Searching through a linked list. - c

Question

So i've been trying to understand the difference between a regularly defined structure without using malloc linked list that does utilize malloc.
The issue that i'm having right now is trying to search through the structure (pi) to find each part number that has a cost greater than what was entered into the search. this is my entire program so far. I've added comments for each section.
I'm simply not sure how i am suppose to search through each structure to compare its price to the search price.
#include <stdio.h>
#include <stdlib.h>
struct Item {
int quantity;
float cost;
char partNum[10];
struct Item *next;
};
void printItem(struct Item* pi);
void enterItem(struct Item* pi);
char search [100];
void main(int argc, char* argv[])
{
struct Item *pi;
struct Item *head;
int done = 0;
int i,j;
char choice;
// ENTERING ITEM INTO THE STRUCTURE
head = NULL;
while (!done) {
printf("Enter another item? (y/n)");
choice = getchar();
if (choice == 'y' || choice == 'Y') {
pi = (struct Item *)malloc(sizeof(struct Item));
enterItem(pi);
pi->next = head;
head = pi;
} else {
done = 1;
}
}
// SEARCHING FOR ITEM BY PRICE
printf("Enter a price to find all items more expensive, or type 'exit':");
while (strcmp(search, "exit") !=0) {
gets(search);
for (j = 0; j<i ; i++) {
if (strcmp(pi[j].cost, search) ==0) {
printItem(pi);
pi = pi->next;
}
}
}
}
getchar();
getchar();
}
// FUNCTION FOR PRINTING STRUCTURE ITEM
void printItem(struct Item* pi) {
printf("Quantity: %d\n", pi->quantity);
printf("Cost: $%.2f\n", pi->cost);
printf("Part # %s\n", pi->partNum);
printf("\n\n");
}
// FUNCITON FOR ENTERING IN NEW ITEM
void enterItem(struct Item* pi) {
printf("Quantity? ");
scanf("%d", &pi->quantity);
printf("Cost? ");
scanf("%f", &pi->cost);
getchar(); //need to clear out the carriage return from typeing in the cost
printf("Part Number? ");
gets(pi->partNum);
}

Answer 1

What you were doing wrong is comparing string(search variable) with a float(cost variable) using strcmp. This won't give you the desired output.
Instead, lets use -1 to indicate the exit, since parsing string and converting it to float is off-topic. Start iterating from head up to finding NULL, and compare the prices of the each item.
float price;
struct Item *it = head;
printf("Enter a price to find all items more expensive, or type '-1' to exit:");
scanf("%f", price);
// check price for the 'exit' -- compare with -1
while (it != NULL) {
if (it->cost > price)
printItem(pi);
it = it->next;
}