[問題] range for with multidimensional arrays
目前正在讀 C++ Primer 5th edition
int ia[3][4] = {{0,1,2,3},{4,5,6,7},{8,9,10,11}};
for(auto row : ia)
for(auto col : row)
cout<< col <<endl;
這樣子compile是不會過的
外層迴圈的row必須要是reference才行，也就是 &row
書上的理由如下:
Because row is not a reference, when the compiler initializes row it will
convert each array element (like any other object of array type) to a pointer
to that array's first element. As a result, in this loop the type of row is
int*, The inner for loop is illegal. Despite our intentions, that loop
attempts to iterate over an int* .
reference不就是讓一個變數有了另一個名稱，並且這兩個名稱都使用同一塊記憶體
位址嗎?
為甚麼有reference的話，each array element就不會被轉換成指向第一個元素的指標?
請問為什麼row要reference呢
謝謝
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※ 編輯: woody3724 (219.85.166.154), 04/20/2017 18:27:41
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喔喔喔!! 我懂了，非常感謝
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