☜	Numeric Interpretation 1995 Version of ANSI (Equivalent to Current ISO Version) of Standard					☞

7.1.4.5 Numeric interpretation of data

Certain operations, such as arithmetic, deal with the numeric interpretations of their operands. The numeric interpretation is a mapping from the set of all data values into the set of all numeric values, described by the following algorithm. Note that the numeric interpretation maps numeric values into themselves.

(Note: The head of a string is defined to be a substring which contains an identical sequence of characters in the string to the left of a given point and none of the characters in the string to the right of that point. A head may be empty or it may be the entire string.)

Consider the argument to be the string S.

First, apply the following sign reduction rules to S as many times as possible, in any order.

1. If S is of the form + T, then remove the +. (Shorthand: + T T)
2. - + T - T
3. - - T T

Second, apply one of the following, as appropriate.

1. If the leftmost character of S is not "-", form the longest head of S which satisfies the syntax description of numlit. Then apply the algorithm of 7.1.4.4 to the result.
2. If S is of the form - T, apply step a) above to T and append a "-" to the left of the result. If the result is "–0", change it to "0".

The numeric expression numexpr is defined to have the same syntax as expr. Its presence in a syntax description serves to indicate that the numeric interpretation of its value is to be taken when it is executed.

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