3.5Arrays & 3.6Multidimentional Arrays_c++ reference multidimention array-优快云博客

本文深入探讨了C++中使用数组作为变量初始化时的类型转换规则，特别是当使用`auto`关键字时的差异。文章还介绍了如何通过`c_str()`成员函数解决字符串初始化问题，并强调了在使用多维数组进行循环时，所有但内层数组之外的循环变量必须为引用。

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int (*Parray)[10] = &arr; // Parray points to an array of ten ints
int (&arrRef)[10] = arr; // arrRef refers to an array of ten ints
<pre name="code" class="cpp">int *(&arry)[10] = ptrs; // arry is a reference to an array of ten pointers

When we use a variable to subscript an array, we normally should define thatvariable to have typesize_t.

The size_t type is defined in thecstddefheader.

One such implication is that when we use an array as aninitializer for a variable defined usingauto, the deduced type is apointer, not an array:

int ia[] = {0,1,2,3,4,5,6,7,8,9}; // ia is an array of ten ints
auto ia2(ia); // ia2 is an int* that points to the first element in ia

It is worth noting that this conversion does not happen when we usedecltype. The type returned bydecltype(ia)is array of ten ints:

decltype(ia) ia3 = {0,1,2,3,4,5,6,7,8,9};

<pre name="code" class="cpp">ia3 = p; // error: can't assign an int* to an array ia3[4] = i; // ok: assigns the value of i to an element in ia3

There is, however, astring member functionnamed c_str that we can often use to accomplish what we want:
```
char *str = s; // error: can't initialize a char* from a string 
```
```
const char *str = s.c_str(); // ok
```
If a program needs continuing access to the contents of the array returnedbystr(), the program must copy the array returned byc_str.
To use a multidimensional array in a range for, the loop control variable for all but the innermost array must be references.