c++ - 以下类型的声明是否完全有效？

Question

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Answer 1

来自 ISO/IEC 9899:TC3 6.7.8 初始化

26 EXAMPLE 3

The declaration

int y[4][3] = {
{ 1, 3, 5 },
{ 2, 4, 6 },
{ 3, 5, 7 },
};

is a definition with a fully bracketed initialization: 1, 3, and 5 initialize the first row of y (the array object y[0]), namely y[0][0], y[0][1], and y[0][2]. Likewise the next two lines initialize y[1] and y[2]. The initializer ends early, so y[3] is initialized with zeros. Precisely the same effect could have been achieved by

int y[4][3] = {
1, 3, 5, 2, 4, 6, 3, 5, 7
};

The initializer for y[0] does not begin with a left brace, so three items from the list are used. Likewise the next three are taken successively for y[1] and y[2].

所以至少对于 c99 来说它是绝对合法的!