linked-list-test.c

#include <stdio.h>
#include <stdlib.h>

#include "linked-list.h"

#define ASSERT_TRUE(cond) {                                             \
        if (!(cond)) {                                                  \
            fprintf(stderr, "%s: " #cond " assertion failed\n", __func__); \
        }                                                               \
    }

#define ASSERT_EQUALS(a, b) {                                       \
        if ((a) != (b)) {                                           \
            fprintf(stderr, "%s: " #a " != " #b "\n", __func__);    \
        }                                                           \
    }

void test_add() {
    Node *list = NULL;

    Node one = {.val = "one", .next = NULL };
    Node two = {.val = "two", .next = NULL };

    add(&list, &one);
    add(&list, &two);

    ASSERT_EQUALS(length(&list), 2);
    ASSERT_EQUALS(list, &two);
}

void test_head() {
    Node *list = NULL;

    Node one = {.val = "one", .next = NULL};
    Node two = {.val = "two", .next = NULL};
    Node three = {.val = "three", .next = NULL};

    add(&list, &one);
    add(&list, &two);
    add(&list, &three);

    Node *h = head(&list);

    ASSERT_EQUALS(h, &three)
}

void test_tail() {
    Node *list = NULL;

    Node one = {.val = "one", .next = NULL};
    Node two = {.val = "two", .next = NULL};
    Node three = {.val = "three", .next = NULL};

    add(&list, &one);
    add(&list, &two);
    add(&list, &three);

    Node *t = tail(&list);

    ASSERT_EQUALS(t, &one)
}

void test_search() {
    Node *list = NULL;

    Node one = {.val = "one", .next = NULL};
    Node two = {.val = "two", .next = NULL};
    Node three = {.val = "three", .next = NULL};

    add(&list, &one);
    add(&list, &two);
    add(&list, &three);

    char *query = "two";

    Node *r = search(&list, query);

    ASSERT_EQUALS(r, &two)
}

void test_delete() {
    Node *list = NULL;

    Node one = {.val = "one", .next = NULL};
    Node two = {.val = "two", .next = NULL};
    Node three = {.val = "three", .next = NULL};

    add(&list, &one);
    add(&list, &two);
    add(&list, &three);

    ASSERT_EQUALS(3, length(&list));
    ASSERT_EQUALS(three.next, &two);

    delete(&list, &two);

    ASSERT_EQUALS(2, length(&list));
    ASSERT_EQUALS(three.next, &one);
}

int main(void) {
    test_add();
    test_head();
    test_tail();
    test_search();
    test_delete();
}

linked-list.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "linked-list.h"

void print_list(Node **list) {
    Node *p;
    int i = 1;
    for(p = *list; p != NULL; p = p->next) {
        printf("Item[%d] val: %s\n", i++, p->val);
    }
}

void add(Node **list, Node *n) {
    /* add to front of list */
    n->next = *list;
    *list = n;
}

int length(Node **list) {
    Node *p = *list;
    int i = 0;
    while(p) {
        i++;
        p = p->next;
    }
    return i;
}
Node *head(Node **list) {
    return *list;
}

Node *tail(Node **list) {
    Node *p = *list;
    while(p->next != NULL) {
        p = p->next;
    }
    return p;
}
void delete(Node **list, Node *n) {
    Node *p;
    for(p = *list; p != NULL; p = p->next) {
        if (p->next == n) {
            p->next = n->next;
            return;
        }
    }
}

Node *search(Node **list, char *query) {
    Node *p;
    for(p = *list; p != NULL; p = p->next) {
        if (strcmp(p->val, query) == 0) {
            return p;
        }
    }
    return NULL;
}

linked-list.h

typedef struct Node {
    char *val;
    struct Node *next;
} Node;

void print_list(Node **list);
void add(Node **list, Node *n);
int length(Node **list);
Node *head(Node **list);
Node *tail(Node **list);
void delete(Node **list, Node *n);
Node *search(Node **list, char *query);