STD：：在C++ 17中钳位-yiteyi-C++库

将变量钳制到给定范围[高–低]。

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If num > high, num is assigned high.
If num < low, num is assigned low.
If num is already clamped, no modifications.

注：从C++17开始，该函数在header中定义。

例如：

Input : num = 100, Range : 10 - 90
Output : num = 90

Input : num = 5, Range : 10 - 90
Output : num = 10

Input : num = 50, Range : 10 - 90
Output : num = 50

语法：

templateconstexpr const T& clamp( const T& num, const T& low, const T& high );
template
constexpr const T& clamp( const T& v, const T& lo, const T& hi, Compare comp );
Parameters
num      -    the value to clamp
low, high  -    the boundaries to clamp num to
comp      -    comparison function object which returns ?true if low is less than num
                and num is less than high. 

Return value
Reference to low if num is less than low,
Reference to high if high is less than num,
otherwise reference to num.

Applications :
To keep a list of inputs specified to a given range. 
Preventing size overflow.

                     // CPP program to illustrate                   
                     // std::clamp                   
                     #include <bits/stdc++.h>                   
                             
                     // Driver code                   
                     int                               main()                   
                     {                   
                                         // range [10 - 100]                   
                                         int                               high = 100, low = 10;                   
                             
                                         // num1 higher than range                   
                                         int                               num1 = 120;                   
                             
                                         // num2 lower than range                   
                                         int                               num2 = 5;                   
                             
                                         // num3 in range                   
                                         int                               num3 = 50;                   
                             
                                         // clamping all variables                   
                                         num1 = std::clamp(num1, low, high);                   
                                         num2 = std::clamp(num2, low, high);                   
                                         num3 = std::clamp(num3, low, high);                   
                             
                                         // printing result                   
                                         std::cout << num1 <<                               " "                               << num2 <<                               " "                               << num3;                   
                     }                   

输出：

100 10 50

                     // CPP program to illustrate clamping                   
                     // array elements in given range                   
                     #include <iostream>                   
                     #include <algorithm>                   
                             
                     // Range [30 - 60]                   
                     int                               low = 30, high = 60;                   
                             
                     // Function to clamp the elements in given range                   
                     void                               clamp_arr_in_range(                               int                               arr[],                               int                               n)                   
                     {                   
                                         // Clamping the array elements                   
                                         for                               (                               int                               i = 0; i < n; i++) {                   
                                         arr[i] = std::clamp(arr[i], low, high);                   
                                         }                   
                     }                   
                             
                     // Driver code                   
                     int                               main()                   
                     {                   
                                         // Array having elements to be clamped                   
                                         int                               arr[] = { 10, 20, 30, 40, 50, 60, 70, 80 };                   
                             
                                         // Size of array                   
                                         int                               n =                               sizeof                               (arr) /                               sizeof                               (arr[0]);                   
                             
                                         // Function call to clamp the elements                   
                                         clamp_arr_in_range(arr, n);                   
                             
                                         // Printing the array                   
                                         for                               (                               int                               i = 0; i < n; i++)                   
                                         std::cout << arr[i] <<                               " "                               ;                   
                     }                   

输出：

30 30 30 40 50 60 60 60

带二元谓词

                     // C++ program to implement std::clamp                   
                     // with Binary Predicate                   
                             
                     #include <bits/stdc++.h>                   
                             
                     // Binary predicate                   
                     bool                               comp(                               int                               a,                               int                               b)                   
                     {                   
                                         return                               (a < b);                   
                     }                   
                             
                     // Driver code                   
                     int                               main()                   
                     {                   
                                         // range [10 - 100]                   
                                         int                               high = 100, low = 10;                   
                             
                                         // num1 higher than range                   
                                         int                               num1 = 120;                   
                             
                                         // num2 lower than range                   
                                         int                               num2 = 5;                   
                             
                                         // num3 in range                   
                                         int                               num3 = 50;                   
                             
                                         // clamping all variables                   
                                         num1 = std::clamp(num1, low, high, comp);                   
                                         num2 = std::clamp(num2, low, high, comp);                   
                                         num3 = std::clamp(num3, low, high, comp);                   
                             
                                         // printing result                   
                                         std::cout << num1 <<                               " "                               << num2 <<                               " "                               << num3;                   
                     }                   

输出：

100 10 50

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