read-char

read

R Functions

read-line

 

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read-char

Returns the decimal ASCII code representing the character read from the keyboard input buffer or from an open file

(read-char [file-desc]) 

Arguments

file-desc

A file descriptor (obtained from open) referring to an open file. If no file-desc is specified, read-char obtains input from the keyboard input buffer.

Return Values

An integer representing the ASCII code for a character. The read-char function returns a single newline character (ASCII code 10) whenever it detects an end-of-line character or character sequence.

Examples

The following example omits file-desc, so read-char looks for data in the keyboard buffer:

Command: (read-char)

The keyboard buffer is empty, so read-char waits for user input:

      ABC
    

65

The user entered ABC; read-char returned the ASCII code representing the first character entered (A). The next three calls to read-char return the data remaining in the keyboard input buffer. This data translates to 66 (the ASCII code for the letter B), 67 (C), and 10 (newline), respectively:

Command: (read-char)

66

Command: (read-char)

67

Command: (read-char)

10

With the keyboard input buffer now empty, read-char waits for user input the next time it is called:

Command: (read-char)