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.pn 26 .fp 3 G 'tr ^\| 'hc $ 'tr @ 'll 6.5i 'ps 10 .ds op \s6\d\fIopt\fP\u\s10 .ds * \fR\v'.2'*\fP\v'-.2' .ds ~ \v'.5'\s14~\s10\v'-.5' 'vs 11p .de pg .sp .4 .ti 1 .. .de et .sp .2 .ft R .ti 1 .. .de dp .sp .7 .ne \\$1 .ft I .nf .. .de ed .fi .br .ft R .. .de ul .sp 1.5 .ne 4 .ft G .. .de ms .sp 1 .ne 4 .. .de fo 'bp .. .de he .po 0 .tl '-''' .po 'sp 0.5i .ft I .if o .tl '''C Reference Manual - %' .if e .tl 'C Reference Manual - %''' .ft 'sp 0.4i .. .de bG .br .fp 3 G .ft G .. .de eG .br .ft R .. .de it .ft I \\$1 .ft R .. .de bd .ft G \\$1 .ft R .. .de se .br .ft I .. .wh 0 he .wh -1i fo .sp 2 .ce REFERENCES .sp 1.5 .ta 2 .tc @ .in 2 .ti 0 1. Johnson, S. C., and Kernighan, B. W. ``The Programming Language B.'' Comp. Sci. Tech. Rep. #8., Bell Laboratories, 1972. .sp .6 .ti 0 2. Ritchie, D. M., and Thompson, K. L. ``The \s8UNIX\s10 Time-sharing System.'' C. ACM \fG7, \fR17, July, 1974, pp. 365-375. .sp .6 .ti 0 3. Peterson, T. G., and Lesk, M. E. ``A User's Guide to the C Language on the IBM 370.'' Internal Memorandum, Bell Laboratories, 1974. .sp .6 .ti 0 4. Thompson, K. L., and Ritchie, D. M. .ft I \s8UNIX\s10 Programmer's Manual. .ft R Bell Laboratories, 1973. .sp .7 .ti 0 5. Lesk, M. E., and Barres, B. A. ``The \s8GCOS\s10 C Library.'' Internal memorandum, Bell Laboratories, 1974. .sp .7 .to 0 .ti 0 6. Kernighan, B. W. ``Programming in C\(mi A Tutorial.'' Unpublished internal memorandum, Bell Laboratories, 1974. .in 0 .bp .sp 1.5 .ce 2 APPENDIX 1 .sp .3 Syntax Summary .sp 1.5 .ta .5i 1i 1.5i 2i 2.5i .in 3 1. Expressions. .sp 1 .dp 4 expression: primary \**\fI expression \fG&\fI expression \fG\(mi\fI expression \fG!\fI expression \*~ expression \fR++\fI lvalue \fR\(mi\(mi\fI lvalue lvalue \fR++\fI lvalue \fR\(mi\(mi\fI \fGsizeof \fIexpression expression binop expression expression \fG?\fI expression \fG:\fI expression lvalue asgnop expression expression \fG,\fI expression .ed .dp 6 primary: identifier constant string \fG( \fIexpression \fG)\fI \fIprimary \fG( \fIexpression-list\*(op \fG)\fI primary \fG[\fI expression \fG]\fI lvalue \fG. \fIidentifier primary \fG\(em> \fIidentifier .ed .dp 2 lvalue: identifier primary \fG[ \fIexpression \fG]\fI lvalue \fG. \fIidentifier primary \fG\(em>\fI identifier \** \fI expression \fG( \fIlvalue \fG)\fR .ed .fi .sp .7 The primary-expression operators .dp .ft G (^) [^] . \(em> .sp .5 .ed have highest priority and group left-to-right. The unary operators .dp .ft G \* & \(mi ! \*~ \fR++ \(mi\(mi \fGsizeof .ed .sp .5 have priority below the primary operators but higher than any binary operator, and group right-to-left. Binary operators and the conditional operator all group left-to-right, and have priority decreasing as indicated: .dp .ft I binop: .ft G \** / % + \(mi >> << < > <= >= == != & .tr ^^ ^ .tr ^\| \(or && \(or\(or ? : .tr ^^ .sp .4 .fi .ft R Assignment operators all have the same priority, and all group right-to-left. .dp 3 .ft I asgnop: .ft G = =+ =\(mi =\** =/ =% =>> =<< =& =^ =\(or .ed .tr ^\| .sp .4 .ft R The comma operator has the lowest priority, and groups left-to-right. .sp .7 2. Declarations. .dp 2 declaration: decl-specifiers declarator-list\*(op \fG; .ed .dp 5 decl-specifiers: type-specifier sc-specifier type-specifier sc-specifier sc-specifier type-specifier .ed .dp 4 sc-specifier: .ft G auto static extern register .ed .dp 6 type-specifier: \fGint \fGchar \fGfloat \fGdouble struct { \fItype-decl-list }\fG struct \fIidentifier { type-decl-list }\fG struct \fIidentifier\fG .ed .dp 2 declarator-list: declarator declarator \fG,\fI declarator-list .ed .dp 6 declarator: identifier \** \fIdeclarator declarator \fG( )\fI declarator \fG[\fI constant-expression\*(op \fG]\fI \fG( \fIdeclarator \fG) .ed .dp 2 type-decl-list: type-declaration type-declaration type-decl-list .ed .dp 2 type-declaration: type-specifier declarator-list \fG; .ed .sp 1.5 3. Statements. .dp 1 statement: expression \fG; .se { \fIstatement-list } .se \fGif ( \fIexpression \fG) \fIstatement .se \fGif ( \fI expression \fG) \fIstatement \fGelse \fIstatement .se \fGwhile ( \fIexpression \fG) \fIstatement .se \fGfor ( \fIexpression\*(op \fG; \fIexpression\*(op \fG; \fIexpression\*(op \fG) statement .se \fGswitch ( \fIexpression \fG) \fIstatement .se \fGcase \fIconstant-expression \fG:\fI statement .se \fGdefault : \fIstatement .se \fGbreak ; .se \fGcontinue ; .se .ft G return ; .se .ft G return ( \fIexpression \fG) ; .se .ft G goto \fIexpression \fG; .se \fIidentifier \fG: \fIstatement .se \fG; .ed .dp 2 statement-list: statement statement statement-list .sp 1.5 .ft R 4. External definitions. .dp 2 program: external-definition external-definition program .dp 2 external-definition: function-definition data-definition .ed .dp 2 function-definition: type-specifier\*(op \fIfunction-declarator function-body .ed .dp 2 function-declarator: declarator \fG( \fI parameter-list\*(op \fG) .ed .dp 1 parameter-list: identifier identifier \fG,\fI parameter-list .ed .dp 1 function-body: type-decl-list function-statement .ed .dp 2 function-statement: { declaration-list\*(op statement-list } .ed .dp 2 data-definition: \fGextern\fI\*(op type-specifier\*(op init-declarator-list\*(op \fG; .ed .dp 2 init-declarator-list: init-declarator init-declarator \fG,\fI init-declarator-list .ed .dp 2 init-declarator: declarator initializer\*(op .ed .dp 5 initializer: constant { constant-expression-list } .ed .dp 5 constant-expression-list: constant-expression constant-expression \fG,\fI constant-expression-list .ed .dp 2 constant-expression: expression .ed .sp .4 5. Preprocessor .dp 1 \fG# define \fIidentifier token-string .ed .dp 1 \fG# include "\fIfilename^\fG" .ed .in 0 .bp .ds s \\s8 .ds n \\s10 .ft R .fi .sp 1 .ce 2 APPENDIX 2 Implementation Peculiarities .sp 2 This Appendix briefly summarizes the differences between the implementations of C on the \*sPDP\*n-11 under \*sUNIX\*n and on the \*sHIS\*n 6070 under \*sGCOS\*n; it includes some known bugs in each implementation. Each entry is keyed by an indicator as follows: .sp .ta .4i .8i .nf h hard to fix g \*sGCOS\*n version should probably be changed u \*sUNIX\*n version should probably be changed d Inherent difference likely to remain .sp .fi This list was prepared by M. E. Lesk, S. C. Johnson, E. N. Pinson, and the author. .sp 2 .fi .ta .4i 1.2i .in 1.2i .ti0 .ft I A. Bugs or differences from C language specifications .ft R .sp .ti0 hg A.1) \*sGCOS\*n does not do type conversions in ``?:''. .ti0 hg A.2) \*sGCOS\*n has a bug in \fGint\fR and \fGreal\fR comparisons; the numbers are compared by subtraction, and the difference must not overflow. .ti 0 g A.3) When \fIx\fR is a \fGfloat\fR, the construction ``test ? \(mix : x'' is illegal on \*sGCOS\*n. .ti0 hg A.4) ``p1\(mi>p2 =+ 2'' causes a compiler error, where p1 and p2 are pointers. .ti0 u A.5) On \*sUNIX\*n, the expression in a \fGreturn\fR statement is \fInot\fR converted to the type of the function, as promised. .ti0 hug A.6) \fGentry\fR statement is not implemented at all. .sp .ne 5 .ft I .ti0 .ft I B. Implementation differences .ft R .sp .ti0 d B.1) Sizes of character constants differ; \*sUNIX\*n: 2, \*sGCOS\*n: 4. .ti0 d B.2) Table sizes in compilers differ. .ti0 d B.3) \fGchar\fRs and \fGint\fRs have different sizes; \fGchar\fRs are 8 bits on \*sUNIX\*n, 9 on \*sGCOS\*n; words are 16 bits on \*sUNIX\*n and 36 on \*sGCOS\*n. There are corresponding differences in representations of \fGfloat\fRs and \fGdouble\fRs. .ti0 d B.4) Character arrays stored left to right in a word in \*sGCOS\*n, right to left in \*sUNIX\*n. .ti0 g B.5) Passing of floats and doubles differs; \*sUNIX\*n passes on stack, \*sGCOS\*n passes pointer (hidden to normal user). .ti0 g B.6) Structures and strings are aligned on a word boundary in \*sUNIX\*n, not aligned in \*sGCOS\*n. .ti0 g B.7) \*sGCOS\*n preprocessor supports #rename, #escape; \*sUNIX\*n has only #define, #include. .ti0 u B.8) Preprocessor is not invoked on \*sUNIX\*n unless first character of file is ``#''. .ti0 u B.9) The external definition ``static int .^.^.'' is legal on \*sGCOS\*n, but gets a diagnostic on \*sUNIX\*n. (On \*sGCOS\*n it means an identifier global to the routines in the file but invisible to routines compiled separately.) .ti 0 g B.10) A compound statement on \*sGCOS\*n must contain one ``;'' but on \*sUNIX\*n may be empty. .ti 0 g B.11) On \*sGCOS\*n case distinctions in identifiers and keywords are ignored; on \*sUNIX\*n case is significant everywhere, with keywords in lower case. .sp .ne 5 .ti0 .ft I C. Syntax Differences .ft R .sp .ti0 g C.1) \*sUNIX\*n allows broader classes of initialization; on \*sGCOS\*n an initializer must be a constant, name, or string. Similarly, \*sGCOS\*n is much stickier about wanting braces around initializers and in particular they must be present for array initialization. .ti0 g C.2) ``int extern'' illegal on \*sGCOS\*n; must have ``extern int'' (storage class before type). .ti0 g C.3) Externals on \*sGCOS\*n must have a type (not defaulted to \fGint\fR). .ti0 u C.4) \*sGCOS\*n allows initialization of internal \fGstatic\fR (same syntax as for external definitions). .ti0 g C.5) integer\(mi>... is not allowed on \*sGCOS\*n. .ti0 g C.6) Some operators on pointers are illegal on \*sGCOS\*n (<, >). .ti0 g C.7) \fGregister\fR storage class means something on \*sUNIX\*n, but is not accepted on \*sGCOS\*n. .ti0 g C.8) Scope holes: ``int x; f^(^^)^{int x;}'' is illegal on \*sUNIX\*n but defines two variables on \*sGCOS\*n. .ti0 g C.9) When function names are used as arguments on \*sUNIX\*n, either ``fname'' or ``&fname'' may be used to get a pointer to the function; on \*sGCOS\*n ``&fname'' generates a doubly-indirect pointer. (Note that both are wrong since the ``&'' is supposed to be supplied for free.) .sp .ne 5 .ti0 .ft I D. Operating System Dependencies .sp .ft R .ti0 d D.1) \*sGCOS\*n allocates external scalars by SYMREF; \*sUNIX\*n allocates external scalars as labelled common; as a result there may be many uninitialized external definitions of the same variable on \*sUNIX\*n but only one on \*sGCOS\*n. .ti0 d D.2) External names differ in allowable length and character set; on \*sUNIX\*n, 7 characters and both cases; on \*sGCOS\*n 6 characters and only one case. .sp .ne 5 .ft I .ti0 E. Semantic Differences .ft R .sp .ti0 hg E.1) ``int i, *p; p=i; i=p;'' does nothing on \*sUNIX\*n, does something on \*sGCOS\*n (destroys right half of i) . .ti0 d E.2) ``>>'' means arithmetic shift on \*sUNIX\*n, logical on \*sGCOS\*n. .ti0 d E.3) When a \fGchar\fR is converted to integer, the result is always positive on \*sGCOS\*n but can be negative on \*sUNIX\*n. .ti0 d E.4) Arguments of subroutines are evaluated left-to-right on \*sGCOS\*n, right-to-left on \*sUNIX\*n.