diff --git a/data_structures/list_array.cpp b/data_structures/list_array.cpp
index 0c8099f578..d53af391ec 100644
--- a/data_structures/list_array.cpp
+++ b/data_structures/list_array.cpp
@@ -46,7 +46,7 @@ struct list {
      * @param val element that will be searched
      * @return index of element in the list if present else -1
      */
-    uint64_t BinarySearch(const std::array<uint64_t, N> &dataArr,
+    int64_t BinarySearch(const std::array<uint64_t, N> &dataArr,
                           const uint64_t &first, const uint64_t &last,
                           const uint64_t &val) {
         // If both pointer cross each other means no element present in the list
@@ -77,7 +77,7 @@ struct list {
      * @param val element that will be searched
      * @return index of element in the list if present else -1
      */
-    uint64_t LinearSearch(const std::array<uint64_t, N> &dataArr,
+    int64_t LinearSearch(const std::array<uint64_t, N> &dataArr,
                           const uint64_t &val) const {
         // Going through each element in the list
         for (uint64_t i = 0; i < top; i++) {
@@ -94,8 +94,8 @@ struct list {
      * @param val element that will be searched
      * @return index of element in the list if present else -1
      */
-    uint64_t search(const uint64_t &val) {
-        uint64_t pos;  // pos variable to store index value of element.
+    int64_t search(const uint64_t &val) {
+        int64_t pos;  // pos variable to store index value of element.
         // if list is sorted, binary search works efficiently else linear search
         // is the only option
         if (isSorted) {
@@ -181,7 +181,7 @@ struct list {
      * @returns void
      */
     void remove(const uint64_t &val) {
-        uint64_t pos = search(val);  // search the index of the value
+        int64_t pos = search(val);  // search the index of the value
         // if search returns -1, element does not present in the list
         if (pos == -1) {
             std::cout << "\n Element does not present in the list ";
diff --git a/data_structures/queue_using_array.cpp b/data_structures/queue_using_array.cpp
index c243725832..80d8b048b3 100644
--- a/data_structures/queue_using_array.cpp
+++ b/data_structures/queue_using_array.cpp
@@ -57,13 +57,13 @@ class Queue_Array {
  * @param ele to be added to the end of the queue
  */
 void Queue_Array::enqueue(const int16_t& ele) {
-    if (rear == arr.size() - 1) {
+    if (rear == static_cast<int>(arr.size()) - 1) {
         std::cout << "\nStack is full";
     } else if (front == -1 && rear == -1) {
         front = 0;
         rear = 0;
         arr[rear] = ele;
-    } else if (rear < arr.size()) {
+    } else if (rear < static_cast<int>(arr.size())) {
         ++rear;
         arr[rear] = ele;
     }
diff --git a/data_structures/trie_tree.cpp b/data_structures/trie_tree.cpp
index b7b4ce5fd5..feb2c038bd 100644
--- a/data_structures/trie_tree.cpp
+++ b/data_structures/trie_tree.cpp
@@ -54,7 +54,7 @@ class trie {
      * @returns `false` if not found
      */
     bool search(const std::shared_ptr<trie>& root, const std::string& str,
-                int index) {
+                size_t index) {
         if (index == str.length()) {
             if (!root->isEndofWord) {
                 return false;
@@ -104,7 +104,7 @@ class trie {
      * @returns `true` if found
      * @returns `false` if not found
      */
-    bool search(const std::string& str, int index) {
+    bool search(const std::string& str, size_t index) {
         if (index == str.length()) {
             if (!isEndofWord) {
                 return false;
@@ -131,7 +131,7 @@ class trie {
      * @returns `true` if successful
      * @returns `false` if unsuccessful
      */
-    bool deleteString(const std::string& str, int index) {
+    bool deleteString(const std::string& str, size_t index) {
         if (index == str.length()) {
             if (!isEndofWord) {
                 return false;