C ++数组初始化

Question

float minTime[7]={FLT_MAX};
    for(int i=0;i<7;i++)
        cout << "Min: " << minTime[i] << endl;

Why do I get in the following output :

Min: 3.40282e+038
Min: 0
Min: 0
Min: 0
...

Shoudln't all have the same value as the first one? As it is refered here: C++ Notes

Answer 1

Your linked page says "...the unspecified elements are set to zero."

This is correct; as such, only the first element in your array was specified to be FLT_MAX , the rest are initialized to zero. If you want to set them all to the same value you can use a for-loop, or more succinctly:

std::fill_n(minTime, 7, FLT_MAX);

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As a warning, C++ is a hard language. This means lots of people have lots of misinformation, and this is especially easy to find on the internet. You'd be better off learning from a book on our list . (And yes, the ones not on our list are so because they too contain misinformation!)

Answer 2

Shoudln't all have the same value as the first one?

Nopes! When an array is partially initialized the non-initialized array elements are value initialized ( zero-initialized in this case).

C++03 Section 8.5.1/7

If there are fewer initializers in the list than there are members in the aggregate, then each member not explicitly initialized shall be value-initialized (8.5).
[Example:

 struct S { int a; char* b; int c; }; S ss = { 1, "asdf" }; 

initializes ss.a with 1, ss.b with "asdf", and ss.c with the value of an expression of the form int(), that is, 0. ]

Answer 3

不，只有第一个值使用提供的值初始化，其他值按照标准初始化。