From 6a3e59ffeb0234a67854b804b4bee5ba2fb2909c Mon Sep 17 00:00:00 2001
From: sloven-c <marto@marto.si>
Date: Tue, 21 Oct 2025 11:41:43 +0200
Subject: [PATCH] Initial commit

---
 CMakeLists.txt |   6 ++
 main.c         | 169 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 175 insertions(+)
 create mode 100644 CMakeLists.txt
 create mode 100644 main.c

diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 0000000..28bdddd
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,6 @@
+cmake_minimum_required(VERSION 4.0)
+project(hashmap C)
+
+set(CMAKE_C_STANDARD 23)
+
+add_executable(hashmap main.c)
diff --git a/main.c b/main.c
new file mode 100644
index 0000000..c736dbc
--- /dev/null
+++ b/main.c
@@ -0,0 +1,169 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+struct HashMap {
+    char *key, *value;
+    struct HashMap *next;
+};
+
+struct HashMap* init();
+void deinit(struct HashMap *hashmap);
+int insert(struct HashMap *hashmap, char *key, char *value);
+int edit(struct HashMap *hashmap, const char *key, char *value);
+int rem(struct HashMap **hashmap, const char *key);
+char* get(const struct HashMap *hashmap, const char *key);
+void print_all(const struct HashMap *hashmap);
+int maplen(const struct HashMap *hashmap);
+
+int main() {
+    struct HashMap *dict = init();
+    insert(dict, "russia", "east");
+    insert(dict, "india", "south");
+    insert(dict, "slovenia", "center");
+
+    printf("Initial dictionary size: %d\n\n", maplen(dict));
+
+    printf("Printing all pairs:\n");
+    print_all(dict);
+    printf("\n");
+
+    const char *key = "russia";
+    const char *value = get(dict, key);
+    if (value != NULL) printf("'%s' => '%s'\n\n", key, value);
+
+    const int res = rem(&dict, key);
+    if (!res) {
+        printf("Removal of key '%s' succeded. Current size %d\n", key, maplen(dict));
+    } else {
+        printf("Failed to remove the key '%s'\n", key);
+    }
+
+    const char *ekey = "india";
+    char *eval = "bharat";
+    printf("Attempting to change '%s' => '%s'\n", ekey, eval);
+    int eres = edit(dict, ekey, eval);
+    if (!eres) {
+        printf("Change successful!\n");
+    } else {
+        printf("Change failed!\n");
+    }
+    printf("\n");
+
+    printf("Printing all pairs:\n");
+    print_all(dict);
+    printf("\n");
+
+    deinit(dict);
+    return 0;
+}
+
+struct HashMap* init() {
+    struct HashMap* hashmap = malloc(sizeof(struct HashMap));
+    if (hashmap == NULL) {
+        fprintf(stderr, "Failed to allocate the memory to initialise hashmap");
+        exit(1);
+    }
+    hashmap->key = nullptr;
+    hashmap->value = nullptr;
+    hashmap->next = nullptr;
+
+    return hashmap;
+}
+
+void deinit(struct HashMap *hashmap) {
+    if (hashmap == NULL) {
+        return;
+    }
+
+    deinit(hashmap->next);
+    free(hashmap);
+}
+
+int insert(struct HashMap *hashmap, char *key, char *value) {
+    if (get(hashmap, key) != NULL) return 1;
+    bool found_null = false;
+
+    for (struct HashMap *it = hashmap; it != NULL; it = it->next) {
+        if (it->next == NULL) {
+            hashmap = it;
+        }
+
+        if (it->key == NULL && it->value == NULL) {
+            hashmap = it;
+            found_null = true;
+            break; // we found an empty space
+        }
+    }
+
+    if (found_null) {
+        hashmap->key = key;
+        hashmap->value = value;
+        return 0;
+    }
+
+    struct HashMap *new_map = init();
+    new_map->key = key;
+    new_map->value = value;
+    hashmap->next = new_map;
+
+    return 0;
+}
+
+int edit(struct HashMap *hashmap, const char *key, char *value) {
+    for (; hashmap != NULL; hashmap = hashmap->next) {
+        if (hashmap->key == key) {
+            hashmap->value = value;
+            return 0;
+        }
+    }
+
+    return 1;
+}
+
+int rem(struct HashMap **hashmap, const char *key) {
+    struct HashMap *it = *hashmap;
+    struct HashMap *prev = nullptr;
+
+    for (; it != NULL; it = it->next) {
+        if (it->key == key) {
+            // reassign prev pointer to next
+            if (prev != NULL) {
+                prev->next = it->next == NULL ? nullptr : it->next;
+            } else {
+                *hashmap = it->next; // set the caller pointer to point at the non-null element
+            }
+            // clear the pointer
+            free(it);
+            return 0;
+        }
+        prev = it;
+    }
+
+    return 1; // didn't find the pair
+}
+
+char* get(const struct HashMap *hashmap, const char *key) {
+    for (; hashmap != NULL; hashmap = hashmap->next) {
+        if (hashmap->key == key) {
+            return hashmap->value;
+        }
+    }
+
+    return nullptr;
+}
+
+void print_all(const struct HashMap *hashmap) {
+    for (; hashmap != NULL; hashmap = hashmap->next) {
+        printf("'%s': '%s'\n", hashmap->key, hashmap->value);
+    }
+}
+
+int maplen(const struct HashMap *hashmap) {
+    int len = 0;
+
+    for (; hashmap != NULL; hashmap = hashmap->next) {
+        len++;
+    }
+
+    return len;
+}