\section{Arithmetic And Expressions} \label{Arithmetic And Expressions} The numeric argument of a TECO command may consist of a single integer, any of the characters listed in Table~\ref{Characters Associated With Numeric Quantities}, the numeric contents of any Q-register, or an arithmetic combination of these elements. If an arithmetic expression is supplied as a numeric argument, TECO will evaluate the expression. All arithmetic expressions are evaluated from left to right without any operator precedence. Parentheses may be used to override the normal order of evaluation of an expression. If parentheses are used, all operations within the parentheses are performed, left to right, before operations outside the parentheses. Parentheses may be nested, in which case the innermost expression contained by parentheses will be evaluated first. Table~\ref{Arithmetic Operators} lists all of the arithmetic operators that may be used in arithmetic expressions. \begin{table}[h] \caption{\bf Arithmetic Operators} \label{Arithmetic Operators} \end{table} \nopagebreak \begin{tabular}{lll} \multicolumn{1}{c}{OPERATOR} & \multicolumn{1}{c}{EXAMPLE} & \multicolumn{1}{c}{FUNCTION} \\ {\tt +} & {\tt +2=2} & Ignored if used before the first term in an \\ & & expression. \\ {\tt +} & {\tt 5+6=11} & Addition, if used between terms. \\ {\tt -} & {\tt -2=-2} & Negation, if used before the first term in an \\ & & expression. \\ {\tt -} & {\tt 8-2=6} & Subtraction, if used between terms \\ {\tt *} & {\tt 8*2=16} & Multiplication. Used between terms. \\ {\tt /} & {\tt 8/3=2} & Integer division with loss of the remainder. \\ & & Used between terms. \\ {\tt \&} & {\tt 12\&10=8} & Bitwise logical AND of the binary \\ & & representation of the two terms. Used \\ & & between the terms. \\ {\tt \#} & {\tt 12\#10=14} & Bitwise logical OR of the binary of the two \\ & & terms. Used between the terms. \\ \caret {\tt \_} & & {\tt 5}\caret {\tt \_=-6} Unary one's complement. Used after an \\ & & expression. This is a TECO command that \\ & & complements its argument. Strictly speaking, \\ & & it is not a unary operator. \\ \end{tabular} \begin{table}[h] \caption{\bf Conversion And Radix Control Commands} \label{Conversion And Radix Control Commands} \end{table} \nopagebreak \begin{list}{}{\labelsep 20pt} \item[{\em COMMAND}] {\em FUNCTION} \item[{\tt n=}] This command causes the value of {\tt n} to be output at the terminal in decimal followed by a carriage return and line feed. Decimal numeric conversion is signed. For example, the unsigned number 65535 will output as -1 on TECO-11. TECO's radix is unaltered. \item[{\tt n==}] This command causes the value of {\tt n} to be output at the terminal in octal (base 8) followed by a carriage return and line feed. Octal numeric conversion is unsigned. For example, the unsigned number 8191 (decimal) will output as 17777 on TECO-8. TECO's radix is unaltered. \iftecoelevenonly \item[{\tt n===}] This command causes the value of {\tt n} to be output at the terminal in hexadecimal (base 16) followed by a carriage return and line feed. Hexadecimal output is unsigned. TECO's radix is unaltered. {\em [TECO-11 only]} \fi \item[{\tt n:=}] \item[{\tt n:==}] \item[{\tt n:===}] These commands are equivalent to {\tt n=}, {\tt n==}, and {\tt n===}, except that they leave the carriage positioned at the end of the output. \item[\caret {\tt O}] {\tt } (caret/O) causes all subsequent numeric input to be accepted as octal numbers. Numeric conversions using the \bs or {\tt n}\bs commands will also be octal. The digits 8 and 9 become illegal as numeric characters. The octal radix will continue to be used until the next \caret {\tt D} command is executed or until TECO's radix is changed by an {\tt n}\caret {\tt R} command. {\em NOTE: On TECO-10, this command only affects the immediately following digit string.} \ifnotintecoten \item[\caret {\tt D}] {\tt } (\caret{\tt D}) causes all subsequent numeric input to be accepted as decimal numbers. This is the initial setting. {\em [Not in TECO-10]} \fi \iftecoelevenonly \item[\caret{\tt R}] This command returns the binary value of TECO's current radix. {\em [TECO-11 only]} \fi \item[{\tt n}\caret{\tt R}] This command sets TECO's radix to the value of {\tt n}. It is currently implemented only in TECO-11, where {\tt n} may only be one of the values 8, 10, or 16 (representing octal mode, decimal mode, or hexadecimal mode). If {\tt n} is not one of these values, TECO's radix remains unchanged and the {\tt ?IRA} error message is produced. \item[{\tt \bs}] A backslash character which is not preceded by a numeric argument causes TECO to evaluate the digit string (if any) beginning with the character immediately following the buffer pointer and ending at the next character that is not valid for the current radix. The value becomes the numeric argument of the next command. The first character may be a digit or {\tt +} or {\tt -}. As the backslash command is evaluated, TECO moves the buffer pointer to a position immediately following the digit string. If there is no digit string following the pointer, the result is zero and the pointer position remains unchanged. Except on TECO-8, the digits 8 and 9 will stop the evaluation if TECO's current radix is octal. \item[{\tt n\bs}] The backslash command preceded by an argument inserts the value of {\tt n} into the text buffer at the current position of the pointer, leaving the pointer positioned after the last digit of the insertion. The insertion is either signed decimal (decimal radix), unsigned octal (octal radix), or unsigned hexadecimal (hexadecimal radix). Note that \bs is a {\em bidirectional} command. {\tt \bs} inserts a string into text while \bs (no argument) returns a numeric result. \end{list}