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- Sep 3, 2018, 8:35:55 AM (6 years ago)
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- ADT, aaron-thesis, arm-eh, ast-experimental, cleanup-dtors, deferred_resn, enum, forall-pointer-decay, jacob/cs343-translation, jenkins-sandbox, master, new-ast, new-ast-unique-expr, no_list, persistent-indexer, pthread-emulation, qualifiedEnum
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doc/user/user.tex
re255e69 rba80f99 11 11 %% Created On : Wed Apr 6 14:53:29 2016 12 12 %% Last Modified By : Peter A. Buhr 13 %% Last Modified On : Thu Jul 26 17:29:05201814 %% Update Count : 33 6613 %% Last Modified On : Fri Aug 31 07:54:50 2018 14 %% Update Count : 3396 15 15 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 16 16 … … 210 210 Even with all its problems, C continues to be popular because it allows writing software at virtually any level in a computer system without restriction. 211 211 For system programming, where direct access to hardware, storage management, and real-time issues are a requirement, C is usually the only language of choice. 212 The TIOBE index~\cite{TIOBE} for July 2018 ranks the top 5 most \emph{popular} programming languages as:\Index*{Java} 16\%, C 14\%, \Index*[C++]{\CC{}} 7.5\%, Python 6\%, Visual Basic 4\% = 47.5\%, where the next 50 languages are less than 4\% each, with a long tail.212 The TIOBE index~\cite{TIOBE} for July 2018 ranks the top five most \emph{popular} programming languages as \Index*{Java} 16\%, C 14\%, \Index*[C++]{\CC{}} 7.5\%, Python 6\%, Visual Basic 4\% = 47.5\%, where the next 50 languages are less than 4\% each, with a long tail. 213 213 The top 3 rankings over the past 30 years are: 214 214 \begin{center} … … 351 351 The 2011 C standard plus GNU extensions. 352 352 \item 353 \Indexc[deletekeywords=inline]{-fgnu89-inline}\index{compilation option!-fgnu89-inline@{\lstinline[deletekeywords=inline] @-fgnu89-inline@}}353 \Indexc[deletekeywords=inline]{-fgnu89-inline}\index{compilation option!-fgnu89-inline@{\lstinline[deletekeywords=inline]$-fgnu89-inline$}} 354 354 Use the traditional GNU semantics for inline routines in C11 mode, which allows inline routines in header files. 355 355 \end{description} … … 455 455 #endif 456 456 457 ®#include_next <bfdlink.h> 457 ®#include_next <bfdlink.h> §\C{// must have internal check for multiple expansion}§ 458 458 ® 459 459 #if defined( with ) && defined( __CFA_BFD_H__ ) §\C{// reset only if set}§ … … 504 504 505 505 C, \CC, and Java (and many other programming languages) have no exponentiation operator\index{exponentiation!operator}\index{operator!exponentiation}, \ie $x^y$, and instead use a routine, like \Indexc{pow}, to perform the exponentiation operation. 506 \CFA extends the basic operators with the exponentiation operator ©?\?©\index{?\\?@ \lstinline@?\?@} and ©?\=?©\index{?\\=?@\lstinline@?\=?@}, as in, ©x \ y© and ©x \= y©, which means $x^y$ and $x \leftarrow x^y$.506 \CFA extends the basic operators with the exponentiation operator ©?\?©\index{?\\?@©?\?©} and ©?\=?©\index{?\\=?@©\=?©}, as in, ©x \ y© and ©x \= y©, which means $x^y$ and $x \leftarrow x^y$. 507 507 The priority of the exponentiation operator is between the cast and multiplicative operators, so that ©w * (int)x \ (int)y * z© is parenthesized as ©((w * (((int)x) \ ((int)y))) * z)©. 508 508 … … 516 516 256 64 -64 0.015625 -0.015625 18.3791736799526 0.264715-1.1922i 517 517 \end{cfa} 518 Parenthesis are necessary for the complex constants or the expression is parsed as ©1.0f+(2.0fi \ 3.0f)+2.0fi©.518 Parenthesis are necessary for complex constants or the expression is parsed as ©1.0f+®(®2.0fi \ 3.0f®)®+2.0fi©. 519 519 The exponentiation operator is available for all the basic types, but for user-defined types, only the integral-computation versions are available. 520 520 For returning an integral value, the user type ©T© must define multiplication, ©*©, and one, ©1©; … … 527 527 528 528 529 %\subsection{\texorpdfstring{\protect\lstinline@if@ Statement}{if Statement}} 530 \subsection{\texorpdfstring{\LstKeywordStyle{if} Statement}{if Statement}} 531 532 The ©if© expression allows declarations, similar to ©for© declaration expression: 533 \begin{cfa} 534 if ( int x = f() ) ... §\C{// x != 0}§ 535 if ( int x = f(), y = g() ) ... §\C{// x != 0 \&\& y != 0}§ 536 if ( int x = f(), y = g(); ®x < y® ) ... §\C{// relational expression}§ 537 \end{cfa} 538 Unless a relational expression is specified, each variable is compared not equal to 0, which is the standard semantics for the ©if© expression, and the results are combined using the logical ©&&© operator.\footnote{\CC only provides a single declaration always compared not equal to 0.} 529 %\subsection{\texorpdfstring{\protect\lstinline@if@/\protect\lstinline@while@ Statement}{if Statement}} 530 \subsection{\texorpdfstring{\LstKeywordStyle{if}/\LstKeywordStyle{while} Statement}{if/while Statement}} 531 532 The ©if©/©while© expression allows declarations, similar to ©for© declaration expression. 533 (Does not make sense for ©do©-©while©.) 534 \begin{cfa} 535 if ( ®int x = f()® ) ... §\C{// x != 0}§ 536 if ( ®int x = f(), y = g()® ) ... §\C{// x != 0 \&\& y != 0}§ 537 if ( ®int x = f(), y = g(); x < y® ) ... §\C{// relational expression}§ 538 if ( ®struct S { int i; } x = { f() }; x.i < 4® ) §\C{// relational expression}§ 539 540 while ( ®int x = f()® ) ... §\C{// x != 0}§ 541 while ( ®int x = f(), y = g()® ) ... §\C{// x != 0 \&\& y != 0}§ 542 while ( ®int x = f(), y = g(); x < y® ) ... §\C{// relational expression}§ 543 while ( ®struct S { int i; } x = { f() }; x.i < 4® ) ... §\C{// relational expression}§ 544 \end{cfa} 545 Unless a relational expression is specified, each variable is compared not equal to 0, which is the standard semantics for the ©if©/©while© expression, and the results are combined using the logical ©&&© operator.\footnote{\CC only provides a single declaration always compared not equal to 0.} 539 546 The scope of the declaration(s) is local to the @if@ statement but exist within both the ``then'' and ``else'' clauses. 547 548 549 %\subsection{\texorpdfstring{\protect\lstinline@for@ Statement}{for Statement}} 550 \subsection{\texorpdfstring{\LstKeywordStyle{for} Statement}{for Statement}} 551 552 The ©for©/©while©/©do-while© loop-control allows empty or simplified ranges. 553 An empty conditional implies ©1©. 554 The up-to range ©~©\index{~@©~©} means exclusive range [M,N); 555 the up-to range ©~=©\index{~=@©~=©} means inclusive range [M,N]. 556 The down-to range ©-~©\index{-~@©-~©} means exclusive range [N,M); 557 the down-to range ©-~=©\index{-~=@©-~=©} means inclusive range [N,M]. 558 ©0© is the implicit start value; 559 ©1© is the implicit increment value for an up-to range and ©-1© for an implicit down-to range. 560 The loop index is polymorphic in the type of the start value or comparison value when start is implicitly ©0©. 561 \begin{cquote} 562 \begin{tabular}{@{}ll|l@{}} 563 \multicolumn{2}{c|}{for control} & \multicolumn{1}{c}{output} \\ 564 \hline 565 \begin{cfa} 566 while ®()® { sout | "empty"; break; } 567 do { sout | "empty"; break; } while ®()®; 568 for ®()® { sout | "empty"; break; } 569 for ( ®0® ) { sout | "A"; } 570 for ( ®1® ) { sout | "A"; } 571 for ( ®10® ) { sout | "A"; } 572 for ( ®1 ~= 10 ~ 2® ) { sout | "B"; } 573 for ( ®10 -~= 1 ~ -2® ) { sout | "C"; } 574 for ( ®0.5 ~ 5.5® ) { sout | "D"; } 575 for ( ®5.5 -~ 0.5® ) { sout | "E"; } 576 for ( ®i; 10® ) { sout | i; } 577 for ( ®i; 1 ~= 10 ~ 2® ) { sout | i; } 578 for ( ®i; 10 -~= 1 ~ -2® ) { sout | i; } 579 for ( ®i; 0.5 ~ 5.5® ) { sout | i; } 580 for ( ®i; 5.5 -~ 0.5® ) { sout | i; } 581 for ( ®ui; 2u ~= 10u ~ 2u® ) { sout | ui; } 582 for ( ®ui; 10u -~= 2u ~ -2u® ) { sout | ui; } 583 int start = 3, comp = 10, inc = 2; 584 for ( ®i; start ~ comp ~ inc + 1® ) { sout | i; } 585 \end{cfa} 586 & 587 \begin{cfa} 588 sout | endl; 589 sout | endl; 590 sout | endl; 591 sout | endl; 592 sout | endl; 593 sout | endl; 594 sout | endl; 595 sout | endl; 596 sout | endl; 597 sout | endl; 598 sout | endl; 599 sout | endl; 600 sout | endl; 601 sout | endl; 602 sout | endl; 603 sout | endl; 604 sout | endl; 605 606 sout | endl; 607 \end{cfa} 608 & 609 \begin{cfa} 610 empty 611 empty 612 empty 613 614 A 615 A A A A A A A A A A 616 B B B B B 617 C C C C C 618 D D D D D 619 E E E E E 620 0 1 2 3 4 5 6 7 8 9 621 1 3 5 7 9 622 10 8 6 4 2 623 0.5 1.5 2.5 3.5 4.5 624 5.5 4.5 3.5 2.5 1.5 625 2 4 6 8 10 626 10 8 6 4 2 627 628 3 6 9 629 \end{cfa} 630 \end{tabular} 631 \end{cquote} 540 632 541 633 … … 800 892 801 893 894 % for () => for ( ;; ) 895 % for ( 10 - t ) => for ( typeof(10 - t) ? = 0 ; ? < 10 - t; ? += 1 ) // using 0 and 1 896 % for ( i ; 10 - t ) => for ( typeof(10 - t) i = 0 ; i < 10 - t; i += 1 ) // using 0 and 1 897 % for ( T i ; 10 - t ) => for ( T i = 0 ; i < 10 - t; i += 1 ) // using 0 and 1 898 % for ( 3~9 ) => for ( int ? = 3 ; ? < 9; ? += 1 ) // using 1 899 % for ( i ; 3~9 ) => for ( int i = 3 ; i < 9; i += 1 ) // using 1 900 % for ( T i ; 3~9 ) => for ( T i = 3 ; i < 9; i += 1 ) // using 1 901 902 802 903 %\subsection{\texorpdfstring{Labelled \protect\lstinline@continue@ / \protect\lstinline@break@}{Labelled continue / break}} 803 904 \subsection{\texorpdfstring{Labelled \LstKeywordStyle{continue} / \LstKeywordStyle{break} Statement}{Labelled continue / break Statement}} … … 805 906 While C provides ©continue© and ©break© statements for altering control flow, both are restricted to one level of nesting for a particular control structure. 806 907 Unfortunately, this restriction forces programmers to use \Indexc{goto} to achieve the equivalent control-flow for more than one level of nesting. 807 To prevent having to switch to the ©goto©, \CFA extends the \Indexc{continue}\index{continue@ \lstinline@continue@!labelled}\index{labelled!continue@©continue©} and \Indexc{break}\index{break@\lstinline@break@!labelled}\index{labelled!break@©break©} with a target label to support static multi-level exit\index{multi-level exit}\index{static multi-level exit}~\cite{Buhr85}, as in Java.908 To prevent having to switch to the ©goto©, \CFA extends the \Indexc{continue}\index{continue@©continue©!labelled}\index{labelled!continue@©continue©} and \Indexc{break}\index{break@©break©!labelled}\index{labelled!break@©break©} with a target label to support static multi-level exit\index{multi-level exit}\index{static multi-level exit}~\cite{Buhr85}, as in Java. 808 909 For both ©continue© and ©break©, the target label must be directly associated with a ©for©, ©while© or ©do© statement; 809 910 for ©break©, the target label can also be associated with a ©switch©, ©if© or compound (©{}©) statement. … … 890 991 \end{figure} 891 992 892 Both labelled ©continue© and ©break© are a ©goto©\index{goto@ \lstinline@goto@!restricted} restricted in the following ways:993 Both labelled ©continue© and ©break© are a ©goto©\index{goto@©goto©!restricted} restricted in the following ways: 893 994 \begin{itemize} 894 995 \item
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