c - 编写一个不使用算术运算符将两个数字相乘的程序

Question

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How to add two numbers without using ++ or + or another arithmetic operator.

是否可以编写一个程序(用 C 语言)在不使用任何算术运算符(*、+、-、/、%)的情况下将两个数字相乘。

Answer 1

如果您可以使用按位运算符进行加法，下面的代码片段可能会有所帮助

int xor, and, temp;
and = x & y;
xor = x ^ y; 

while(and != 0 )
{
 and <<= 1; 
 temp = xor ^ and;
 and &= xor; 
 xor = temp; 
}

a 和 b 相乘，加上“a”“b”次

unsigned int mult(unsigned int a,unsigned int b)
{
    unsigned int counter=0;
    unsigned int mult = a;
    if(a == 0 || b == 0)
    {
    return 0;
    }

    //Optimize if any of the number is power of two then
    //Just right shift other with value of this number

    while(counter < b )
    {   
    counter = add(counter,1);
    mult = add(mult,a);
    }
    return mult;
}