pulling values from pointers in a loop

Question

getLine is a function that gets a line, I'm trying to combine lines together outside the getLine function. When ever I try doing this in a loop it messes up the output. I bet it has to do with the pointers, but I have spend many hours trying to figure it out.

  int num;
  int matrix[370];

  i=1;
  j=0;
  while(*(point=getLine(infile)) != -2){ 
      n[j]=*point;
      if(n[0] != n[j]){
        printf("matrix dim error 1");
        break;
      }
      while (i<=n[j]){
        matrix[i+(3*j)] = *(point+(i+(3*j)));
        i++;
        printf("%d", matrix[i+(3*j)]);
      }
      printf("%d %d %d\n", matrix[1],matrix[2],matrix[3]);
      j++;
  }
  fclose( infile );
}

int *getLine(FILE *infile){

  int l=0;
  int line[7];
  int i=1;
  int *point;

  while ((l=getNum(infile)) != -1){
    if(l==EOF){
      line[0]=EOF;
      point = &line[0];
      return(point);
    }
    line[i]=l;
    i++;
  }
  if(i==1){
    line[0]=-2;
    point = &line[0];
    return(point);
  }
  line[0]=(i-1); //stores the length of the line in first space
  printf("%d %d %d\n",line[1],line[2],line[3]);
  point = &line[0];
  printf("%d\n",*point);
  return(point);
}

int getNum(FILE *infile) {
  int c=0;
  int value=0;


  while ((c=fgetc(infile)) != '\n') {
    if(c==EOF){
      return(EOF);
    }
    if((c==32)||(c==13)){
      if(value != 0){ //Making sure a number has been gotten
        //printf("%d\n\n", value);
        return(value);
      }
      //otherwise keep getting characters
    }
    else if ((c<=47)||(c>=58)){
      printf("incorrect number input %d\n", c);
      exit(1);
    }
    else {
      value = (10*value) + (c - '0');
    }
  }
  return(-1);//flags that the end of line has been hit
}

Answer 1

Instead of

while (i<=n[j]){

didn't you mean

while (i<=n[j][0]){

More Edit: That's actually ok, i overlook the * in the assignment.

Edit: Some more things:

• there is no check that the range of int is not exceeded in getNum
• there is no check in getLine that more than 7 values are read (which would blow int line[7]
• the matrix calculation in my opinion assumes that there are 3 values read, getLine can deliver up to 7
• matrix[i+(3*j)] = *(point+(i+(3*j))); ?? point is only 7 int big!!! so for the second value it will read beyond defined data. Shouldn't it read matrix[i+(3*j)] = point[i];

hth

Mario

BTW: I strongly recommend:

• resort to std-lib functions
• better naming (i and j in the same source are strongly discouraged)

Answer 2

There is one problem:

int *getLine(FILE *infile){
    int line[7];
    int *point;

    point = &line[0];
    return(point);
}

You return a pointer to a local variable. It becomes invalid when you return from the function. You could allocate it instead on the heap, or let the caller provide it as an argument.