不灵活的阵列成员

我错误地将指针索引到单个值（反之亦然）。 Typedef也导致自我记录代码但不提供额外的 编译 - 时间类型安全。 这对灵活阵列成员的限制是否合理？核心语法 和语义更好，因为一个数组不应该索引过去元素（而零大小的数组没有元素）。有没有标准的方法 我可以用不完整的数组 成员维护结构的额外类型安全性，而不必用非零大小的标题填充那些结构？非常感谢， Adam Adam Warner写道： 大家好， 无法在C中返回指向数组类型的指针，因为C没有第一个类数组类型。 当然可以。通常，你不是真的想要，但它是可能的。 typedef char array [10]; array * f（void ）{ / * ... * / } 您也可以在没有typedef的情况下编写它 char（* f（无效））[10] { / * ... * / } 你也可以省去大小。 typedef char array []; array * f（void）{ / * ... * / } 或 char（* f（虚空））[] { / * ... * / } 其余信息似乎之后无关紧要。 2006年7月8日星期六00:32:05 -0700，Harald van D？3k写道： Adam Warner写道： >大家好， 一个人无法返回指针C中的数组类型，因为C没有第一类数组类型。 当然可以。通常，你不是真的想要，但它是可能的。 typedef char array [10]; array * f（void ）{ / * ... * / } 您也可以在没有typedef的情况下编写它 char（* f（无效））[10] { / * ... * / } 你也可以省去大小。 typedef char array []; array * f（void）{ / * ... * / } 或 char（* f（无效））[] { / * ... * / } 优秀！谢谢你的更正。 #include< stdint.h> #include< stdlib.h> typedef uint8_t octet_vector_t []; int main（）{ octet_vector_t * vector = malloc（10）; （* vector）[9] = 42; 返回0; } 如果有，请告诉我'是一种避免每个阵列访问的显式解除引用 语法的方法。 问候， Adam Hi all,One cannot return a pointer to an array type in C because C has no firstclass array types. But one can return a pointer to a struct containing anincomplete array via the illegal but widely supported zero array structhack:#include <stdlib.h>typedef struct byte_vector_t byte_vector_t;struct byte_vector_t {unsigned char byte[0];};int main() {byte_vector_t *byte_vector=malloc(10);byte_vector->byte[9]=42;return 0;}It is frequently stated that flexible array members are a substitute forthe zero array struct hack. Let''s see (by compiling file array.c belowwith GNU C):#include <stdlib.h>typedef struct byte_vector_t byte_vector_t;struct byte_vector_t {unsigned char byte[];};int main() {byte_vector_t *byte_vector=malloc(10);byte_vector->byte[9]=42;return 0;}$ gcc -std=c99 array.carray.c:6: error: flexible array member in otherwise empty structGCC refuses to compile this code because C99 states (6.7.2.1,paragraph 2):A structure or union shall not contain a member with incomplete orfunction type (hence, a structure shall not contain an instance ofitself, but may contain a pointer to an instance of itself), exceptthat the last member of a structure with more than one named member may^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^have incomplete array type; such a structure (and any union containing,possibly recursively, a member that is such a structure) shall not be amember of a structure or an element of an array.This restriction is repeated in paragraph 16.The struct types are intended to serve as self-documenting code and stopme from incorrectly indexing a pointer to a single value (and vice versa).Typedefs also lead to self-documenting code but provide no additionalcompile-time type safety.Is this restriction upon flexible array members sensible? The core syntaxand semantics are better because one should not index past the elements ofan array (and a zero sized array has no elements). Is there a standard wayI can maintain the extra type safety of structs with an incomplete arraymember without having to pad those structs with a non-zero sized header?Many thanks,Adam 解决方案 gcc -std=c99 array.carray.c:6: error: flexible array member in otherwise empty structGCC refuses to compile this code because C99 states (6.7.2.1,paragraph 2):A structure or union shall not contain a member with incomplete orfunction type (hence, a structure shall not contain an instance ofitself, but may contain a pointer to an instance of itself), exceptthat the last member of a structure with more than one named member may^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^have incomplete array type; such a structure (and any union containing,possibly recursively, a member that is such a structure) shall not be amember of a structure or an element of an array.This restriction is repeated in paragraph 16.The struct types are intended to serve as self-documenting code and stopme from incorrectly indexing a pointer to a single value (and vice versa).Typedefs also lead to self-documenting code but provide no additionalcompile-time type safety.Is this restriction upon flexible array members sensible? The core syntaxand semantics are better because one should not index past the elements ofan array (and a zero sized array has no elements). Is there a standard wayI can maintain the extra type safety of structs with an incomplete arraymember without having to pad those structs with a non-zero sized header?Many thanks,AdamAdam Warner wrote:Hi all,One cannot return a pointer to an array type in C because C has no firstclass array types.Sure you can. Typically, you won''t really want to, but it''s possible.typedef char array[10];array *f(void) {/* ... */}You can also write it without a typedef aschar (*f(void))[10] {/* ... */}You can also leave out the size.typedef char array[];array *f(void) {/* ... */}orchar (*f(void))[] {/* ... */}The rest of your message seems irrelevant after that. On Sat, 08 Jul 2006 00:32:05 -0700, Harald van D?3k wrote:Adam Warner wrote:>Hi all,One cannot return a pointer to an array type in C because C has no firstclass array types.Sure you can. Typically, you won''t really want to, but it''s possible.typedef char array[10];array *f(void) { /* ... */}You can also write it without a typedef aschar (*f(void))[10] { /* ... */}You can also leave out the size.typedef char array[];array *f(void) { /* ... */}orchar (*f(void))[] { /* ... */}Excellent! Thank you for the correction.#include <stdint.h>#include <stdlib.h>typedef uint8_t octet_vector_t[];int main() {octet_vector_t *vector=malloc(10);(*vector)[9]=42;return 0;}Please let me known if there''s a way to avoid the explicit dereferencingsyntax for every array access.Regards,Adam 这篇关于不灵活的阵列成员的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！ 上岸，阿里云！