指定初始化数组

Question

的阵列我们大概知道C99 designated initializers，它们可以被用来初始化大常量数组的方式：

const int vals[] = { 
    [0] = 10, 
    [10] = 12 
} 

哪个initalizes的vals指数0到10和vals到12指数10 。

我的问题是如何使用这种风格的指定初始化器阵列的数组。这里是我的示例代码：

typedef enum { 
    COMMON = 0, 
    STRINGS, 
    KEY, 
    PRECUSSIVE, 
    GUITAR, 
    KEYBOARD, 
    BASS, 
    PIANO, 
    DRUMS, 
    _INST_MAX 
} instrument_classification_t; 
    static const int * const instrument_class_hierarchy[] = { 
    [COMMON] = {STRINGS, KEY, PRECUSSIVE, _INST_MAX}, 
    [STRINGS] = {GUITAR, BASS, _INST_MAX}, 
    [KEY] = {PIANO, KEYBOARD, _INST_MAX}, 
    [PRECUSSIVE] = {DRUMS, _INST_MAX}, 
    [GUITAR] = NULL, 
    [KEYBOARD] = NULL, 
    [BASS] = NULL, 
    [PIANO] = NULL, 
    [DRUMS] = NULL 
}; 

但我得到这些警告，这意味着初始化只使用第一个元素。

main.c:166:3: warning: braces around scalar initializer 
    [COMMON] = {STRINGS, KEY, PRECUSSIVE, _INST_MAX}, 
^
main.c:166:3: note: (near initialization for 'instrument_class_hierarchy[0]') 
main.c:166:15: warning: initialization makes pointer from integer without a cast [-Wint-conversion] 
    [COMMON] = {STRINGS, KEY, PRECUSSIVE, _INST_MAX}, 
     ^
main.c:166:15: note: (near initialization for 'instrument_class_hierarchy[0]') 
main.c:166:24: warning: excess elements in scalar initializer 
    [COMMON] = {STRINGS, KEY, PRECUSSIVE, _INST_MAX}, 
        ^
main.c:166:24: note: (near initialization for 'instrument_class_hierarchy[0]') 
main.c:166:29: warning: excess elements in scalar initializer 
    [COMMON] = {STRINGS, KEY, PRECUSSIVE, _INST_MAX}, 
         ^
main.c:166:29: note: (near initialization for 'instrument_class_hierarchy[0]') 
main.c:166:41: warning: excess elements in scalar initializer 
    [COMMON] = {STRINGS, KEY, PRECUSSIVE, _INST_MAX}, 
            ^
main.c:166:41: note: (near initialization for 'instrument_class_hierarchy[0]') 
main.c:167:3: warning: braces around scalar initializer 
    [STRINGS] = {GUITAR, BASS, _INST_MAX}, 
^
main.c:167:3: note: (near initialization for 'instrument_class_hierarchy[1]') 
main.c:167:16: warning: initialization makes pointer from integer without a cast [-Wint-conversion] 
    [STRINGS] = {GUITAR, BASS, _INST_MAX}, 
      ^
main.c:167:16: note: (near initialization for 'instrument_class_hierarchy[1]') 
main.c:167:24: warning: excess elements in scalar initializer 
    [STRINGS] = {GUITAR, BASS, _INST_MAX}, 
        ^
main.c:167:24: note: (near initialization for 'instrument_class_hierarchy[1]') 
main.c:167:30: warning: excess elements in scalar initializer 
    [STRINGS] = {GUITAR, BASS, _INST_MAX}, 
         ^
main.c:167:30: note: (near initialization for 'instrument_class_hierarchy[1]') 
main.c:168:3: warning: braces around scalar initializer 
    [KEY] = {PIANO, KEYBOARD, _INST_MAX}, 
^
main.c:168:3: note: (near initialization for 'instrument_class_hierarchy[2]') 
main.c:168:12: warning: initialization makes pointer from integer without a cast [-Wint-conversion] 
    [KEY] = {PIANO, KEYBOARD, _INST_MAX}, 
     ^
main.c:168:12: note: (near initialization for 'instrument_class_hierarchy[2]') 
main.c:168:19: warning: excess elements in scalar initializer 
    [KEY] = {PIANO, KEYBOARD, _INST_MAX}, 
      ^
main.c:168:19: note: (near initialization for 'instrument_class_hierarchy[2]') 
main.c:168:29: warning: excess elements in scalar initializer 
    [KEY] = {PIANO, KEYBOARD, _INST_MAX}, 
         ^
main.c:168:29: note: (near initialization for 'instrument_class_hierarchy[2]') 
main.c:169:3: warning: braces around scalar initializer 
    [PRECUSSIVE] = {DRUMS, _INST_MAX}, 
^
main.c:169:3: note: (near initialization for 'instrument_class_hierarchy[3]') 
main.c:169:19: warning: initialization makes pointer from integer without a cast [-Wint-conversion] 
    [PRECUSSIVE] = {DRUMS, _INST_MAX}, 
      ^
main.c:169:19: note: (near initialization for 'instrument_class_hierarchy[3]') 
main.c:169:26: warning: excess elements in scalar initializer 
    [PRECUSSIVE] = {DRUMS, _INST_MAX}, 

Answer 1

值的支撑列表无法初始化指针。你的错误是一样的：

int *p = { 1, 2, 3 }; 

你可以使用一个复合文字来代替：

// ... 
[COMMON] = (const int[]){STRINGS, KEY, PRECUSSIVE, _INST_MAX}, 

这是假定该代码是在文件范围内（即在任何函数之外），这意味着复合文字具有静态存储时间，因此指向它们是安全的。如果你的代码实际上在一个函数内，你需要声明单独的静态数组或者做一些其他修改。