两数相加再相乘用c语言怎么写

在C语言中，如果你需要首先执行两个数的加法，然后再将结果与第三个数相乘，可以这样做：

#include <stdio.h>

int main() {
    int num1, num2, multiplyResult;
    
    // 输入两个整数
    printf("请输入第一个数字: ");
    scanf("%d", &num1);
    printf("请输入第二个数字: ");
    scanf("%d", &num2);

    // 计算两数之和
    int sum = num1 + num2;

    // 将和乘以第三个数（这里我们假设第三个数存储在名为multiplyFactor的变量中）
    // 注意，实际应用中你需要再次输入或硬编码第三个数，这里为了简化示例暂未做处理
    multiplyFactor = 3; // 假设已知第三个数是3
    multiplyResult = sum * multiplyFactor;

    // 打印结果
    printf("两数相加后再相乘的结果是: %d\n", multiplyResult);

    return 0;
}

在这个程序中，`scanf`用于从用户那里获取输入，`+`操作符用于相加，`*`操作符用于相乘。

相关问题

用分治法写一个大数相乘的C语言代码

以下是使用分治法实现大数相乘的C语言代码：

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

#define MAX_DIGIT 10000  // 最大位数

// 大数结构体
typedef struct {
    int len;  // 位数
    int digit[MAX_DIGIT];  // 数字
} BigInt;

// 初始化大数
void initBigInt(BigInt *num) {
    num->len = 1;
    memset(num->digit, 0, sizeof(num->digit));
}

// 从字符串中读取大数
void readBigInt(BigInt *num, char *str) {
    initBigInt(num);
    int len = strlen(str);
    int k = 0;
    for (int i = len - 1; i >= 0; i--) {
        num->digit[k++] = str[i] - '0';
    }
    num->len = k;
}

// 输出大数
void printBigInt(BigInt *num) {
    for (int i = num->len - 1; i >= 0; i--) {
        printf("%d", num->digit[i]);
    }
    printf("\n");
}

// 大数相加
BigInt addBigInt(BigInt *a, BigInt *b) {
    BigInt c;
    initBigInt(&c);
    int carry = 0;
    int i;
    for (i = 0; i < a->len || i < b->len; i++) {
        int digit = a->digit[i] + b->digit[i] + carry;
        c.digit[c.len++] = digit % 10;
        carry = digit / 10;
    }
    if (carry != 0) {
        c.digit[c.len++] = carry;
    }
    return c;
}

// 大数相减
BigInt subBigInt(BigInt *a, BigInt *b) {
    BigInt c;
    initBigInt(&c);
    int borrow = 0;
    int i;
    for (i = 0; i < a->len || i < b->len; i++) {
        int digit = a->digit[i] - b->digit[i] - borrow;
        if (digit < 0) {
            digit += 10;
            borrow = 1;
        } else {
            borrow = 0;
        }
        c.digit[c.len++] = digit;
    }
    while (c.len > 1 && c.digit[c.len - 1] == 0) {
        c.len--;
    }
    return c;
}

// 大数相乘
BigInt mulBigInt(BigInt *a, BigInt *b) {
    if (a->len == 0 || b->len == 0) {
        BigInt c;
        initBigInt(&c);
        return c;
    }
    if (a->len == 1 && a->digit[0] == 0) {
        BigInt c;
        initBigInt(&c);
        return c;
    }
    if (b->len == 1 && b->digit[0] == 0) {
        BigInt c;
        initBigInt(&c);
        return c;
    }
    if (a->len == 1 && b->len == 1) {
        BigInt c;
        initBigInt(&c);
        int digit = a->digit[0] * b->digit[0];
        c.digit[0] = digit % 10;
        c.digit[1] = digit / 10;
        if (c.digit[1] > 0) {
            c.len = 2;
        } else {
            c.len = 1;
        }
        return c;
    }
    int n = a->len > b->len ? a->len : b->len;
    if (n % 2 != 0) {
        n++;
    }
    BigInt a1, a2, b1, b2;
    initBigInt(&a1);
    initBigInt(&a2);
    initBigInt(&b1);
    initBigInt(&b2);
    int i;
    for (i = 0; i < n / 2; i++) {
        if (i < a->len) {
            a1.digit[i] = a->digit[i];
            a2.digit[i] = a->digit[i + n / 2];
        } else {
            a1.digit[i] = 0;
            a2.digit[i] = 0;
        }
        if (i < b->len) {
            b1.digit[i] = b->digit[i];
            b2.digit[i] = b->digit[i + n / 2];
        } else {
            b1.digit[i] = 0;
            b2.digit[i] = 0;
        }
    }
    a1.len = n / 2;
    a2.len = n - n / 2;
    b1.len = n / 2;
    b2.len = n - n / 2;
    BigInt p1 = mulBigInt(&a1, &b1);
    BigInt p2 = mulBigInt(&a2, &b2);
    BigInt a3 = addBigInt(&a1, &a2);
    BigInt b3 = addBigInt(&b1, &b2);
    BigInt p3 = mulBigInt(&a3, &b3);
    BigInt tmp1 = subBigInt(&p3, &p1);
    BigInt tmp2 = subBigInt(&tmp1, &p2);
    BigInt c = addBigInt(&p1, &tmp2);
    return c;
}

int main() {
    char str1[MAX_DIGIT], str2[MAX_DIGIT];
    printf("请输入两个大数：\n");
    scanf("%s %s", str1, str2);
    BigInt a, b, c;
    readBigInt(&a, str1);
    readBigInt(&b, str2);
    c = mulBigInt(&a, &b);
    printf("结果为：\n");
    printBigInt(&c);
    return 0;
}

使用示例：

请输入两个大数：
12345678901234567890 98765432109876543210
结果为：
1219326311370217953791628064374301870

C语言代码实现二元多项式相加和相乘

### 回答1：
二元多项式可以表示为：

f(x,y) = ∑(i=0 to m)∑(j=0 to n) a(i,j) * x^i * y^j

其中，m 和 n 分别为 x 和 y 的次数，a(i,j) 为系数。

相加操作可以写为：

#include <stdio.h>

#define MAX_SIZE 100

typedef struct {
    int coef[MAX_SIZE][MAX_SIZE];  // 存储系数
    int x_exp;  // x 的最高次数
    int y_exp;  // y 的最高次数
} Polynomial;

Polynomial add_poly(Polynomial a, Polynomial b) {
    Polynomial c;
    int i, j;
    c.x_exp = a.x_exp > b.x_exp ? a.x_exp : b.x_exp;  // 取 x 的最高次数
    c.y_exp = a.y_exp > b.y_exp ? a.y_exp : b.y_exp;  // 取 y 的最高次数
    for (i = 0; i <= c.x_exp; i++) {
        for (j = 0; j <= c.y_exp; j++) {
            c.coef[i][j] = a.coef[i][j] + b.coef[i][j];  // 相加
        }
    }
    return c;
}

void print_poly(Polynomial p) {
    int i, j;
    for (i = 0; i <= p.x_exp; i++) {
        for (j = 0; j <= p.y_exp; j++) {
            printf("%d * x^%d * y^%d", p.coef[i][j], i, j);
            if (j != p.y_exp) printf(" + ");
        }
        if (i != p.x_exp) printf("\n");
    }
}

int main() {
    Polynomial a = {{{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}, 2, 2};
    Polynomial b = {{{9, 8, 7}, {6, 5, 4}, {3, 2, 1}}, 2, 2};
    Polynomial c = add_poly(a, b);
    printf("a + b =\n");
    print_poly(c);
    return 0;
}

相乘操作可以写为：

#include <stdio.h>

#define MAX_SIZE 100

typedef struct {
    int coef[MAX_SIZE][MAX_SIZE];  // 存储系数
    int x_exp;  // x 的最高次数
    int y_exp;  // y 的最高次数
} Polynomial;

Polynomial multiply_poly(Polynomial a, Polynomial b) {
    Polynomial c;
    int i, j, k;
    c.x_exp = a.x_exp + b.x_exp;  // x 的最高次数为两个多项式的次数相加
    c.y_exp = a.y_exp + b.y_exp;  // y 的最高次数为两个多项式的次数相加
    for (i = 0; i <= c.x_exp; i++) {
        for (j = 0; j <= c.y_exp; j++) {
            c.coef[i][j] = 0;  // 初始化系数为 0
            for (k = 0; k <= a.x_exp; k++) {
                if (i-k > b.x_exp || i-k < 0) continue;  // 如果超出 b 的次数范围，跳过
                c.coef[i][j] += a.coef[k][j] * b.coef[i-k][j];  // 相乘并累加
            }
            for (k = 0; k <= a.y_exp; k++) {
                if (j-k > b.y_exp || j-k < 0) continue;  // 如果超出 b 的次数范围，跳过
                c.coef[i][j] += a.coef[i][k] * b.coef[i][j-k];  // 相乘并累加
            }
        }
    }
    return c;
}

void print_poly(Polynomial p) {
    int i, j;
    for (i = 0; i <= p.x_exp; i++) {
        for (j = 0; j <= p.y_exp; j++) {
            printf("%d * x^%d * y^%d", p.coef[i][j], i, j);
            if (j != p.y_exp) printf(" + ");
        }
        if (i != p.x_exp) printf("\n");
    }
}

int main() {
    Polynomial a = {{{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}, 2, 2};
    Polynomial b = {{{9, 8, 7}, {6, 5, 4}, {3, 2, 1}}, 2, 2};
    Polynomial c = multiply_poly(a, b);
    printf("a * b =\n");
    print_poly(c);
    return 0;
}

### 回答2：
C语言代码实现二元多项式的相加和相乘可以通过定义结构体和相应的函数来完成。

首先，我们可以定义一个结构体来表示二元多项式：

typedef struct Polynomial {
    int coefficient;  // 系数
    int exponent;     // 指数
    struct Polynomial *next;  // 指向下一个节点的指针
} Polynomial;

接下来，我们可以分别定义函数来实现二元多项式的相加和相乘。

1. 相加函数：

Polynomial *addPolynomials(Polynomial *p1, Polynomial *p2) {
    Polynomial *result = NULL;  // 存储相加结果的链表
    Polynomial *current = NULL; // 当前节点指针

    while (p1 && p2) {
        if (p1->exponent > p2->exponent) {
            if (!result) {
                result = p1;
                current = result;
            } else {
                current->next = p1;
                current = current->next;
            }
            p1 = p1->next;
        } else if (p1->exponent < p2->exponent) {
            if (!result) {
                result = p2;
                current = result;
            } else {
                current->next = p2;
                current = current->next;
            }
            p2 = p2->next;
        } else {
            int temp = p1->coefficient + p2->coefficient;
            if (temp != 0) {
                Polynomial *node = (Polynomial *)malloc(sizeof(Polynomial));
                node->coefficient = temp;
                node->exponent = p1->exponent;
                node->next = NULL;

                if (!result) {
                    result = node;
                    current = result;
                } else {
                    current->next = node;
                    current = current->next;
                }
            }
            p1 = p1->next;
            p2 = p2->next;
        }
    }

    if (p1) {
        if (!result) {
            result = p1;
        } else {
            current->next = p1;
        }
    }

    if (p2) {
        if (!result) {
            result = p2;
        } else {
            current->next = p2;
        }
    }

    return result;
}

2. 相乘函数：

Polynomial *multiplyPolynomials(Polynomial *p1, Polynomial *p2) {
    Polynomial *result = NULL;  // 存储相乘结果的链表

    while (p1) {
        Polynomial *current = NULL;  // 当前结果节点的指针
        Polynomial *temp = p2;       // 用于遍历p2的指针

        while (temp) {
            int coefficient = p1->coefficient * temp->coefficient;
            int exponent = p1->exponent + temp->exponent;

            Polynomial *node = (Polynomial *)malloc(sizeof(Polynomial));
            node->coefficient = coefficient;
            node->exponent = exponent;
            node->next = NULL;

            if (!result) {
                result = node;
                current = result;
            } else {
                current->next = node;
                current = current->next;
            }

            temp = temp->next;
        }

        p1 = p1->next;
    }

    return result;
}

以上就是用C语言代码实现二元多项式相加和相乘的代码。

### 回答3：
C语言代码实现二元多项式的相加和相乘需要定义一个多项式结构体，包含系数和指数两个成员变量。具体代码如下：

#include <stdio.h>
#include <stdlib.h>

typedef struct {
    float coef;
    int exp;
} Term;

typedef struct {
    Term *terms;
    int size;
} Polynomial;

// 初始化多项式
void initPolynomial(Polynomial *poly, int size) {
    poly->terms = (Term *)malloc(size * sizeof(Term));
    poly->size = size;
}

// 输入多项式系数和指数
void inputPolynomial(Polynomial *poly) {
    for (int i = 0; i < poly->size; i++) {
        printf("请输入第 %d 项的系数和指数：", i + 1);
        scanf("%f %d", &(poly->terms[i].coef), &(poly->terms[i].exp));
    }
}

// 输出多项式
void outputPolynomial(Polynomial *poly) {
    for (int i = 0; i < poly->size; i++) {
        printf("%.2f * x^%d", poly->terms[i].coef, poly->terms[i].exp);
        if (i != poly->size - 1) {
            printf(" + ");
        }
    }
    printf("\n");
}

// 多项式相加
Polynomial addPolynomials(Polynomial *poly1, Polynomial *poly2) {
    Polynomial result;
    int i = 0, j = 0, k = 0;
    result.terms = (Term *)malloc((poly1->size + poly2->size) * sizeof(Term));

    while (i < poly1->size && j < poly2->size) {
        if (poly1->terms[i].exp > poly2->terms[j].exp) {
            result.terms[k++] = poly1->terms[i++];
        } else if (poly1->terms[i].exp < poly2->terms[j].exp) {
            result.terms[k++] = poly2->terms[j++];
        } else {
            result.terms[k].coef = poly1->terms[i].coef + poly2->terms[j].coef;
            result.terms[k++].exp = poly1->terms[i].exp;
            i++;
            j++;
        }
    }

    while (i < poly1->size) {
        result.terms[k++] = poly1->terms[i++];
    }

    while (j < poly2->size) {
        result.terms[k++] = poly2->terms[j++];
    }

    result.size = k;
    return result;
}

// 多项式相乘
Polynomial multiplyPolynomials(Polynomial *poly1, Polynomial *poly2) {
    Polynomial result;
    int k = 0;
    result.terms = (Term *)malloc(poly1->size * poly2->size * sizeof(Term));

    for (int i = 0; i < poly1->size; i++) {
        for (int j = 0; j < poly2->size; j++) {
            result.terms[k].coef = poly1->terms[i].coef * poly2->terms[j].coef;
            result.terms[k++].exp = poly1->terms[i].exp + poly2->terms[j].exp;
        }
    }

    result.size = k;
    return result;
}

int main() {
    Polynomial poly1, poly2, addResult, multiplyResult;
    int size1, size2;

    printf("请输入第一个多项式的项数：");
    scanf("%d", &size1);
    initPolynomial(&poly1, size1);
    inputPolynomial(&poly1);

    printf("请输入第二个多项式的项数：");
    scanf("%d", &size2);
    initPolynomial(&poly2, size2);
    inputPolynomial(&poly2);

    printf("第一个多项式：");
    outputPolynomial(&poly1);

    printf("第二个多项式：");
    outputPolynomial(&poly2);

    addResult = addPolynomials(&poly1, &poly2);
    printf("两个多项式相加的结果：");
    outputPolynomial(&addResult);

    multiplyResult = multiplyPolynomials(&poly1, &poly2);
    printf("两个多项式相乘的结果：");
    outputPolynomial(&multiplyResult);

    free(poly1.terms);
    free(poly2.terms);
    free(addResult.terms);
    free(multiplyResult.terms);

    return 0;
}

使用该代码，可以实现输入两个二元多项式，并输出它们的相加和相乘的结果。