char 数组的 cin 和 cin.get() 之间的区别 [英] Difference between cin and cin.get() for char array

问题描述

我有这两个代码:

char a[256];cin>>a;cout<

和

char a[256];cin.get(a,256);cin.get();cout<

也许，相对于第二个没有 cin.get();

char a[256];cin.get(a,256);cout<

我的问题是(第一个):对于 char 数组，我应该使用什么?cin 还是 cin.get()?我为什么要使用 cin.get();我的 char 初始化后没有参数?

我的第二个问题是:我的 c++ 老师教我每次使用 cin.get() 初始化字符，并在每次初始化 char 数组或 int 数组或只是 int 或其他任何时间后，再次放入 cin.get();在它之后.这就是我最初想问的.

所以，现在我得到了这 2 个:在这种情况下，整数初始化后没有 cin.get() ，我的程序将中断，我不能再做我的 char 初始化.

int n;cin>>n;字符 [256];cin.get(a,256);cin.get();//有或没有 cin.get();?cout<

还有一个正确的:

int n;cin>>n;cin.get();字符 [256];cin.get(a,256);cin.get();//再次，有还是没有?cout<

那么，怎么了?请有人解释每个案例！谢谢.

解决方案

他们做不同的事情，所以选择你想要的，或者下面给出的更好的选择.

第一个 cin>>a; 读取单个单词，跳过任何前导空格字符，并在遇到空格字符(包括行尾)时停止.p>

第二个 cin.get(a,256);cin.get(); 读取一整行，然后使用行尾字符，这样重复此操作将读取下一行.cin.getline(a,256) 是一种稍微简洁的方法.

第三个 cin.get(a,256) 读取一整行，但将行尾字符留在流中，因此重复此操作不会提供更多输入.

在每种情况下，如果输入的单词/行长于固定大小的缓冲区，您都会遇到某种不良行为.因此，您通常应该使用更友好的字符串类型:

std::string a;std::cin >>一个;//一个字std::getline(std::cin, a);//整行

字符串会增长以适应任何数量的输入.

I have these 2 codes:

char a[256];
cin>>a;
cout<<a;

and

char a[256];
cin.get(a,256);cin.get();
cout<<a;

and maybe, relative to the second one without cin.get();

char a[256];
cin.get(a,256);
cout<<a;

My question is (first one) : for a char array, what should i use? cin or cin.get()? And why should i use cin.get(); with no parameter after my char initialisation?

And my second question is: my c++ teacher taught me to use every time cin.get() for initialisation chars and AFTER every initialisation char array or int array or just int or whatever, to again put cin.get(); after it. That's what i wanted to ask initially.

So, now i got these 2: In this case, without cin.get() after the integer initialisation, my program will break and i can't do anymore my char initialisation.

int n;
cin>>n;
char a[256];
cin.get(a,256); cin.get();  // with or without cin.get();?
cout<<a;

And the correct one:

int n;
cin>>n; cin.get();
char a[256];
cin.get(a,256); cin.get(); // again, with or without?
cout<<a;

So, what's the matter? Please someone explain for every case ! Thank you.

解决方案

They do different things, so choose whichever does what you want, or the better alternatives given below.

The first cin>>a; reads a single word, skipping over any leading space characters, and stopping when it encounters a space character (which includes the end of the line).

The second cin.get(a,256);cin.get(); reads a whole line, then consumes the end-of-line character so that repeating this will read the next line. cin.getline(a,256) is a slightly neater way to do this.

The third cin.get(a,256) reads a whole line but leaves the end-of-line character in the stream, so that repeating this will give no more input.

In each case, you'll get some kind of ill behaviour if the input word/line is longer than the fixed-size buffer. For that reason, you should usually use a friendlier string type:

std::string a;
std::cin >> a;              // single word
std::getline(std::cin, a);  // whole line

The string will grow to accommodate any amount of input.

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