edit_string_v1.c

/*

    edit_string_v1.c                by Dragan Milicev

    Edit a string in a single line using the left arrow, right arrow,
    home, end, backspace, insert and enter keys.


    Ascii table:

    characters_0    0 -  31   special characters

    characters_1   32 -  47

    0 - 9    48 -  57   digits

    characters_2   58 -  64

    A - Z    65 -  90   capital letters

    characters_3   91 -  96

    a - z    97 - 122   small letters

    characters_4  123 - 126


    You can find all my C programs at Dragan Milicev's pastebin:

    https://pastebin.com/u/dmilicev

*/

#include <stdio.h>
#include <string.h>
#include <windows.h>        // tracking cursor all the time, for cursor position functions
                            // gotoxy(x,y) , wherex() , wherey(), showcursor(), hidecursor()

#define CTRL_Z          26  // keys Ctrl + Z
#define CTRL_X          24  // keys Ctrl + X
#define CTRL_C           3  // keys Ctrl + C
#define CTRL_V          22  // keys Ctrl + V
#define BACKSPACE        8  // key Backspace
#define TAB              9  // key Tab
#define ENTER           13  // key Enter
#define ESC             27  // Escape key
#define UP              72  // up arrow
#define DOWN            80  // down arrow
#define LEFT            75  // left arrow
#define RIGHT           77  // right arrow
#define PG_UP           73  // Page Up key
#define PG_DOWN         81  // Page Down down key
#define HOME            71  // Home key
#define END             79  // End key
#define DEL             83  // Delete key
#define INSERT          82  // Insert key


// ----------CURSOR CONTROL FUNCTIONS------------------------------------------

// make console cursor invisible
void hidecursor()
{
   HANDLE consoleHandle = GetStdHandle(STD_OUTPUT_HANDLE);
   CONSOLE_CURSOR_INFO info;
   info.dwSize = 20;
   info.bVisible = FALSE;
   SetConsoleCursorInfo(consoleHandle, &info);
}

// make console cursor invisible
void showcursor()
{
   HANDLE consoleHandle = GetStdHandle(STD_OUTPUT_HANDLE);
   CONSOLE_CURSOR_INFO info;
   info.dwSize = 20;
   info.bVisible = TRUE;
   SetConsoleCursorInfo(consoleHandle, &info);
}

// make console cursor invisible
void bigcursor()
{
   HANDLE consoleHandle = GetStdHandle(STD_OUTPUT_HANDLE);
   CONSOLE_CURSOR_INFO info;
   info.dwSize = 100;
   info.bVisible = TRUE;
   SetConsoleCursorInfo(consoleHandle, &info);
}

// place cursor at position ( x, y ) = ( row, column )
void gotoxy( int x, int y )
{
    COORD coord;

    coord.X = x;
    coord.Y = y;

    SetConsoleCursorPosition( GetStdHandle(STD_OUTPUT_HANDLE), coord );
}

// return x coordinate (column) of current cursor position
// on failure return -1
int wherex()
{
    CONSOLE_SCREEN_BUFFER_INFO csbi;

    if (!GetConsoleScreenBufferInfo( GetStdHandle(STD_OUTPUT_HANDLE), &csbi ) )
        return -1;

    return csbi.dwCursorPosition.X;
}

// return y coordinate (row) of current cursor position
// on failure return -1
int wherey()
{
    CONSOLE_SCREEN_BUFFER_INFO csbi;

    if (!GetConsoleScreenBufferInfo( GetStdHandle( STD_OUTPUT_HANDLE ), &csbi ) )
        return -1;

    return csbi.dwCursorPosition.Y;
}

// END OF-----CURSOR CONTROL FUNCTIONS------------------------------------------


// ----------TEXT FOREGROUND AND BACKGROUND COLOR CONTROL FUNCTIONS-------------

void SetColorAndBackground(int ForgC, int BackC)
{
     WORD wColor = ((BackC & 0x0F) << 4) + (ForgC & 0x0F);;
     SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), wColor);
     return;
} //SetColorAndBackground()

// END OF----TEXT FOREGROUND AND BACKGROUND COLOR CONTROL FUNCTIONS--------------


// Edit a string in a single line using the left arrow, right arrow,
// home, end, backspace, insert and enter keys.
char *edit_string( int x, int y, int fc, int bc, char str[] )
{
    int i, c_choice, len, memX, insert_flag=1;
    char *s;                                    // to copy str to s

    s = malloc( strlen(str) + 257 );            // reserve the memory space for copy and edit str

    if( s == NULL )                             // checking whether memory reallocation succeeded
    {
        fprintf(stderr, "\n\n malloc() for s error! \n\n");
        exit(EXIT_FAILURE);
    }

    strcpy(s,str);                              // copy str to s
    gotoxy(x,y);
    SetColorAndBackground(fc,bc);               // set colors to foreground and background colors
    printf("%s", s);

    while( 1 ) {                                // an infinite loop that exits with Enter or Escape

        c_choice = _getch();                    // read  the keyboard

        switch( c_choice  ) {                   // scroll items and switch choice

            case BACKSPACE :                    // if Backspace key is pressed
                    if(wherex()>x)
                    {
                        memX = wherex();
                        len = strlen(s);
                        for(i=memX-x-1; i<len; i++) // moving the characters to the left
                            s[i] = s[i+1];
                        s[i] = '\0';            // finish the new string s
                        gotoxy(x,y);            // erase last print of string s
                        SetColorAndBackground(7,0); // reset colors to system default colors
                        for(i=0; i<len; i++)
                            printf(" ");
                        gotoxy(x,y);            // print string s
                        SetColorAndBackground(fc,bc); // set colors to foreground and background colors
                        printf("%s", s);
                        gotoxy(memX-1,y );
                    }
                    break;
            case ENTER :                        // if Enter key is pressed, exit from editing and return(s)
                    SetColorAndBackground(7,0); // reset colors to system default colors

                    if( strlen(str) < strlen(s) )   // check memory space to copy s to str
                    {
                        realloc(str, strlen(s)+1);  // realloc the memory space to copy s to str

                        if( str == NULL )       // Checking whether memory reallocation succeeded
                        {
                            fprintf(stderr, "\n\n realloc() for str error! \n\n");
                            exit(EXIT_FAILURE);
                        }
                    }
                    strcpy(str,s);
                    free(s);                    // free memory space reserved for s
                    showcursor();
                    return(str);
                    break;
            case ESC :                          // if Escape key is pressed, exit from editing and return(0)
                    SetColorAndBackground(7,0); // reset colors to system default colors
                    free(s);                    // free memory space reserved for s
                    showcursor();
                    return(str);                // return original string str
                    break;
            case  0  :                          // if pressed a function key
            case 224 :                          // if pressed a special function key,
                    c_choice = _getch();        // let's empty that 0 or 224 and
                                                // analyze which function key is pressed
                    if( c_choice == LEFT )      // if pressed left arrow
                    {
                        if(wherex()>x)
                            gotoxy(wherex()-1,y );
                    } // if( c_choice == LEFT )

                    if( c_choice == RIGHT )     // if pressed right arrow
                    {
                        if(wherex()<x+strlen(s))
                            gotoxy(wherex()+1,y );
                    } // if( c_choice == RIGHT )

                    if( c_choice == HOME )      // if Home key is pressed
                    {
                        gotoxy(x,y);
                    } // if( c_choice == HOME )

                    if( c_choice == END )       // if End key is pressed
                    {
                        gotoxy(x+strlen(s),y );
                    } // if( c_choice == END )

                    if( c_choice == INSERT )    // if Insert key is pressed
                    {
                        if( insert_flag )
                            insert_flag = 0;
                        else
                            insert_flag = 1;

                        if( insert_flag )
                            showcursor();
                        else
                            bigcursor();
                    } // if( c_choice == INSERT )

                    if( c_choice == DEL )       // if Delete key is pressed
                    {
                        if(wherex()>=x)
                        {
                            memX = wherex();
                            len = strlen(s);
                            for(i=memX-x; i<len; i++)   // moving the characters to the left
                                s[i] = s[i+1];
                            s[i] = '\0';        // finish the new string s
                            gotoxy(x,y);        // erase last print of string s
                            SetColorAndBackground(7,0); // reset colors to system default colors
                            for(i=0; i<len; i++)
                                printf(" ");
                            gotoxy(x,y);        // print string s
                            SetColorAndBackground(fc,bc); // set colors to foreground and background colors
                            printf("%s", s);
                            gotoxy(memX,y );
                        }
                    } // if( c_choice == DEL )

                    break;
            default:
                    if( c_choice >= 32 && c_choice <= 126 )
                    {
                        if ( insert_flag )      // to insert a character to string s
                        {
                            memX = wherex();
                            len = strlen(s);
                            for(i=len+2; i>=memX-x; i--) // moving the characters from end to the right
                                s[i+1] = s[i];
                            s[memX-x] = c_choice;   // new character
                            gotoxy(x,y);        // erase last print of string s
                            for(i=0; i<len; i++)
                                printf(" ");
                            gotoxy(x,y);        // print the new string s
                            printf("%s", s);
                            gotoxy(memX+1,y );
                        } // if ( insert_flag )
                        else                    // to overwrite a character to string s
                        {
                            memX = wherex();
                            len = strlen(s);
                            s[memX-x] = c_choice;   // new character
                            s[len+1] = '\0';
                            gotoxy(x,y);        // erase last print of string s
                            for(i=0; i<len; i++)
                                printf(" ");
                            gotoxy(x,y);        // print the new string s
                            printf("%s", s);
                            gotoxy(memX+1,y );
                        } // else // to overwrite a character to string s
                    } // if( ... )

                    break;
        } // switch( c_choice )
    } // while( 1 )
} // edit_string()


int main(void)
{
    int x=10, y=5, fc=9, bc=11;

    char str[] = "This is string to be edited.";

    gotoxy(x-1,y-2);
    printf("|%s|", str);

    edit_string( x, y, fc, bc, str );

    gotoxy(x-1,y+2);
    printf("|%s| \n\n", str);


    return 0;

} // main()