C POINTERS - CIRCULAR DOUBLY LINKED LIST

A Simple Selection Menu in C with Ansi functions. 
This time I'm working on creating a circular list with pointers so as to display choice menus in C using colors to highlight the items. 

In my implementation, I have used 3 external global pointers (head, former and tail). That probably means that I can only create one list as these pointers are global variables.

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <termios.h> #include <unistd.h> #include <sys/ioctl.h> /* Last modified : 19/9/2017 Coded by Velorek. Some of the terminal routines from: https://stackoverflow.com/questions/7469139/what-is-equivalent-to-getch-getche-in-linux Circular linked list to make a selection menu in C. Target OS: Linux. */ // Background colors low intensity #define B_BLACK 40 #define B_RED 41 #define B_GREEN 42 #define B_YELLOW 43 #define B_BLUE 44 #define B_MAGENTA 45 #define B_CYAN 46 #define B_WHITE 47 // Foreground colors low intensity #define F_BLACK 30 #define F_RED 31 #define F_GREEN 32 #define F_YELLOW 33 #define F_BLUE 34 #define F_MAGENTA 35 #define F_CYAN 36 #define F_WHITE 37 // Background colors high intensity #define BH_BLACK 100 #define BH_RED 101 #define BH_GREEN 102 #define BH_YELLOW 103 #define BH_BLUE 104 #define BH_MAGENTA 105 #define BH_CYAN 106 #define BH_WHITE 107 // Foreground colors high intensity #define FH_BLACK 90 #define FH_RED 91 #define FH_GREEN 92 #define FH_YELLOW 93 #define FH_BLUE 94 #define FH_MAGENTA 95 #define FH_CYAN 96 #define FH_WHITE 97 #define TRUE 1 #define FALSE 0 typedef int BOOL; /* Global Variables */ struct winsize max; static struct termios old, new; int rows, columns, old_rows, old_columns; typedef struct _listchoice { int index; // Item number int backcolor0; // Back and Fore colors when not selected int forecolor0; int backcolor1; // Back and Fore colors when selected int forecolor1; int wherex; // Position of the item int wherey; char *item; // Item string struct _listchoice *next; // Pointer to next item struct _listchoice *back; // Pointer to previous item. } LISTCHOICE; LISTCHOICE *head=NULL; LISTCHOICE *tail=NULL; LISTCHOICE *former=NULL; LISTCHOICE *mylist=NULL; /* Terminal manipulation routines */ void gotoxy(int x,int y) //Sets the cursor at the desired position. { printf("%c[%d;%df",0x1B,y,x); } void outputcolor(int foreground, int background) //Changes format foreground and background colors of display. { printf("%c[%d;%dm", 0x1b,foreground,background); } void screencol(int x) { //change color of entire screen gotoxy(0,0); outputcolor(0,x); printf("%c[2J", 0x1b); outputcolor(0,0); } /* Initialize new terminal i/o settings */ void initTermios(int echo) { tcgetattr(0, &old); /* grab old terminal i/o settings */ new = old; /* make new settings same as old settings */ new.c_lflag &= ~ICANON; /* disable buffered i/o */ new.c_lflag &= echo ? ECHO : ~ECHO; /* set echo mode */ tcsetattr(0, TCSANOW, &new); /* use these new terminal i/o settings now */ } /* Restore old terminal i/o settings */ void resetTermios(void) { tcsetattr(0, TCSANOW, &old); } /* Read 1 character - echo defines echo mode */ char getch_(int echo) { char ch; initTermios(echo); ch = getchar(); resetTermios(); return ch; } /* Read 1 character without echo */ char getch(void) { return getch_(0); } /* Read 1 character with echo */ char getche(void) { return getch_(1); } int get_terminal_dimensions(int *rows, int *columns) { //Get dimensions of screen by value. ioctl(0, TIOCGWINSZ , &max); *columns = max.ws_col; *rows = max.ws_row; return 0; } /* Dynamic List routines */ void add_item(LISTCHOICE *list_identifier, char *str, int x, int y,int bcolor0, int fcolor0, int bcolor1, int fcolor1) { LISTCHOICE *newp; if (head == NULL && list_identifier == NULL) { //Reserve memory list_identifier = (LISTCHOICE *) malloc(sizeof(LISTCHOICE)); head = list_identifier; tail = list_identifier; //Create first item of the list and assign properties to it. list_identifier->backcolor0 = bcolor0; list_identifier->backcolor1 = bcolor1; list_identifier->forecolor0 = fcolor0; list_identifier->forecolor1 = fcolor1; list_identifier->wherex = x; list_identifier->wherey = y; list_identifier-> item = (char *)malloc(strlen(str) +1); strcpy(list_identifier->item, str); list_identifier->next = head; list_identifier->back = head; list_identifier->index = 0; } else { //Circular list structure newp = (LISTCHOICE *) malloc(sizeof(LISTCHOICE)); former = tail; //former pointer points to previous-last item former->next = newp; //previous item forward points to current item newp->back = former; //new item back points to previous-last item tail = newp; //the tail now 'becomes' (points to) the new item head->back = tail; // This way we close the circular list : First item back points to last item tail->next = head; // Last item next points to first item. //Creates subsequent items of the list and assign properties to it. newp->backcolor0 = bcolor0; newp->backcolor1 = bcolor1; newp->forecolor0 = fcolor0; newp->forecolor1 = fcolor1; newp->wherex = x; newp->wherey = y; newp->item = (char*) malloc(strlen(str) + 1); strcpy(newp->item, str); newp->index = former->index + 1; } } void free_list(LISTCHOICE *list_identifier) { /* removes list from memory */ LISTCHOICE *aux, *p; aux = tail; do { p=aux; aux = aux->back; free(p->item); //free off the string field free(p); //remove item } while (aux != head->back); } void move_up(LISTCHOICE *aux) { //Unmark Former Item gotoxy(aux->wherex,aux->wherey); outputcolor(aux->forecolor0,aux->backcolor0); printf("%s\n", aux->item); //Highlight current item *aux=*aux->back; //Go to previous item gotoxy(aux->wherex,aux->wherey); outputcolor(aux->forecolor1,aux->backcolor1); printf("%s\n", aux->item); } void move_down(LISTCHOICE *aux) { //Unmark Former Item gotoxy(aux->wherex,aux->wherey); outputcolor(aux->forecolor0,aux->backcolor0); printf("%s\n", aux->item); //Highlight current item *aux=*aux->next; //Go to next item gotoxy(aux->wherex,aux->wherey); outputcolor(aux->forecolor1,aux->backcolor1); printf("%s\n", aux->item); } void display_list() { /* Displays the items contained in the list with the properties specified in init_list. until the auxiliary pointer reaches the first item again First item is equal to tail->next. */ LISTCHOICE *aux; aux = head; do { gotoxy(aux->wherex,aux->wherey); outputcolor(aux->forecolor0,aux->backcolor0); printf("%s\n", aux->item); aux = aux->next; } while (aux != tail->next); } void start_vmenu(LISTCHOICE *list_data) { /* Starts the selection menu */ char ch; LISTCHOICE aux; display_list(); //display whole list //Highlight first item on the list aux=*tail; //Auxiliary variable points to last item move_down(&aux); //Move down to point to highlight first item. ch=0; // reset and initialise ch value while (ch != 10) // enter key { ch=getch(); if (ch=='\033') // escape key { getch(); // read key again for arrow key combinations switch(getch()) { case 'A': // escape key + A => arrow key up move_up(&aux); break; case 'B': // escape key + B => arrow key down move_down(&aux); break; } } } if (ch==10) // enter key { //Pass data of last item by value. *list_data = aux; } } int main_screen() { //Draws the main screen int i,j; //Draw the main screen rows=0; columns=0; screencol(B_BLUE); gotoxy(1,1); outputcolor(0,F_WHITE); //Save previous values old_rows = rows; old_columns = columns; get_terminal_dimensions(&rows,&columns); if (rows==0) rows=25; //just in case it can't find the terminal dimensions if (columns==0) columns=80; //Draw upper and lower bars outputcolor(F_WHITE,B_CYAN); for (i=0;i<=columns;i++) { gotoxy(i,1); printf(" "); } outputcolor(F_WHITE,B_WHITE); for (i=0;i<=columns;i++) { gotoxy(i,rows); printf(" "); } outputcolor(F_BLACK,B_CYAN); gotoxy(1,1); printf(" File Options Help"); outputcolor(FH_WHITE,B_BLUE); gotoxy(2,3); printf("Selection Menu"); gotoxy(2,4); printf("=============="); gotoxy(columns-6,1); outputcolor(FH_YELLOW,B_CYAN); printf("%d:%d",columns,rows); outputcolor(F_BLACK,B_WHITE); gotoxy(1,rows); printf("- Coded by Velorek"); } int main() { LISTCHOICE data; screencol(FH_BLUE); main_screen(); add_item(mylist,"Option 1",3,6,B_BLUE,FH_WHITE,B_RED,F_WHITE); add_item(mylist,"Option 2",3,7,B_BLUE,FH_WHITE,B_RED,F_WHITE); add_item(mylist,"Option 3",3,8,B_BLUE,FH_WHITE,B_RED,F_WHITE); add_item(mylist,"Option 4",3,9,B_BLUE,FH_WHITE,B_RED,F_WHITE); add_item(mylist,"Option 5",3,10,B_BLUE,FH_WHITE,B_RED,F_WHITE); add_item(mylist,"Exit",3,11,B_BLUE,FH_WHITE,B_GREEN,F_WHITE); outputcolor(F_BLUE,B_BLACK); do { start_vmenu(&data); gotoxy(20,18); printf("You have selected: %i:%s\n",data.index+1,data.item); } while (strcmp(data.item,"Exit") != 0); free_list(mylist); screencol(B_BLACK); printf("\n"); return 0; }

 Display:

We Love Colors - ANSI Functions II in C

You have several options to give your program a more attractive look in text-mode. Ncurses,for one, in Linux is an excellent choice. But if you want to keep it simple and do things fast, you can resort to using ANSI escape sequences. They work like a charm on Linux terminals. Unfortunately, its support was removed from Windows terminals. Although I hear Windows 10 has brought back support to these sequences. Alternatively, check Ansicon for windows support. 

From Wikipedia:

In C:

int gotoxy(int x,int y)
//Sets the cursor at the desired position.
{
  printf("%c[%d;%df",0x1B,y,x);
  return 0;
}

int outputcolor(int foreground, int background)
//Changes format foreground and background colors of display.
{
  printf("%c[%d;%dm", 0x1b,foreground,background);
  return 0;
}

int screencol(int x)
// Changes color of the entire screen.
{
  gotoxy(0,0);
  outputcolor(0,x);
  printf("%c[2J", 0x1b);
  outputcolor(0,0);
  return 0;
}