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.if o .tl '''C Reference Manual - %'
.if e .tl 'C Reference Manual - %'''
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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Unpublished internal memorandum,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.