All wroking fine, too tired to make tests, everything seems fine

src/main.cpp

@@ -1,7 +1,106 @@
+#include "queue.h"
+#include "utils.h"
 #include <cstdlib>
 #include <print>
 
+void menu(Queue<int> queue);
+
 int main(void) {
-    std::println("Hola");
+    Queue<int> queue = {};
+
+    menu(queue);
     return EXIT_SUCCESS;
 }
+
+void menu(Queue<int> queue) {
+    while (true) {
+        clear_screen();
+        std::println("---Queue Manager---");
+        std::println("1) Enqueue.");
+        std::println("2) Dequeue.");
+        std::println("3) Peek.");
+        std::println("4) Diplay.");
+        std::println("5) Exit.");
+        int choice;
+
+        if (!read_int("", &choice)) {
+            std::println("Invalid input.");
+            wait_enter();
+            continue;
+        }
+
+        clear_screen();
+        switch (choice) {
+            case 1: {
+                int input;
+
+                if (!read_int("Type the integer to enqueue:\n", &input)) {
+                    std::println("Invalid input.");
+                    wait_enter();
+                    continue;
+                }
+
+                if (queue.enqueue(input) == QueueErr::bad_alloc) {
+                    std::println("Program couldn't allocate memory for queue.");
+                    wait_enter();
+                    continue;
+                }
+
+                std::println("Integer {} was correclty enqueued.", input);
+                wait_enter();
+                break;
+                }
+            case 2: {
+                auto out = queue.dequeue();
+                if (!out.has_value() && out.error() == QueueErr::empty) {
+                    std::println("The queue is empty.");
+                    wait_enter();
+                    continue;
+                } else if (!out.has_value() && out.error() == QueueErr::bad_alloc) {
+                    std::println("Program couldn't allocate memory for queue");
+                    wait_enter();
+                    continue;
+                }
+
+                std::println("The element at the tail was {}.", out.value());
+                wait_enter();
+                break;
+            }
+            case 3: {
+                auto out = queue.peek();
+                if (!out.has_value() && out.error() == QueueErr::empty) {
+                    std::println("The queue is empty.");
+                    wait_enter();
+                    continue;
+                } else if (!out.has_value() && out.error() == QueueErr::bad_alloc) {
+                    std::println("Program couldn't allocate memory for queue");
+                    wait_enter();
+                    continue;
+                }
+
+                std::println("The element at the tail was {}.", out.value());
+                wait_enter();
+                break;
+
+                }
+            case 4: {
+                queue.print();
+                wait_enter();
+                break;
+                }
+            case 5: {
+                std::println("Goodbye :)");
+                wait_enter();
+                clear_screen();
+                exit(1);
+                }
+            default: {
+                std::println("Invalid option.");
+                wait_enter();
+                clear_screen();
+                break;
+                }
+
+        }
+    }
+}

src/utils.cpp

@@ -0,0 +1,129 @@
+#include "utils.h"
+#include <limits.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+
+void clear_screen() {
+    printf("\033[2J\033[H");
+    fflush(stdout);
+}
+
+void wait_enter() {
+    int c;
+    printf("Press Enter to continue...");
+    fflush(stdout);
+
+    while ((c = getchar()) != '\n' && c != EOF) {
+        ;
+    }
+}
+
+void sleep_seconds(size_t s) {
+    #ifdef _WIN32
+        #include <windows.h>
+        Sleep(s * 1000);
+    #else 
+        // #include <unistd.h>
+        // sleep(s); 
+    #endif /* ifdef _WIN32
+         */
+}
+
+void read_string(const char *message, char **dest) {
+    if (!dest) {
+        return;
+    }
+
+    printf("%s", message);
+
+    char buffer[256]; // I mean, should be enough
+    if (!fgets(buffer, sizeof(buffer), stdin))
+        return;
+
+    buffer[strcspn(buffer, "\n")] = '\0';
+
+    char *tmp = static_cast<char *>(malloc(strlen(buffer) + 1));
+    if (!tmp) {
+        return;
+    }
+
+    strcpy(tmp, buffer);
+
+    free(*dest);
+    *dest = tmp;
+}
+
+int read_int(const char *message, int *dest) {
+    char buffer[64];
+    char *end;
+    long value;
+
+    printf("%s", message);
+    fflush(stdout);
+
+    if (!fgets(buffer, sizeof(buffer), stdin)) {
+        return 0;
+    }
+
+    errno = 0;
+    value = strtol(buffer, &end, 10);
+
+    if (errno != 0) {
+        return 0;
+    }
+
+    if (end == buffer) {
+        return 0;
+    }
+
+    if (*end != '\n' && *end != '\0') {
+        return 0;
+    }
+
+    if (value < INT_MIN || value > INT_MAX) {
+        return 0;
+    }
+
+    *dest = (int)value;
+    return 1;
+}
+
+int read_double(const char *message, double *dest) {
+    char buffer[64];
+    char *end;
+    double value;
+
+    printf("%s", message);
+    fflush(stdout);
+
+    if (!fgets(buffer, sizeof(buffer), stdin)) {
+        return 0;
+    }
+
+    errno = 0;
+    value = strtod(buffer, &end);
+
+    if (errno != 0) {
+        return 0;
+    }
+
+    if (end == buffer) {
+        return 0;
+    }
+
+    if (*end != '\n' && *end != '\0') {
+        return 0;
+    }
+
+    if (!isfinite(value)) {
+        return 0;
+    }
+
+    *dest = value;
+    return 1;
+}