import gurobipy as grb model = grb.Model() # 定义变量 y1 = model.addVar(name='y1') y2 = model.addVar(name='y2') y3 = model.addVar(name='y3') y4 = model.addVar(name='y4') y5 = model.addVar(name='y5') y6 = model.addVar(name='y6') y7 = model.addVar(name='y7') y8 = model.addVar(name='y8') # 添加约束 model.addConstr(y1+y2>=9,'第1种钢管') model.addConstr(y3+y4>=13,'第2种钢管') model.addConstr(y2+y4+3*y5+2*y6+y7>=17,'第3种钢管') model.addConstr(2*y1+2*y3+y4+y5+2*y6+4*y7+5*y8>=22,'第4种钢管') model.addConstr(y1 >= 0) model.addConstr(y2 >= 0) model.addConstr(y3 >= 0) model.addConstr(y4 >= 0) model.addConstr(y5 >= 0) model.addConstr(y6 >= 0) model.addConstr(y7 >= 0) model.addConstr(y8 >= 0) # 目标函数 model.setObjective(y1+y2+y3+y4+y5+y6+y7+y8, grb.GRB.MINIMIZE) # 求解 model.optimize() print('目标函数值是：', model.objVal) if model.status == GRB.OPTIMIZE: model.printAttr('X')改写为C语言

对于这段 Python 代码的改写，需要先了解 Gurobi 的 C 语言 API。Gurobi 提供了 C 语言的 API，可以使用 C 语言来编写线性规划模型并求解。

以下是对 Python 代码的改写，使用 Gurobi 的 C 语言 API 实现：

#include <gurobi_c.h>

int main(int argc, char *argv[]) {
    // 创建环境
    GRBenv *env = NULL;
    int error = GRBloadenv(&env, NULL);
    if (error) {
        printf("Error: %s\n", GRBgeterrormsg(env));
        return 1;
    }

    // 创建模型
    GRBmodel *model = NULL;
    error = GRBnewmodel(env, &model, NULL, 0, NULL, NULL, NULL, NULL, NULL);
    if (error) {
        printf("Error: %s\n", GRBgeterrormsg(env));
        return 1;
    }

    // 定义变量
    double lb[] = {0, 0, 0, 0, 0, 0, 0, 0};
    double ub[] = {GRB_INFINITY, GRB_INFINITY, GRB_INFINITY, GRB_INFINITY, GRB_INFINITY, GRB_INFINITY, GRB_INFINITY, GRB_INFINITY};
    char *names[] = {"y1", "y2", "y3", "y4", "y5", "y6", "y7", "y8"};
    error = GRBaddvars(model, 8, 0, NULL, NULL, NULL, NULL, NULL, lb, ub, NULL, names);
    if (error) {
        printf("Error: %s\n", GRBgeterrormsg(env));
        return 1;
    }

    // 添加约束
    int ind1[] = {0, 1};
    double val1[] = {1, 1};
    error = GRBaddconstr(model, 2, ind1, val1, GRB_GREATER_EQUAL, 9, NULL);
    if (error) {
        printf("Error: %s\n", GRBgeterrormsg(env));
        return 1;
    }

    int ind2[] = {2, 3};
    double val2[] = {1, 1};
    error = GRBaddconstr(model, 2, ind2, val2, GRB_GREATER_EQUAL, 13, NULL);
    if (error) {
        printf("Error: %s\n", GRBgeterrormsg(env));
        return 1;
    }

    int ind3[] = {1, 3, 4, 5, 6, 7};
    double val3[] = {1, 1, 3, 2, 1, 4};
    error = GRBaddconstr(model, 6, ind3, val3, GRB_GREATER_EQUAL, 17, NULL);
    if (error) {
        printf("Error: %s\n", GRBgeterrormsg(env));
        return 1;
    }

    int ind4[] = {0, 2, 3, 4, 5, 6, 7};
    double val4[] = {2, 2, 1, 1, 1, 4, 5};
    error = GRBaddconstr(model, 7, ind4, val4, GRB_GREATER_EQUAL, 22, NULL);
    if (error) {
        printf("Error: %s\n", GRBgeterrormsg(env));
        return 1;
    }

    // 设置目标函数
    int ind[] = {0, 1, 2, 3, 4, 5, 6, 7};
    double val[] = {1, 1, 1, 1, 1, 1, 1, 1};
    error = GRBsetobjcoeffs(model, 8, ind, val);
    if (error) {
        printf("Error: %s\n", GRBgeterrormsg(env));
        return 1;
    }
    error = GRBsetobjsense(model, GRB_MINIMIZE);
    if (error) {
        printf("Error: %s\n", GRBgeterrormsg(env));
        return 1;
    }

    // 求解
    error = GRBoptimize(model);
    if (error) {
        printf("Error: %s\n", GRBgeterrormsg(env));
        return 1;
    }

    // 输出结果
    double objval;
    error = GRBgetdblattr(model, GRB_DBL_ATTR_OBJVAL, &objval);
    if (error) {
        printf("Error: %s\n", GRBgeterrormsg(env));
        return 1;
    }
    printf("目标函数值是：%g\n", objval);

    if (GRBgetintattr(model, GRB_INT_ATTR_STATUS, &error) == 0 && error == GRB_OPTIMAL) {
        int nvars = GRBgetnumvars(model);
        double *x = (double *) malloc(nvars * sizeof(double));
        if (x == NULL) {
            printf("Error: Failed to allocate memory.\n");
            return 1;
        }
        error = GRBgetdblattrarray(model, GRB_DBL_ATTR_X, 0, nvars, x);
        if (error) {
            printf("Error: %s\n", GRBgeterrormsg(env));
            return 1;
        }
        printf("解为：\n");
        for (int i = 0; i < nvars; i++) {
            printf("%s = %g\n", GRBgetvarname(model, i), x[i]);
        }
        free(x);
    }

    // 释放资源
    GRBfreemodel(model);
    GRBfreeenv(env);

    return 0;
}

需要注意的是，C 语言 API 中的变量名、约束系数等都需要使用数组来存储，同时约束的不等式符号也需要使用 Gurobi 提供的常量来表示。在输出解时，需要使用 GRBgetvarname 函数来获取变量名。