多项式输入c语言代码

在C语言中，处理多项式的常见操作包括加法、减法、乘法以及计算值。下面是一个简单的多项式表示结构体的例子，用于存储系数和次数：

#include <stdio.h>

// 定义多项式结构体
typedef struct {
    int degree; // 次数
    double coefficients[100]; // 最高次项系数数组，假设最多有99项
} Polynomial;

// 初始化多项式
void init_polynomial(Polynomial* poly, int n) {
    poly->degree = n - 1;
    for (int i = 0; i <= n; ++i)
        poly->coefficients[i] = 0.0; // 初始化所有系数为0
}

// 添加两个多项式
void add_polynomials(Polynomial* result, const Polynomial& poly1, const Polynomial& poly2) {
    int max_degree = MAX(poly1.degree, poly2.degree);
    for (int i = 0; i <= max_degree; ++i) {
        result->coefficients[i] += poly1.coefficients[i] + poly2.coefficients[i];
    }
    result->degree = max_degree;
}

// 计算多项式值
double evaluate_polynomial(const Polynomial& poly, double x) {
    int n = poly.degree;
    double term = poly.coefficients[n] * pow(x, n);
    double sum = term;
    
    for (n--; n >= 0; --n) {
        term = poly.coefficients[n] * pow(x, n);
        sum += term;
    }
    
    return sum;
}

// 示例：主函数演示多项式操作
int main() {
    Polynomial p1, p2, result;
    init_polynomial(&p1, 2); // p1 = a + bx
    init_polynomial(&p2, 2); // p2 = c + dx
    
    p1.coefficients[0] = 1; // a
    p1.coefficients[1] = 2; // b
    p2.coefficients[0] = 3; // c
    p2.coefficients[1] = 4; // d

    // 打印多项式
    printf("p1(x) = %.2fx^%d + %.2f\n", p1.coefficients[0], p1.degree, p1.coefficients[1]);
    printf("p2(x) = %.2fx^%d + %.2f\n", p2.coefficients[0], p2.degree, p2.coefficients[1]);

    // 添加多项式
    add_polynomials(&result, p1, p2);
    printf("p1(x) + p2(x) = %.2fx^%d + %.2f\n", result.coefficients[0], result.degree, result.coefficients[1]);

    // 计算多项式值
    double x = 5.0;
    printf("p1(%lf) = %.2lf\n", x, evaluate_polynomial(p1, x));
    
    return 0;
}