80 lines
3.7 KiB
Markdown
80 lines
3.7 KiB
Markdown
[dcl.ptr]
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# 9 Declarations [[dcl]](./#dcl)
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## 9.3 Declarators [[dcl.decl]](dcl.decl#dcl.ptr)
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### 9.3.4 Meaning of declarators [[dcl.meaning]](dcl.meaning#dcl.ptr)
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#### 9.3.4.2 Pointers [dcl.ptr]
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[1](#1)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/declarations.tex#L3032)
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In a declarationTD whereD has the form
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* [*attribute-specifier-seq*](dcl.attr.grammar#nt:attribute-specifier-seq "9.13.1 Attribute syntax and semantics [dcl.attr.grammar]")opt [*cv-qualifier-seq*](dcl.decl.general#nt:cv-qualifier-seq "9.3.1 General [dcl.decl.general]")opt D1
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and the type of the contained [*declarator-id*](dcl.decl.general#nt:declarator-id "9.3.1 General [dcl.decl.general]") in the declarationTD1 is â*derived-declarator-type-list*Tâ,
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the type of the [*declarator-id*](dcl.decl.general#nt:declarator-id "9.3.1 General [dcl.decl.general]") inD is â*derived-declarator-type-list* [*cv-qualifier-seq*](dcl.decl.general#nt:cv-qualifier-seq "9.3.1 General [dcl.decl.general]") pointer toTâ[.](#1.sentence-1)
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The[*cv-qualifier*](dcl.decl.general#nt:cv-qualifier "9.3.1 General [dcl.decl.general]")*s* apply to the pointer and not to the object pointed to[.](#1.sentence-2)
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Similarly, the optional [*attribute-specifier-seq*](dcl.attr.grammar#nt:attribute-specifier-seq "9.13.1 Attribute syntax and semantics [dcl.attr.grammar]") ([[dcl.attr.grammar]](dcl.attr.grammar "9.13.1 Attribute syntax and semantics")) appertains to the pointer and not to the object pointed to[.](#1.sentence-3)
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[2](#2)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/declarations.tex#L3058)
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[*Example [1](#example-1)*:
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The declarationsconst int ci = 10, *pc = &ci, *const cpc = pc, **ppc;int i, *p, *const cp = &i; declareci,
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a constant integer;pc,
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a pointer to a constant integer;cpc,
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a constant pointer to a constant integer;ppc,
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a pointer to a pointer to a constant integer;i,
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an integer;p,
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a pointer to integer; andcp,
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a constant pointer to integer[.](#2.sentence-1)
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The value ofci,cpc,
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andcp cannot be changed after initialization[.](#2.sentence-2)
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The value ofpc can be changed, and so can the object pointed to bycp[.](#2.sentence-3)
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Examples of
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some correct operations arei = ci;*cp = ci;
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pc++;
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pc = cpc;
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pc = p;
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ppc = &pc;
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Examples of ill-formed operations areci = 1; // error ci++; // error*pc = 2; // error cp = &ci; // error cpc++; // error p = pc; // error ppc = &p; // error
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Each is unacceptable because it would either change the value of an object declaredconst or allow it to be changed through a cv-unqualified pointer later, for example:*ppc = &ci; // OK, but would make p point to ci because of previous error*p = 5; // clobber ci
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â *end example*]
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[3](#3)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/declarations.tex#L3121)
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See also [[expr.assign]](expr.assign "7.6.19 Assignment and compound assignment operators") and [[dcl.init]](dcl.init "9.5 Initializers")[.](#3.sentence-1)
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[4](#4)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/declarations.tex#L3124)
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[*Note [1](#note-1)*:
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Forming a pointer to reference type is ill-formed; see [[dcl.ref]](dcl.ref "9.3.4.3 References")[.](#4.sentence-1)
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Forming a function pointer type is ill-formed if the function type has[*cv-qualifier*](dcl.decl.general#nt:cv-qualifier "9.3.1 General [dcl.decl.general]")*s* or a [*ref-qualifier*](dcl.decl.general#nt:ref-qualifier "9.3.1 General [dcl.decl.general]");
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see [[dcl.fct]](dcl.fct "9.3.4.6 Functions")[.](#4.sentence-2)
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Since the address of a bit-field ([[class.bit]](class.bit "11.4.10 Bit-fields")) cannot be taken,
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a pointer can never point to a bit-field[.](#4.sentence-3)
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â *end note*]
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