我想用常量值初始化一个 int 数组,所有 2^n 值从 2^0 到 2^31 我想知道下面哪个方法是正确的,如果它给出我想要的结果,如果有初始化它的方法更简单或更短。
static const char two_n[32];
two_n[32] = {1, 2 ,4 ,8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096,
8192, 16384, 32768, 65535, 131070, 262140, 524280, 1048560,
2097152, 4194304, 8388608, 16777216, 33554432, 67108864, 134217728,
268435456, 536870912, 1073741824, 2147483648};
或
static const char *two_n[32];
two_n[32] = {1, 2 ,4 ,8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096,
8192, 16384, 32768, 65535, 131070, 262140, 524280, 1048560,
2097152, 4194304, 8388608, 16777216, 33554432, 67108864, 134217728,
268435456, 536870912, 1073741824, 2147483648};
或
static const int two_n[32];
two_n[32] = {1, 2 ,4 ,8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096,
8192, 16384, 32768, 65535, 131070, 262140, 524280, 1048560,
2097152, 4194304, 8388608, 16777216, 33554432, 67108864, 134217728,
268435456, 536870912, 1073741824, 2147483648};
最佳答案
以上都不是,因为数组的类型和初始值设定项都不正确。使用 uint32_t
或 unsigned long
,因为它们保证至少为 32 位宽并且能够保存 231 的值,这可能超出int
范围:
static const unsigned long two_n[32] = {
1UL << 0, 1UL << 1, 1UL << 2, 1UL << 3,
1UL << 4, 1UL << 5, 1UL << 6, 1UL << 7,
1UL << 8, 1UL << 9, 1UL << 10, 1UL << 11,
1UL << 12, 1UL << 13, 1UL << 14, 1UL << 15,
1UL << 16, 1UL << 17, 1UL << 18, 1UL << 19,
1UL << 20, 1UL << 21, 1UL << 22, 1UL << 23,
1UL << 24, 1UL << 25, 1UL << 26, 1UL << 27,
1UL << 28, 1UL << 29, 1UL << 30, 1UL << 31
};
关于c - 在 C 中声明我的 int 数组,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/40834233/