added push, need testing

include/stack.h

@@ -3,6 +3,7 @@
 
 #include <cstdint>
 #include <expected>
+#include <new>
 
 #define DEFAULT_STACK_SIZE 4
 
@@ -46,6 +47,31 @@ Stack<T>::~Stack() {
     delete[] this->data;
 }
 
+template <typename T>
+StackErr Stack<T>::push(T value) {
+    // If not enough space allocate more space
+    if (this->len >= this->cap) {
+        uint64_t new_capacity = this->cap * 2;
+        T *tmp;
 
+        try {
+            tmp = new T[new_capacity];
+        } catch (const std::bad_alloc& e) {
+            return StackErr::bad_alloc;
+        }
+
+        for (int i = 0; i < this->len; i++) {
+            tmp[i] = this->data[i];
+        }
+
+        delete[] this->data;
+        this->data = tmp;
+    }
+
+    this->data[this->len] = value;
+    this->len++;
+
+    return StackErr::ok;
+}
 
 #endif // !ST