Pointer problems with structures

This is a discussion on Pointer problems with structures within the C Programming forums, part of the General Programming Boards category; I am making a program that needs to make an array of linked list, but I keep getting an error ...

  1. #1
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    Question Pointer problems with structures

    I am making a program that needs to make an array of linked list, but I keep getting an error that says dereferencing pointer to incomplete type at the point when I am trying to set value to temp. My code is:
    Code:
    #include <stdio.h>
    #include <stdbool.h>
    
    typedef struct //list node
    {
     char destination;
     struct NODE* next;
    
    }NODE;
    
     typedef struct  //linked list
    {
     char startingPoint;
     struct NODE* first;
    
    }LIST;
    
    void fillStruct(char* fileName,LIST map[]);
    void printList();
    void depthSearch();
    void breadth();
    void topoSort();
    NODE* ListIterator(NODE* start);
    
    void fillStruct(char* fileName,LIST map[]){
    char points[60];
    FILE* fpIn;
    int i=0;
    char readIn=' ';
    int j=0;
    struct NODE* temp;
    
    for(j=0;j<60;j++)
    points[j]=' ';
    
    if((fpIn=fopen(fileName,"r"))!=NULL)
    do{
    
    readIn=getc(fpIn);
    if(readIn!=EOF && readIn>='A')
    points[i++]=readIn;
    
    }while(readIn<'A' && readIn!=EOF);
    
    for(j=0;points[j]!=' ';j+=2){
    if(map[(int)points[j]-65].startingPoint==' ')
    map[(int)points[j]-65].startingPoint=points[j];
    temp->destination=points[j+1];
    temp->next=NULL;
    if(map[(int)points[j]-65].first==NULL)
    map[(int)points[j]-65].first=temp;
    else{
    ListIterator(map[(int)points[j]-65].first)->next=temp;
    //last->next=temp;
    }
    
    }
    I know the structure declarations may look a little weird, but that is how my compiler requires them. Any help on what is wrong with my code will be greatly appreciated.

  2. #2
    Registered User claudiu's Avatar
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    Temp does not point to anything and has no memory allocated for it.

  3. #3
    and the Hat of Guessing tabstop's Avatar
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    14,185
    At no point do you ever declare something called "struct NODE", so you really shouldn't be trying to keep pointers to that type. You should probably give your node type that name, so that you can use it. (I.e., it should say "struct NODE", not just "struct".)

  4. #4
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    I could have sworn I had tried that but obviously not because it just worked.
    Thanks a bunch

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