c - 如何将二进制字符串转换为多项式形式

Question

我有一个 1001 形式的二进制字符串，我想将其转换为 c 中的 x^3+1。这怎么可能？是否有任何内置函数可以实现这一点。

Answer 1

I have a binary string in the form of 1001 and i want to convert it into x^3+1 in c.How it is possible ? Is there is any built-in function for that.

没有内置函数。

#include <stdio.h>
#include <string.h>

int main()
{
    char binary_string[] = "1001";
    int degree = strlen(binary_string) - 1, exponent, terms = 0;
    for (exponent = degree; 0 <= exponent; --exponent)
        if (binary_string[degree-exponent] == '1')
        {
            if (terms++) printf("+");
            switch (exponent)
            {
            case 0:     printf("1");                break;
            case 1:     printf("x");                break;
            default:    printf("x^%d", exponent);   break;
            }
        }
    puts("");
}