The addch, waddch, mvaddch and mvwaddch routines put the character ch into the given window at its current window position, which is then advanced. They are analogous to putchar in stdio(3). If the advance is at the right margin, the cursor automatically wraps to the beginning of the next line. At the bottom of the current scrolling region, if scrollok is enabled, the scrolling region is scrolled up one line.
If ch is a tab, newline, or backspace, the cursor is moved appropriately within the window. Backspace moves the cursor one character left; at the left edge of a window it does nothing. Newline does a clrtoeol, then moves the cursor to the window left margin on the next line, scrolling the window if on the last line). Tabs are considered to be at every eighth column.
If ch is any control character other than tab, newline, or backspace, it is drawn in ^X notation. Calling winch after adding a control character does not return the character itself, but instead returns the ^-representation of the control character.
Video attributes can be combined with a character argument passed to addch or related functions by logical-ORing them into the character. (Thus, text, including attributes, can be copied from one place to another using inch and addch.). See the curs_attr(3X) page for values of predefined video attribute constants that can be usefully ORed into characters.
The echochar and wechochar routines are equivalent to a call to addch followed by a call to refresh, or a call to waddch followed by a call to wrefresh. The knowledge that only a single character is being output is used and, for non-control characters, a considerable performance gain may be seen by using these routines instead of their equivalents.
The following variables may be used to add line drawing characters to the screen with routines of the addch family. The default character listed below is used if the acsc capability doesnt define a terminal-specific replacement for it (but see the EXTENSIONS section below). The names are taken from VT100 nomenclature.