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IMPLEMNTATION OF TEXT EDITOR IN C

AIM:

To write a c program that implemnts a basic command line text editor.

ALGORITHM:

1. Read the given file and display the content.

2. Move the cursor to top left position.

3. Set to edit mode.

4. Incase of edit mode, set various commands such as h,j,k,u as left, down, right, up

respectively to move the cursor.

5. Let I transfer to input mode , xx to delete the current cha, d to delete the current

line .L to refresh, w to save and exit, q to exit and o to go to new line and

insert.

6. In input mode, type in whatever the user enters onto the screen.

7. CTRL+D returns to edit mode.

CODE:

#include #include

#define CTRL(c) ((c) & 037)

/* Global value of current cursor position */

int row, col;

int main(int argc,char **argv){

extern void perror(), exit();

int i, n, l;

int c;

int line = 0;

FILE *fd;

if (argc != 2)

{

fprintf(stderr, "Usage: %s file\n", argv[0]);exit(1);

}

fd = fopen(argv[1], "r");

if (fd == NULL)

{

perror(argv[1]);

exit(2);

}

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initscr();

cbreak();

nonl();

noecho();

idlok(stdscr, TRUE);keypad(stdscr, TRUE);

/* Read in the file */

while ((c = getc(fd)) != EOF)

{

if (c == '\n')

line++;

if (line > LINES - 2)

break;

addch(c);

}

fclose(fd);

move(0,0);refresh();

edit();

/* Write out the file */fd = fopen(argv[1], "w");

for (l = 0; l < LINES - 1; l++)

{

n = len(l);

for (i = 0; i < n; i++)

putc(mvinch(l, i) & A_CHARTEXT, fd);

putc('\n', fd);

}fclose(fd);

endwin();

return 0;

}

len(int lineno)

{

int linelen = COLS - 1;

while (linelen >= 0 && mvinch(lineno, linelen) == ' ')

linelen--;return linelen + 1;

}

edit()

{

int c;

while(1)

{

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move(row, col);

refresh();

c = getch();

/* Editor commands */switch (c)

{

/* hjkl and arrow keys: move cursor

* in direction indicated */

case 'h':

case KEY_LEFT:

if (col > 0)

col--;

else

flash();

break;

case 'j':case KEY_DOWN:

if (row < LINES - 1)

row++;

elseflash();

break;

case 'k':

case KEY_UP:

if (row > 0)

row--;

elseflash();

break;

case 'l':

case KEY_RIGHT:

if (col < COLS - 1)

col++;

else

flash();

break;/* i: enter input mode */

case KEY_IC:case 'i':

input();

break;

/* x: delete current character */

case KEY_DC:

case 'x':

delch();

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break;

/* o: open up a new line and enter input mode */

case KEY_IL:

case 'o':move(++row, col = 0);

insertln();input();

break;

/* d: delete current line */

case KEY_DL:

case 'd':

deleteln();

break;

/* ^L: redraw screen */

case KEY_CLEAR:

case CTRL('L'):wrefresh(curscr);

break;

/* w: write and quit */case 'w':

return;

/* q: quit without writing */

case 'q':

endwin();

exit(2);

default:

flash();break;

}

}

}

/*

* Insert mode: accept characters and insert them.

* End with D or EIC

*/

input(){

int c;

standout();

mvaddstr(LINES - 1, COLS - 20, "INPUT MODE");

standend();

move(row, col);

refresh();

for (;;)

{

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c = getch();

if (c == CTRL('D') || c == KEY_EIC)

break;

insch(c);

move(row, ++col);refresh();

}move(LINES - 1, COLS - 20);

clrtoeol();

move(row, col);

refresh();

}

OUTPUT:

Enter I to goto input mode.

Enter the text HELLO.

Press CTRL+D to exit the input mode, use arrow marks to move around.Hit w to save and exit.

Inp.txt

HELLO

RESLUT:

Thus the C program that implemnts a simple command line text editor is written and

executed successfully.