c - Can't find the error in this code. (SIGSEGV) -

i writing method (c - language) should create new node linked list. crashes @ line after first if (sigsegv signal)

i debugging method there more errors in subsequent lines, moment appreciate observations regarding particular line.

//create new tequivalencenode tequivalencenode* createnewequivalencenode(twordequivalence e){     //create new equivalence node     tequivalencenode* node = null;     node = (tequivalencenode*) malloc(sizeof(tequivalencenode));     //allocate memory both srcword , dstword      twordinfo* destiny = null;     twordinfo* source = null;     destiny = (twordinfo*) malloc(sizeof(twordinfo));     source = (twordinfo*) malloc(sizeof(twordinfo));      if((node != null)&&(destiny != null) && (source != null)){         node->elem->dstword = destiny; //crashes @ line          node->elem->srcword = source;         //copy information destiny word in new node         node->elem->dstword->languageid = e.dstword->languageid;         node->elem->dstword->wordid = e.dstword->wordid;         //allocate memory word , copy string node         node->elem->dstword->word = (char*) malloc((strlen(e.dstword->word) + 1)*sizeof(char));         if(node->elem->dstword->word != null){             strcpy(node->elem->dstword->word, e.dstword->word);         }          //repeat process source word         node->elem->srcword->languageid = e.srcword->languageid;         node->elem->srcword->wordid = e.srcword->wordid;         //allocate memory word , copy string node         node->elem->srcword->word = (char*) malloc((strlen(e.srcword->word) + 1)*sizeof(char));         if(node->elem->srcword->word != null){             strcpy(node->elem->srcword->word, e.srcword->word);         }          node->next = null;     }     return node; } 

this definition of twordinfo data type:

/* dictionary word */ typedef struct {     int languageid;     int wordid;     char* word; } twordinfo; 

tequivalencenode:

/* equivalences list element */ typedef struct tequivalencenode tequivalencenode; struct tequivalencenode{     /* ex 1.1 */     twordequivalence* elem;      tequivalencenode* next; }; 

and twordequivalence:

typedef struct {     /* word in source language */     twordinfo* srcword;      /* equivalent word in destination language */     twordinfo* dstword;  } twordequivalence; 

if((node != null)&&(destiny != null) && (source != null)){     node->elem->dstword = destiny; //crashes @ line  

crashes because node->elem not initialized. node->elem->dstword dereferencing garbage pointer.

you want initialize new memory block:

node = (tequivalencenode*) malloc(sizeof(tequivalencenode)); node->elem = (twordequivalence*) malloc(sizeof(twordequivalence)); // ... 

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for record, simplify things (and wouldn't have had problem) if put twordequivalence directly tequivalencenode instead of using pointer:

struct tequivalencenode{     twordequivalence elem;      tequivalencenode* next; };