c++尝试初始化二维数组中的值

Question

我已经创建了一个名为 digits 的二维数组，并且想一个一个地初始化每个子数组以使我的代码更清晰。我了解以下代码有效:

string digits[2][5] = { { " - ","| |","   ","| |"," - " },{ " - ","| |","   ","| |"," - " } };

但我想知道为什么以下内容不起作用:

string digits[2][5];
digits[0] = { " - ","| |","   ","| |"," - " };
digits[1] = { " - ", "| |", "   ", "| |", " - " };

Answer 1

第二个不是初始化，而是赋值(digits 的元素)。

string digits[2][5];                               // initialization
digits[0] = { " - ","| |","   ","| |"," - " };     // assignment of the 1st element of digits
digits[1] = { " - ", "| |", "   ", "| |", " - " }; // assignment of the 2nd element of digits

digits 的元素是一个数组，原始 array不能整体赋值。

Objects of array type cannot be modified as a whole: even though they are lvalues (e.g. an address of array can be taken), they cannot appear on the left hand side of an assignment operator

您可以使用 std::array 或 std::vector 来执行此操作，它们可以使用花括号初始化器进行赋值。

std::array<std::array<std::string, 5>, 2> digits;
digits[0] = { " - ","| |","   ","| |"," - " };
digits[1] = { " - ", "| |", "   ", "| |", " - " };