0

hi guys,

i'm frustrated at my piece of code for a heap sort function. i believe everything is correct but i am a hardcore beginner at c. i have made a rand.txt file with some floats in it in the form;

91.175598

68.562500

96.664803

29.593500

43.156502

34.241001

59.178200

85.542702

81.852798

23.628799

but when i run it, its not reading them numbers and is just writing out 5000 (max array size) values of 0.0000. any ideas what i am doing wrong?

thanks

```
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAXHEAP 100
#define N 5000
typedef char DATA ;
typedef struct heap {
float a[N];
int size;
} HEAP;
float gettop(HEAP *h); /* returns and removes top element from heap */
void insert(HEAP *h, float d); /* inserts d into heap */
int left(HEAP *h,int i); /* computes and returns i's left child index */
int right(HEAP *h,int i); /* computes and returns i's right child index */
int parent(HEAP *h,int i); /* computes and returns i's parent index */
int cmp(float a,float b); /* compares a and b,
returns -1 if(a<b),
returns 0 if(a == b) or
return +1 if(a>b) */
int main(void){
HEAP h;
int i,j;
char buff[BUFSIZ];
float a[N];
FILE *in;
in=fopen("rand.txt","r");
h.size=0; /* empty heap */
for(i=0;i<BUFSIZ;i++){ /* assemble heap */
if(a[i]!=' '){ /* ignore spaces */
insert(&h,(float)a[i]);
printf("%f",a[i]);
}
}
printf("\ncreated heap\n");
/* print heap out */
for(j=0;j<=i;j++){
if(j%20==0){
while(h.size)
printf("%f\n",(float)gettop(&h));
}}
getch();
system("cls");
return 0;
}
int left(HEAP *h,int i){ /* computes and returns i's left child index */
if(i>h->size||i<1){
printf("left: impossible index %d\n",i);
exit(1);
}
if(i*2 > h->size)
return 0; /* i on lowest layer has no left child */
return i*2; /* return index of left child */
}
int right(HEAP *h,int i){ /* computes and returns i's right child index */
if(i>h->size||i<1){
printf("right: impossible index %d\n",i);
exit(1);
}
if(i*2+1 > h->size)
return 0; /* i on lowest layer has no right child */
return i*2+1; /* return index of right child */
}
int parent(HEAP *h,int i){ /* computes and returns i's parent index */
if(i>h->size||i<1){
printf("right: impossible index %d\n",i);
exit(1);
}
if(i==1)
return 0; /* top has no parent */
else
return i/2;
}
int cmp(float a,float b){ /* compares a and b,
returns -1 if(a<b),
returns 0 if(a == b) or
return +1 if(a>b) */
if(a<b) return -1;
else if(a==b) return 0;
else return 1;
}
float gettop(HEAP *h){ /* returns and removes top element from heap */
float top,last;
int i,j,k;
if(h->size == 0){ /* error case for empty heap */
printf("gettop: empty heap\n");
exit(1);
}
top=h->a[1];
if(h->size == 1){ /* special case for heap with only 1 node */
h->size--;
return top; /* heap is now empty */
} else {
/* unlink and store last node in heap */
last=h->a[h->size--];
/* need to rearrange heap following extract, */
i=1;
while(1){
j=left(h,i);
k=right(h,i);
if(j && k){ /* i has both left and right children */
if(cmp(last,h->a[j])<0 &&
cmp(last,h->a[k])<0)
break; /* heap OK so quit loop */
if(cmp(h->a[j],h->a[k])<=0){
/* move hole down to left */
h->a[i]=h->a[j];
i=j;
} else {
/* move hole down to right */
h->a[i]=h->a[k];
i=k;
}
} else if(j){ /* i has a left but no right child */
if(cmp(last,h->a[j])<0)
break; /* heap OK, quit loop */
/* move hole to left */
h->a[i]=h->a[j];
i=j;
} else /* node i now at bottom of heap */
break;
}
/* replace unlinked last node in hole now at lowest layer */
h->a[i]=last;
return top;
}
}
void insert(HEAP *h, float d){ /* inserts d into heap */
int i,j;
if(h->size==0){ /* special case of empty heap */
h->size++;
h->a[1]=d;
} else {
h->size++; /* create hole at bottom of heap */
i=h->size;
while(1){ /* move hole to position where d can be inserted */
j=i;
i=parent(h,i);
if(!i){ /* hole must now be at top so insert here */
h->a[1]=d;
return;
}
if(cmp(d,h->a[i])>=0){
/* heap OK so insert below parent here */
h->a[j]=d;
return;
}
/* bubble parent value down, and hole up */
h->a[j]=h->a[i];
}
}
}
```