遇到问题：在函数中开辟动态内存（已解决）

我定义了一个类，类中有指针成员，有函数，有的函数给这些指针成员开辟动态内存，有的函数引用这些动态内存的数据，有的函数释放这些动态内存，结果运行起来发现不可行。

class eigeninfo{
        public:
        int num_eig;
        int *eig_J;
        int *eig_pr;
        int *eig_u;
        int *eig_i;
        double *eig;

        void read(char *file_eig){
cout<<"1"<<endl;
                FILE *fp;
                if((fp=fopen(file_eig, "r"))==NULL)
                cout<<"error: failed to open "<<file_eig<<endl;
                char temps[temps_scale];
                char tempchar;
                int num_Jpi;
                fscanf(fp,"%d",&num_Jpi);
cout<<"num_Jpi="<<num_Jpi<<endl;
                // skip J, parity, Jpi_dim, calculate Jpi_Border
                for(int i=0;i<num_Jpi+2;i++){
                        fscanf(fp,"%[^ ]%*c",temps);
                }
cout<<"2"<<endl;
                // skip proton basises
                int num_basis_p;
                fscanf(fp,"%d",&num_basis_p);
                for(int i=0;i<num_basis_p+2;i++){
                        fscanf(fp,"%[^ ]%*c",temps);
                }
                // skip neutron basises
                int num_basis_n;
                fscanf(fp,"%d",&num_basis_n);
                for(int i=0;i<num_basis_n+2;i++){
                        fscanf(fp,"%[^ ]%*c",temps);
                }

cout<<"3"<<endl;
                // start reading what it wants
                fscanf(fp,"%d",&num_eig);

                //open memory for eig_J, eig_pr, eig_u, eig_i, eig
                int *eig_J=new int [num_eig];
                int *eig_pr=new int [num_eig];
                int *eig_u=new int [num_eig];
                int *eig_i=new int [num_eig];
                double *eig=new double [num_eig];

                for(int i=0;i<2;i++){
                        fscanf(fp,"%[^ ]%*c",temps);
                }

                for(int i=0;i<num_eig;i++){
                        fscanf(fp, "%d %d %d %d %lf",
                                        &eig_J[i],
                                        &eig_pr[i],
                                        &eig_u[i],
                                        &eig_i[i],
                                        &eig[i]);
                }
                fclose(fp);
        };
        void print(char *file_eig){
                cout<<"Read from "<<file_eig<<":";
                cout<<"num_eig="<<num_eig<<endl;
                cout<<"eig J parity u i eigwave ";
                for(int k=0;k<num_eig;k++){
                        cout<<"k="<<k<<endl;
                        cout<<eig_J[k]<<" ";
                        cout<<eig_pr[k]<<" ";
                        cout<<eig_u[k]<<" ";
                        cout<<eig_i[k]<<" ";
                        cout<<eig[k]<<" ";
                        cout<<" ";
                }
                cout<<endl;
        };
        void deletememory(){
                delete [] eig_J;
                delete [] eig_pr;
                delete [] eig_u;
                delete [] eig_i;
                delete [] eig;
        };
};

然后写了一个测试文件来测试它，调用 eigeninfo.read(), eigeninfo.print(), eigeninfo.deletememory()

结果在执行eigeninfo.print()时出现了：Segmentation fault (core dumped)

如果在一个函数中开辟动态内存，就在这个函数中引用和释放，到目前为止我发现，如果遵循这个原则就不会出错。

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2019/5/20 更

其实是因为代码里有错误， int * eig_J = new int [num_eig] ... 改为 eig_J = new int [num_eig] ... 就运行通过了