将数据加载到共享内存中

如何解决将数据加载到共享内存中

我想知道如何将文本文件中的数据加载到C或C ++中的共享内存中。我想逐行将文件的内容分配到结构中，例如：

name: gaimi dancer
id: 443432
address: 123 Southbrook Dr. Mombai,In
PhoneNumber: 8876549300

以此类推，然后将这些结构加载到共享内存中。

我已经尝试了一切，但没有任何效果。我已经尝试过strcpy()和memcpy()，但它们没有用。

reader.cpp

#include <sys/shm.h>
#include <stdio.h>
#include<string>
#include<cstring>
#include<cstdlib>
using namespace std;

struct Stu_Info{
    char name[30];
    char id[20];
    char address[30];
    char PhoneNumber[20];
};

int main()
{
    // ftok for generating unique key
    key_t key = ftok("shm",6556);

    // shmget returns an identifier in shmid
    id = shmget(key,1024*4,0666|IPC_CREAT);
    //to make sure the shm made correctly
    if (id < 0){
        perror("create: shmget failed");
        exit(1);
    }else{
        cout << "The shm was craeted!!";
    }

    // shmat to attach to shared memory
    char *str = (char*) shmat(id,(void*)0,0);

    cout<<"Write Data : ";
    gets(str);

    printf("Data written in memory: %s\n",str);

    //detach from shared memory
    shmdt(str);    

    return 0;
}

writer.cpp

#include <iostream>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <stdio.h>
using namespace std;

int main()
{
    // ftok to generate unique key
    key_t key = ftok("shmfile",65);

    // shmget returns an identifier in shmid
    int id = shmget(key,1024,0666|IPC_CREAT);

    // shmat to attach to shared memory
    char *str = (char*) shmat(id,0);

    printf("Data read from memory: %s\n",str);

    //detach from shared memory
    shmdt(str);

    // destroy the shared memory
    shmctl(id,IPC_RMID,NULL);

    return 0;
}

text.txt

gaimi dancer
443432
123 Southbrook Dr. Mombai,In
8876549300
Yall S Player
465387
543 Saif Rd. Manama,BA
7665647833
Dean Rama
456339
908 Sea Ave. Manama,BA
4556748900
Maya Rab
677032
654 South 3rd St. Kwait,KW
3425435456
Patricia Carey
547839
320 Old navy St. Chiacgo,IL 
1112332534

解决方法

我在Mac命令行上运行cpp，我需要使用这种方式来执行此操作，并且还将使用信号量方式。我已经试过了这段代码，但是没有用。

while (getline(myFile,line)) //getline function to get the data line by line
            {
//                  cout << line << "\n"; // to print the content of the file

                  for(int j=0;j<=15;j++){//to create 15 student structs
                       for (int i=0; i<=15;i+4){ // to iterate in every 4 lines for 15 student strcts to save tha name.
                        strcpy(student[j][i].name,line);
                        name = student[j][i].name;
//                        cout <<student[j][i].name<<"\n";
                            memcpy(str,name,strlen(name)); // to load tha data into shared memory
                        }
                        for (int i=1; i<=15;i+4){ // to iterate in every 4 lines for 15 student strcts to save the id.
                            strcpy(student[j][i].id,line);
                            id = student[j][i].id;
                            memcpy(str,id,strlen(id)); // to load tha data into shared memory
                        }
                        for (int i=2; i<=15;i+4){ // to iterate in every 4 lines for 15 student strcts to save the address.
                            strcpy(student[j][i].address,line);
                            address = student[j][i].address;
                            memcpy(str,address,strlen(address)); // to load tha data into shared memory
                        }
                        for (int i=3; i<=15;i+4){ // to iterate in every 4 lines for 15 student strcts to save phone number.
                            strcpy(student[j][i].PhoneNumber,line);
                            PhoneNumber = student[j][i].PhoneNumber;
                            memcpy(str,PhoneNumber,strlen(PhoneNumber)); // to load tha data into shared memory
                        }
                  }
            }

          myFile.close();
    } else{cout << "unable to open a file!";}