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POUnable to allocate pointers in C
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  1. POUnable to allocate pointers in C
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    copied!<p>I am making a graph using <strong>Adjacency Matrix</strong>.<br /><br /> This is my header file - <strong>graph.h</strong> - <br /></p> <pre><code>typedef struct Node{ int vertex; }Node_t; typedef Node_t *Row; typedef struct graph_t{ int noOfVertices; Row *rowPointer; }graph_t, *graph_p; </code></pre> <p>This is my definition file - <strong>graph.c</strong> - <br /></p> <pre><code>graph_p createGraph(int noOfVertices){ int i, j; graph_p graph = (graph_p)malloc(sizeof(graph_t)); graph-&gt;noOfVertices = noOfVertices; graph-&gt;rowPointer = (Row *)malloc(noOfVertices * sizeof(Row)); fprintf(stdout, "\nValue of graph-&gt;rowPointer: %p\n", graph-&gt;rowPointer); for(i = 0; i &lt; noOfVertices; i++){ Row r = (Node_t *)malloc(noOfVertices * sizeof(Node_t)); fprintf(stdout, "Value of r: %p\n", r); graph-&gt;rowPointer[i] = &amp;r; fprintf(stdout, "Value of graph-&gt;rowPointer[%d]: %p\n", i, graph-&gt;rowPointer[i]); } for(i = 0; i &lt; noOfVertices; i++){ for(j = 0; j &lt; noOfVertices; j++){ Row* row = graph-&gt;rowPointer[i]; fprintf(stdout, "Value of row: %p\n", row); row[j]-&gt;vertex = 0; fprintf(stdout, "Value of row[%d]-&gt;vertex: %d\n", j, row[j]-&gt;vertex); } } return graph; } </code></pre> <p>However my <strong>OUTPUT</strong> is - <br /></p> <blockquote> <p>Value of graph->rowPointer: 003E3C50 <br /> Value of r: 003E3C70 Value of graph->rowPointer[0]: 0028FEDC <br /> Value of r: 003E3C90 <br /> Value of graph->rowPointer[1]: 0028FEDC <br /> Value of r: 003E3CB0 <br /> Value of graph->rowPointer[2]: 0028FEDC <br /> Value of r: 003E3CD0 <br /> Value of graph->rowPointer[3]: 0028FEDC <br /> Value of r: 003E3CF0 <br /> Value of graph->rowPointer[4]: 0028FEDC <br /> Value of row: 0028FEDC <br /> Value of row[0]->vertex: 0 <br /> Value of row: 0028FEDC <br /> Value of row[1]->vertex: 0 <br /> Value of row: 0028FEDC <br /> Value of row[2]->vertex: 0 <br /> Value of row: 0028FEDC <br /></p> </blockquote> <p>and after this the code goes in infinite loop. <br /></p> <p>Thus there seems to be a problem when I assign <code>graph-&gt;rowPointer[i] = &amp;r;</code>, why is this? I think that I have allocated the pointers properly. Can someone tell me what is wrong? <strong>Thanks!</strong></p>
 

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