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POSegmentation Fault - GNU C
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2013-07-24T12:52:07.653
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I've been getting a segmentation fault that I cannot figure out. The function that causes the segmentation fault is shown below: <pre><code>Expression *IntegerLiteral_init(int intgr) { Expression *the_exp = safe_alloc(sizeof(Expression)); the_exp->type = expr_IntegerLiteral; the_exp->expr->intgr = intgr; the_exp->exec_count = 0; return the_exp; } </code></pre> An Expression is defined: <pre><code>typedef struct { expr_type type; u_expr *expr; int exec_count; } Expression; </code></pre> u_expr and expr_type are defined: <pre><code>typedef union { char *ident; int intgr; } u_expr; typedef enum { expr_Identifier, expr_IntegerLiteral } expr_type; </code></pre> <code>expr_type</code> is an enum of <code>expr_IntegerLiteral</code> and <code>expr_Identifier</code>. According to GDB, the segfault is caused on the line: <code>the_exp->expr->intgr = intgr;</code>. Strangely, it does not always cause a segfault - a segfault occurs if I call the function in this manner: <pre><code>Expression *e = IntegerLiteral_init(0); </code></pre> But in another part of my program, I call it using: <pre><code>Expression *e; ... e = IntegerLiteral_init( (int)strtol(num_str, (char **)NULL, 10)); </code></pre> which works without any problem. <code>num_str</code> has been parsed from some input and has the value <code>"0"</code>. I don't understand why the context in which I call <code>IntegerLiteral_init()</code> should affect whether or not this segfault occurs, if the given <code>intgr</code> parameter is the same. If anyone could shed any light on this, I would be most grateful.
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<c><segmentation-fault><gnu>
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Segmentation Fault - GNU C
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