Advanced Programming Guide

364 • Appendix A: Internal Representation and ManipulationStop MapleSTOPMaple syntax: quit, done, or stopLength: 1StringSTRING reserved ∧ attrib − expr characters characters . . .Maple syntax: "This is a string"Length: 4 or moreA Maple string is structurally similar to a NAME, except that it hasno assigned-value field. The attrib-expr field points to an expressionsequence of attributes of the string. If there are no attributes, this fieldpoints to the empty expression sequence (NULL). The remaining fieldscontain the characters making up the string, stored 4 or 8 per machineword (for 32-bit and 64-bit architectures respectively). The last characteris followed by a zero-byte. Any unused bytes in the last machine word arealso zero.The maximum length of a string is 268, 435, 447 characters on 32-bitarchitectures and 34, 359, 738, 351 characters on 64-bit architectures.Sum, DifferenceSUM ∧ expr ∧ factor ∧ expr ∧ factor . . . . . .Maple syntax: expr * factor + expr * factor ...Length: 2n + 1This structure is interpreted as pairs of expressions and their numericfactors. Rational or integer expressions with an integer factor are expandedand the factor replaced with 1. If there is a rational constant inthe sum, this constant is moved to the first entry by the simplifier. Simpleproducts, such as a*2, are represented as SUMs. More complex productsinvolving non-numeric factors are represented as PROD structures.TableTABLE ∧ index − func ∧ array − bounds ∧ hash − tab