getchar_unlocked（）VS scanf（）VS cin [英] getchar_unlocked( ) VS scanf() VS cin

问题描述

这三种输入函数在编程语言中有什么区别。
他们以不同的方式彼此输入？

1.getchar_unlocked（）

  #define getcx getchar_unlocked 
 
 inline void inp（int& n）
 {
n = 0; 
 int ch = getcx（）; int sign = 1; 
 while（ch <'0'|| ch>'9'）{if（ch ==' - '）sign = -1; ch = getcx（）;} 
 
 while（ch> ='0'&& ch< ='9'）
n =（n < n <1）+ ch-'0'，ch = getcx（）; 
 n = n * sign; 
} 
  

2.scanf（％d，& ; n）

3.cin>> n

在输入整数时最少需要多少时间？

我使用c ++中的头文件，

 ＃include< iostream> 
＃include< vector> 
＃include< set> 
＃include< map> 
＃include< queue> 
＃include< stack> 
＃include< string> 
＃include< algorithm> 
＃include< functional> 
＃include< iomanip> 
＃include< cstdio> 
＃include< cmath> 
＃include< cstring> 
＃include< cstdlib> 
＃include< cassert> 
  

解决方案

需要考虑两点。
$ b

getchar_unlocked 在Windows中已弃用，因为它是除非速度因子太多，否则请尝试避免 getchar_unlocked

。

现在，就速度而言。

  getchar_unlocked> getchar 
  

因为在 getchar_unlocked 这使它不安全。

  getchar> scanf 
  

因为 getchar 输入是char类型，而scanf可以读取c中可用的大多数原始类型。

  scanf> cin（>> operator）
  

因为选中此链接

最后

  getchar_unlocked> getchar> scanf> cin 
  

What is the difference among these three input functions in programming language. Do they input in different ways from each other?

1.getchar_unlocked()

 #define getcx getchar_unlocked

 inline void inp( int &n ) 
 {
    n=0;
    int ch=getcx();int sign=1;
    while( ch < '0' || ch > '9' ){if(ch=='-')sign=-1; ch=getcx();}

    while(  ch >= '0' && ch <= '9' )
            n = (n<<3)+(n<<1) + ch-'0', ch=getcx();
    n=n*sign;
  }   

2.scanf("%d",&n)

3.cin>>n

Which one takes least time when input the integers?

I use THese header files in c++ where all 3 cased run in c++;

  #include<iostream>
  #include<vector>
  #include<set>
  #include<map>
  #include<queue>
  #include<stack>
  #include<string>
  #include<algorithm>
  #include<functional>
  #include<iomanip>
  #include<cstdio>
  #include<cmath>
  #include<cstring>
  #include<cstdlib>
  #include<cassert>

解决方案

Two points to consider.

1. getchar_unlocked is deprecated in Windows because it is thread unsafe version of getchar().

2. Unless speed factor is too much necessary, try to avoid getchar_unlocked.

Now, as far as speed is concerned.

    getchar_unlocked > getchar

because there is no input stream lock check in getchar_unlocked which makes it unsafe.

    getchar > scanf

because getchar reads a single character of input which is char type whereas scanf can read most of the primitive types available in c.

    scanf > cin (>> operator)

because check this link

So, finally

getchar_unlocked > getchar > scanf > cin

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