Question

I’m now porting arduino code to stm32(c/c++). Please help me with this function:

constrain(x, a, b)

Returns

x: if x is between a and b

a: if x is less than a

b: if x is greater than b

Example

sensVal = constrain(sensVal, 10, 150);

// limits range of sensor values to between 10 and 150 

Answer 1

Here a template-version, including a complete program to demonstrate the use (you should be able to copy and paste that):

#include <iostream>

template<class T>
const T& constrain(const T& x, const T& a, const T& b) {
    if(x < a) {
        return a;
    }
    else if(b < x) {
        return b;
    }
    else
        return x;
}

int main() {
    int value = 10;
    std::cout << constrain(value, 5, 20) << "\n"      // prints "10"
              << constrain(value, 15, 20) << "\n"     // prints "15"
              << constrain(value, 5, 9) << std::endl; // prints "9"
}

This can be used for any type that has an operator< (this includes all built-in numeric types, such as int and float).