将有符号转换为无符号，反之亦然 [英] Converting Signed to Unsigned and vice versa

问题描述

我必须实现两个函数将有符号转换为无符号，反之亦然。我使用c ++ 11和Linux。

I have to implement two functions that convert signed to unsigned and vice versa. I am using c++11 and Linux.

系统是二进制补码，可以接受char，int，long等。接口必须如上所述，试图实现的东西。有更好的方法吗？这些是正确的吗？如何根据位数更改实现？我需要一些建议。

The system is two's complement and can take char, int, long etc.. The interface must be as stated and I have tried to implement something. Are there better ways to do this? Are these correct? How can I change the implementation based on the number of bits? I need some advice.

uint32_t signedToUnsigned(int32_t x, uint8_t bits)
{
    return ( x > 0 ? x:-x);
}

int32_t unsignedToSigned(uint32_t x, uint8_t bits)
{
    if(x <= INT_MAX )
        return static_cast<int>(x);

    if(x >= INT_MIN)
        return static_cast<int>(x - INT_MIN)+ INT_MIN;
    else
    {
        printf("ERROR");
        return x;
    }
}

编辑：

我需要指定位，因为这将与HW一起使用。所以，我可能需要将返回类型的值限制为18bits或4等...

I need to specifiy the bits as this will be used with HW. So, I may need to limit the value in the return type to 18bits or 4 etc...

推荐答案

例如： std :: cout<< unsignedToSigned（signedToUnsigned（-13，0），0）; // prints 13 NOT -13

static_cast code> std :: cout<< static_cast < int32_t>（static_cast< uint32_t>（-13））; // prints -13

static_cast will survive the round trip: std::cout << static_cast< int32_t >( static_cast< uint32_t >( -13 ) ); // prints -13

所以我认为 static_cast 可以用更清晰的规格更新问题。

So I think static_cast is what you want unless you can update the question with a clearer specification.

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