diff --git a/.gitignore b/.gitignore
index 8808f8b..ee26c71 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,5 @@ main.exe
 .vscode/*
 .vscode/settings.json
 data_file_transaction.txt
+*.gch
+*.o
diff --git a/admin_user.h b/admin_user.h
index 845d470..46ad4ca 100644
--- a/admin_user.h
+++ b/admin_user.h
@@ -44,7 +44,9 @@ void admin_menu(){
         "User control",
         "Role control",
     };
-    switch (choices_selecter(Items,4,strcat("Welcome ")"""%s(%s)\n", user->name,user->role))
+    char welcome[256];
+    sprintf(welcome,"welcome %s(%s)",user->name,user->role);
+    switch (choices_selecter(Items,4,welcome))
     {
         case 1://action with inventory
             inv_control();
@@ -111,29 +113,15 @@ void update_item(struct inventory db,int index);
 void admin_list_pages(struct inventory db);
 struct inventory item_control(struct inventory db,int index);
 
-int prompt_inv_control(){
-    int choice = 0;
-    do{
-        system("cls");
-        printf("Please select an option:\n");
-        printf("1. List(allow all operation include add)\n");
-        printf("2. Add item(shortcut to add item)\n");
-        printf("3. Exit\n");
-        printf(">");
-        scanf("%d", &choice);
-        if(choice < 1 || choice > 3){
-            printf("Invalid choice...press any key to retry....\n");
-            fflush(stdin);
-            getchar();
-        }
-    }while(choice < 1 || choice > 3);
-    return choice;
-}
 
 void inv_control(){
         int choice = 0;
         do{
-        choice = prompt_inv_control();
+        char * items[] = {
+        	"List(allow all operation include add)",
+        	"Add item(shortcut to add item)"
+		};
+        choice = choices_selecter(items,2,NULL);
         switch (choice){
             case 1:;//list
                 //add a new element with product name new item
@@ -157,16 +145,15 @@ void inv_control(){
         }while(choice != 3);
 }
 
-void show_item_admin(struct inventory db,int index){
-    system("cls");
-    printf("Product: %s\n", db.row[index].product);
-    printf("Catergory: %s\n", db.row[index].category);
-    printf("Brand: %s\n", db.row[index].brand);
-    printf("Price: $%lf\n", db.row[index].price);
-    printf("Stock: %d\n", db.row[index].stock);
-    printf("Barcode: %ld\n",db.row[index].barcode);
-    getchar();
-    return;
+char * show_item_admin(struct inventory db,int index){
+	char * output = malloc(sizeof(char) * 1024);
+    sprintf(output,"Product: %s\n", db.row[index].product);
+    sprintf(output,"Catergory: %s\n", db.row[index].category);
+    sprintf(output,"Brand: %s\n", db.row[index].brand);
+    sprintf(output,"Price: $%lf\n", db.row[index].price);
+    sprintf(output,"Stock: %d\n", db.row[index].stock);
+    sprintf(output,"Barcode: %ld\n",db.row[index].barcode);
+    return output;
 }
 
 struct inventory item_control(struct inventory db,int index){
@@ -180,17 +167,17 @@ struct inventory item_control(struct inventory db,int index){
         temp.row[temp.db.row_count - 1].barcode = -1024;//IMPORTANT: -1024 is reserved for new item
         return temp;
     }
+    char * item = show_item_admin(db,index);
+    char welcome[1035];
+    strcpy(welcome,item);
+    strcat(welcome,"Operations");
     do
     {
-        system("cls");
-        show_item_admin(db,index);
-        printf("Operations\n");
-        printf("0 exit\n");
-        printf("1 update item\n");
-        printf("2 remove item\n");
-        printf("Enter your choice: ");
-        fflush(stdin);
-        scanf("%d", &choice);
+        char * items[] = {
+        	"update item",
+        	"remove item"
+		};
+		choice = choices_selecter(item,2,welcome);
         switch (choice)
         {
             case 1:
@@ -202,7 +189,7 @@ struct inventory item_control(struct inventory db,int index){
             default:
                 break;
         }
-    } while (choice != 0&&choice != 2);
+    } while (choice != 3&&choice != 2);
     struct inventory temp = read_db_invt();
     temp.row = (struct inventory_row *)realloc(temp.row, sizeof(struct inventory_row) * (temp.db.row_count + 1));
     temp.db.row_count += 1;
@@ -367,15 +354,11 @@ void tran_control(){
     struct transaction tran = read_db_tran();
     int choice;
     do{
-        system("cls");
-        welcome_message();
-        printf("Transaction control\n");
-        printf("1. List transaction\n");
-        printf("2. new transaction\n");
-        printf("3. Exit\n");
-        printf("Please input your choice: ");
-        fflush(stdin);
-        scanf("%d",&choice);
+        char * items[] = {
+		"List transaction",
+		"new transaction"
+		};
+        choice = choices_selecter(items,2,"><Welcome to the Student Union POS system><\nTransaction control");
         switch(choice){
              case 1:
                 list_tran(tran);
@@ -383,13 +366,7 @@ void tran_control(){
             case 2:
                 add_tran(tran);
                 break;
-            case 3:
-                break;
             default:
-                printf("Invalid input, try again\n");
-                printf("press any key to continue\n");
-                fflush(stdin);
-                getchar();
                 break;
         }
     }while(choice != 3);
@@ -1063,15 +1040,11 @@ void role_control(){
     int choice = -1;
     struct user db = read_db_user();
     do{
-        system("cls");
-        welcome_message();
-        printf("Role control\n");
-        printf("0 exit\n");
-        printf("1 add admin role\n");
-        printf("2 list role\n");
-        printf("Enter choice: ");
-        fflush(stdin);
-        scanf("%d", &choice);
+        char * items[] = {
+        	"add admin role",
+        	"list role"
+		};
+        choice = choices_selecter(items,2,"><Welcome to the Student Union POS system><\nRole control");
         switch (choice){
             case 0:
                 break;
@@ -1082,10 +1055,6 @@ void role_control(){
                 list_role(db);
                 break;
             default:
-                printf("Invalid choice\n");
-                printf("press any key to continue\n");
-                fflush(stdin);
-                getchar();
                 break;
         }
     }while(choice != 0);
diff --git a/main.c b/main.c
index 207532c..1612504 100644
--- a/main.c
+++ b/main.c
@@ -15,26 +15,27 @@
 #include "database.h"
 #endif // !CUSTOM_H
 
-#ifndef MENU_H
-#define MENU_H
-#include "menu.h"
-#endif //MENU_H
 #include "normal_user.h"
 #include "admin_user.h"
-
+#ifndef Utils
+#define Utils
+#include "utils.h"
+#endif // !Utils
 
 
 
 int main(){
     bool check;
-    do
-    {
+    do{
         system("cls");
         //print welcome message
         //prompt weather user is admin or normal user
         //then redirect them to the corisponding menu
-        welcome_message();//refer to menu.h, keep things easier for repeat use on future
-        int choice = user_choices();//same as above
+        char * Items[] = {
+        	"Admin",
+        	"Normal User"
+		};
+        int choice = choices_selecter(Items,2,"><Welcome to the Student Union POS system><\n");
         switch (choice)
         {
         case 1://admin
@@ -45,15 +46,8 @@ int main(){
             normal_menu();//refers to normal_user.h
             check = true;
             break;
-        case 3://exit
+        default://Exit
             check = false;
-            break;
-        default://invalid input
-            printf("Invalid choice...press any key to retry....\n");
-            fflush(stdin);
-            getchar();
-            check = true;
-            
             break;
         }
 
diff --git a/menu.h b/menu.h
deleted file mode 100644
index 2424ba4..0000000
--- a/menu.h
+++ /dev/null
@@ -1,30 +0,0 @@
-//include std lib if they havent been included
-#ifndef STD_LIB_H
-#define STD_LIB_H
-#include<stdio.h>
-#include<stdlib.h>
-#include<string.h>
-#include<stdbool.h>
-#include<math.h>
-#include<time.h>
-#include<ctype.h>
-#endif
-
-
-void welcome_message(){
-    printf("><Welcome to the Student Union POS system><\n");//welcome messgae
-}
-
-int user_choices(){
-    int choice;
-
-    printf("Are you an admin or a normal user?\n");
-    printf("1. Admin\n");
-    printf("2. Normal User\n");
-    printf("3. Exit\n");
-    printf("Enter your choice: ");
-    fflush(stdin);
-    scanf("%d", &choice);
-    
-    return choice;
-}
\ No newline at end of file
diff --git a/normal_user.h b/normal_user.h
index 020d60d..ef4e824 100644
--- a/normal_user.h
+++ b/normal_user.h
@@ -20,24 +20,26 @@
 #include "sorting.h"
 #endif // !SORT_H
 #define PAGE_SIZE 20
-
+#ifndef Utils
+#define Utils
+#include "utils.h"
+#endif // !Utils
 //fucntions for menu
 void list_items();
 void search_item();
 void self_help_sale_system();
 void print_page(struct inventory db, int cur, int end,struct Map* map);
-int normal_menu_user_choices();
 
 //main of normal user
 void normal_menu(){
     int choice = 0;
     do{
-        system("cls");
-        welcome_message();
-        //the selection menu
-        
-        choice = normal_menu_user_choices();
-
+        char * items[] = {
+        	"List items",
+        	"Search item",
+        	"Self help sale system"
+		};
+		choice = choices_selecter(items,3,"><Welcome to the Student Union POS system><\nNormal User Menu");
         switch (choice)
         {
             case 1://List items
@@ -49,10 +51,7 @@ void normal_menu(){
             case 3://self help sale system
                 self_help_sale_system();
                 break;
-            case 4://Exit
-                break;
             default://invalid input ,should not happen,as it is already catch in above function
-                printf("Invalid choice\n");
                 break;
         }
     }while(choice != 4);
@@ -73,18 +72,6 @@ struct inventory show_item(struct inventory db,int index){
     getchar();
     return db;
 }
-int normal_menu_user_choices(){
-    int choice;
-    printf("Normal User Menu\n");
-    printf("1. List items\n");
-    printf("2. Search item\n");
-    printf("3. Self help sale system\n");
-    printf("4. Exit\n");
-    printf("Enter your choice: ");
-    fflush(stdin);
-    scanf("%d", &choice);
-    return choice;
-}
 
 //user for showing list result and search result
 void list_page(struct inventory db,struct Map* map,int row,struct inventory (*showitem)(struct inventory,int)){//showitem is a function pointer for showing item,allow customization for better flexibilty  
@@ -253,8 +240,7 @@ struct Map* sortItems(struct inventory db, int sort){
 char* prompt_search();
 struct Map* searchItems(struct inventory db, char* searchstr);
 void search_item(){
-    system("cls");
-    welcome_message();
+
     //search for item
     //prompt user to select an item
     //if user selects an item, display the item's details
@@ -264,24 +250,11 @@ void search_item(){
 
     //options
     int breakout = 0;
-    bool valid = false;
-    do{
-        system("cls");
-        welcome_message();
-        printf("0 exit\n");
-        printf("1 search\n");
-        printf("select your choice: ");
-        fflush(stdin);
-        scanf("%d", &breakout);
-        fflush(stdin);
-        if(breakout == 1 || breakout == 0){
-            valid = true;
-        }else{
-            valid = false;
-            printf("Invalid choice\n");
-        }
-    }while(!valid);
-    if(breakout == 0){
+    char * items[] = {
+    	"search"
+	};
+    breakout = choices_selecter(items,1,"><Welcome to the Student Union POS system><");
+    if(breakout == 2){
         break;
     }
     char* searchstr = prompt_search();
@@ -309,28 +282,7 @@ char* prompt_search(){
     scanf("%s", searchstr);
     return searchstr;
 }
-//check if strcasestr is define in current environment
-//if not, define it
-#ifndef HAVE_STRCASESTR
-char *strcasestr(const char *s, const char *find)
-{
-char c, sc;
-size_t len;
 
-if ((c = *find++) != 0) {
-c = tolower((unsigned char)c);
-len = strlen(find);
-do {
-do {
-if ((sc = *s++) == 0)
-return (NULL);
-} while ((char)tolower((unsigned char)sc) != c);
-} while (strncasecmp(s, find, len) != 0);
-s--;
-}
-return ((char *)s);
-}
-#endif
 
 
 struct Map* searchItems(struct inventory db, char* searchstr){
@@ -353,59 +305,37 @@ struct Map* searchItems(struct inventory db, char* searchstr){
 
 //self help
 
-
-int self_choice();
 struct cart* scan_barcode(struct cart* cart,struct inventory db);
 struct cart* list_cart(struct cart* cart);
 void self_help_sale_system(){
-    system("cls");
-    welcome_message();
+ 
     //scan barcode
     struct inventory db = read_db_invt();
     struct cart* cart = NULL;
-    bool check = false;
+    int choice = 0;
     do{
 
     //options
     int breakout = 0;
-    int choice = self_choice();
-    check = false;
+    char * items[] = {
+    	"scan barcode",
+    	"cart/checkout"
+	};
+    choice = choices_selecter(items,2,"><Welcome to the Student Union POS system><");
     switch (choice)
     {
     case 1:
         cart = scan_barcode(cart,db);
-        check = true;
         break;
     case 2:
         cart = list_cart(cart);
-        check = true;
         break;
     default:
         break;
     }
-    }while(check);
+    }while(choice!=3);
 }
 
-int self_choice(){
-    int choice = 0;
-    bool valid = false;
-    do{
-        system("cls");
-        welcome_message();
-        printf("0 exit\n");
-        printf("1 scan barcode\n");
-        printf("2 cart/checkout\n");
-        printf("select an option: ");
-        fflush(stdin);
-        scanf("%d", &choice);
-        if(choice <= 2 || choice >= 0){
-            valid = true;
-        }else{
-            printf("Invalid choice\n");
-        }
-    }while(!valid);
-    return choice;
-}
 //support for the linked list
 struct cart* Cartappend(struct cart* cart,struct inventory_row* row,int quantity){
     if(cart == NULL){
@@ -621,20 +551,17 @@ struct cart* cart_control(struct cart* cart,int index){
     struct inventory_row* row = Cartget(cart,index-1);
     int quantity = Cartqty(cart,index-1);
     do{
-        system("cls");
-        welcome_message();
-        printf("0 exit\n");
-        printf("1 remove\n");
-        printf("2 edit quantity\n");
-        printf("product: %s\n",row->product);
-        printf("price: %.1f\n",row->price);
-        printf("quantity: %d\n",quantity);
-        bool check;
-        do{
-            check = true;
-            printf("select an option: ");
-            fflush(stdin);
-            scanf("%d", &choice);
+        char welcome[256];
+        sprintf(welcome,"><Welcome to the Student Union POS system><\n");
+        sprintf(welcome,"product: %s\n",row->product);
+        sprintf(welcome,"price: %.1f\n",row->price);
+        sprintf(welcome,"quantity: %d\n",quantity);
+        char * items[] = {
+        	"remove",
+        	"edit quantity"
+		};
+		choice = choices_selecter(items,2,welcome);
+
             if(choice == 1){
                 cart = Cartremove(cart,index-1);
                 printf("Remove successful\n");
@@ -647,12 +574,8 @@ struct cart* cart_control(struct cart* cart,int index){
                 printf("press any key to continue");
                 fflush(stdin);
                 getchar();
-            }else if(choice != 0){
-                printf("Invalid choice\n");
-                check = false;
             }
-        }while(!check);
-    }while(choice < 0 || choice > 2);
+    }while(choice != 1 || choice != 2 || choice !=3 );
     return cart;
 }
 
diff --git a/utils.h b/utils.h
index 79438eb..576f5a8 100644
--- a/utils.h
+++ b/utils.h
@@ -1,9 +1,22 @@
-int choices_selecter(char * Items[],int items,char * welcome_message ){
+#ifndef STD_LIB_H
+#define STD_LIB_H
+#include<stdio.h>
+#include<stdlib.h>
+#include<string.h>
+#include<stdbool.h>
+#include<math.h>
+#include<time.h>
+#include<ctype.h>
+#include <stddef.h>
+#endif
+
+int choices_selecter(char * Items[],int items,char * welcome_messages ){
   int choice = 0;
   do{
   	system("cls");
-    if ((*welcome_message) !=NULL){
-    	printf("%s",welcome_message)
+
+    if (welcome_messages !=NULL){
+    	printf("%s",welcome_messages);
 	}
 	printf("Select An Option:\n");
     int i;
@@ -12,6 +25,8 @@ int choices_selecter(char * Items[],int items,char * welcome_message ){
     }
     printf("%d. Exit\n",i+1);
     printf(">");
+  	fflush(stdin);
+    scanf("%d",&choice);
     if(choice < 1 || choice > items+1){
         printf("Invalid choice...press any key to retry....\n");
         fflush(stdin);
@@ -21,3 +36,25 @@ int choices_selecter(char * Items[],int items,char * welcome_message ){
   return choice;
 
 } 
+//check if strcasestr is define in current environment
+//if not, define it
+#ifndef HAVE_STRCASESTR
+char *strcasestr(const char *s, const char *find)
+{
+char c, sc;
+size_t len;
+
+if ((c = *find++) != 0) {
+c = tolower((unsigned char)c);
+len = strlen(find);
+do {
+do {
+if ((sc = *s++) == 0)
+return (NULL);
+} while ((char)tolower((unsigned char)sc) != c);
+} while (strncasecmp(s, find, len) != 0);
+s--;
+}
+return ((char *)s);
+}
+#endif