file)!=NULL &amp;&amp; k&lt;SIZE_HEIGHT) /* read each line */ { int i; char *token = line; /* point to the beginning of the line */ for ( i = 0; i&lt;SIZE_WIDTH; i++ ) { map[k][i]=((int)*token)-48; token+=sizeof(char); printf("map[%d][%d]=%d\n", (int)k,(int)i,map[k][i]); } puts("----\n"); k++; } fclose(file); int (*p)[SIZE_HEIGHT][SIZE_WIDTH]; p=&amp;map; return p; </code></pre> <p>}</p> <p>Then I try to put the grid on the sreen (not the whole fonction):</p> <pre><code>#include &lt;stdlib.h&gt; #include &lt;stdio.h&gt; #include &lt;SDL/SDL.h&gt; #include &lt;time.h&gt; #include &lt;string.h&gt; #include "Parameters.h" #include "simulation.h" #include "editor.h" void simulate(SDL_Surface *ecran) { SDL_Surface *carreVert = SDL_LoadBMP("carreVert.bmp"); SDL_Surface *carreRouge = SDL_LoadBMP("carreRouge.bmp"); SDL_Surface *robot = SDL_LoadBMP("robotRouge.bmp"); SDL_SetColorKey(robot, SDL_SRCCOLORKEY, SDL_MapRGB(robot-&gt;format, 255, 255, 255)); int (*map)[SIZE_HEIGHT][SIZE_WIDTH]; map=newMap(); SDL_Rect positionFond; int i; int j; for(j=0; j&lt;SIZE_HEIGHT; j++) { for(i=0; i&lt;SIZE_WIDTH; i++) { positionFond.x = 100*i; positionFond.y = 100*j; if((*map)[j][i]+1) { SDL_BlitSurface(carreVert, NULL, ecran, &amp;positionFond); }else { SDL_BlitSurface(carreRouge, NULL, ecran, &amp;positionFond); } } } </code></pre> <p>And then something strange happens: when I observe the array *map with the debugger, I see that the values are changing when I go through the test. So the grid does appear, but not with the right pattern. Why does that happen?</p> <p>Edit:no error an compiler.</p> <p>Edit: Any guess of what might do that would be gladly accepted.</p>
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