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- C struct data types may end with a flexible array member with no specified size: struct vectord { short len; // there must be at least one other data member double arr[]; // the flexible array member must be last // The compiler may reserve extra padding space here, like it can between struct members}; Typically, such structures serve as the header in a larger, variable memory allocation: struct vectord *vector = malloc(...);vector->len = ...;for (int i = 0; i < vector->len; i++) vector->arr[i] = ...; // transparently uses the right type (double) (en)
- 灵活数组类型是C99引入的语言特性。即在struct数据类型的最后一个数据成员，可以为一个未指明长度的数组类型。例如： struct double_vector_st { size_t length; double array[]; // the flexible array member should be last}; sizeof运算符作用于这个struct，返回灵活数组成员的偏移量。在堆上分配这种struct，应该保留灵活数组的空间。如下例： struct double_vector_st *allocate_double_vector(size_t len) { struct double_vector_st *vec = malloc(sizeof *vec + len * sizeof vec->array[0]); if (!vec) { perror("malloc double_vector_st failed"); exit(EXIT_FAILURE); } vec->length = len; for (size_t ix = 0; ix < len; ix++) vec->array[ix] = 0.0; return vec;} C++语言标准尚未支持灵活数组类型。但Visual C++2015支持。 (zh)
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- 3541 (xsd:nonNegativeInteger)
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- C struct data types may end with a flexible array member with no specified size: struct vectord { short len; // there must be at least one other data member double arr[]; // the flexible array member must be last // The compiler may reserve extra padding space here, like it can between struct members}; Typically, such structures serve as the header in a larger, variable memory allocation: struct vectord *vector = malloc(...);vector->len = ...;for (int i = 0; i < vector->len; i++) vector->arr[i] = ...; // transparently uses the right type (double) (en)
- 灵活数组类型是C99引入的语言特性。即在struct数据类型的最后一个数据成员，可以为一个未指明长度的数组类型。例如： struct double_vector_st { size_t length; double array[]; // the flexible array member should be last}; sizeof运算符作用于这个struct，返回灵活数组成员的偏移量。在堆上分配这种struct，应该保留灵活数组的空间。如下例： struct double_vector_st *allocate_double_vector(size_t len) { struct double_vector_st *vec = malloc(sizeof *vec + len * sizeof vec->array[0]); if (!vec) { perror("malloc double_vector_st failed"); exit(EXIT_FAILURE); } vec->length = len; for (size_t ix = 0; ix < len; ix++) vec->array[ix] = 0.0; return vec;} (zh)
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- Flexible array member (en)
- 灵活数组类型 (zh)
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