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POPointer value changed in XML parse start handler
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copied!<p>I have an int pointer that for some reason has its value being modified as soon as it is passed out of the main. This file is using the expat XML_Parse command. Here is the relevant code:</p> <p>The struct that I set the values in:</p> <pre><code>struct song_data { float *freq_array; int *freq_array_count; int *freq_duration_array; }; </code></pre> <p>Part of (most of) main:</p> <pre><code>int main(int argc, char **argv) { const int BUFFER_SIZE = 8192; char buffer[BUFFER_SIZE]; struct song_data * wav = (struct song_data *)malloc(sizeof(struct song_data)); *wav->freq_array_count=0; XML_Parser parser = XML_ParserCreate(NULL); //create parser XML_SetElementHandler(parser, start, end); XML_SetUserData(parser, &wav); FILE *xml_file = fopen(argv[1], "r"); int done = 0; while (!done) { int length = fread(buffer, sizeof(char), BUFFER_SIZE, xml_file); done = feof(xml_file); XML_Parse(parser, buffer, length, done); } </code></pre> <p>And the start handler:</p> <pre><code>void start(void *data, const char *tag, const char **attributes) { struct song_data *song_data = (struct song_data *) data; printf("in start, freq_array_count=%d\n,*song_data->freq_array_count); // rest of code } </code></pre> <p>The printf in the start handler prints some weird value like -7194902 or something (the server I was working on is currently down). </p> <p>Another approach that I have tried (and would prefer, if I can figure out how to get it working) is having the <code>int *freq_array_count</code> just be an int (<code>int freq_array_count</code>)... however this also gets a weird value immediately the first time the start handler is called (something above 100,000,000)</p> <p>Why? I feel as if the int value, in the approach taken here, should not be modified because it is pointing to a part of memory I explicitly asked for.</p> <p>In the other approach it shouldn't be modified either because the int belongs to the struct on the heap, and thus should not be modified. </p> <p>Why is this happening?</p>

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