C++ 中 只要一用 std 就 Segmentation fault: 11 该如何解决呢？

[kither]

添加 cin >> a; 按下回车就 报 Segmentation fault: 11
不知道怎么处理

client代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <string>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include "define.h"
#define DEFAULT_PORT 6666
int main(){
    int connfd = 0;
    string T;
    struct sockaddr_in client;
    T = "127.0.0.1";
    const char *hname = T.c_str();
    client.sin_family = AF_INET;
    client.sin_port = htons(DEFAULT_PORT);
    client.sin_addr.s_addr = inet_addr(hname);
    connfd = socket(AF_INET, SOCK_STREAM, 0);
    if(connfd < 0){
        printf("socket() failure!\n" );
        return -1;
    }
    if(connect(connfd, (struct sockaddr*)&client, sizeof(client)) < 0){
        printf("connect() failure!\n" );
        return -1;
    }
    Pkg mypkg;
    mypkg.head.num=1;
    string a;
    cin >> a;
    cout << a << endl;
    mypkg.head.index=10001;
    mypkg.content.sex='m';
    mypkg.content.score=90;
    mypkg.content.age=18;
    T = "xxxxxxxxxxxxxxxxxxxxxxxxxx";
    const char * temp= T.c_str();
    strncpy(mypkg.content.address,temp,sizeof(mypkg.content.address));
    
    ssize_t writeLen;
    int tLen=sizeof(mypkg);
    printf("tLen:%d\n" ,tLen);
    int iLen=0;
    char * pBuff= new char [1000];
    *(int*)(pBuff+iLen)= htonl(tLen);
    iLen+=sizeof( int);
    *(int*)(pBuff+iLen)= htonl(mypkg.head.num);
    iLen+=sizeof( int);
    *(int*)(pBuff+iLen)= htonl(mypkg.head.index);
    iLen+=sizeof( int);
    memcpy(pBuff+iLen,&mypkg.content.sex,sizeof( char));
    iLen+=sizeof( char);
    *(int*)(pBuff+iLen)= htonl(mypkg.content.score);
    iLen+=sizeof( int);
    memcpy(pBuff+iLen,mypkg.content.address,sizeof(mypkg.content.address));
    iLen+=(sizeof(mypkg.content.address));
    *(int*)(pBuff+iLen)= htonl(mypkg.content.age);
    iLen+=sizeof( int);
    writeLen= MySend(connfd, pBuff, iLen);
    if (writeLen < 0) {
        printf("write failed\n" );
        close(connfd);
        return 0;
    }
    else{
        printf("write sucess, writelen :%ld, iLen:%d, pBuff: %s\n",writeLen,iLen,pBuff);
    }
    close(connfd);
    return 0;
}

define.h代码：

#pragma pack(1)
#include <iostream>
using namespace std;
struct Header {
        int num ;// 包id
        int index ;// 学生编号
};
struct PkgContent {
        char sex ;// 性别
        int score ;// 分数
        char address [100];// 地址
    int age;
};
struct Pkg {
        Header head;
        PkgContent content ;
};

int MySend( int iSock, char * pchBuf, size_t tLen){
        int iThisSend;
        unsigned int iSended=0;
        if(tLen == 0)
               return 0;
        while(iSended<tLen){
               do{
                     iThisSend = send(iSock, pchBuf, tLen-iSended, 0);
              } while((iThisSend<0) && (errno==EINTR));
               if(iThisSend < 0){
                      return(iSended);
              }
              iSended += iThisSend;
              pchBuf += iThisSend;
       }
        return tLen;
}

makefile 文件：

all:client
client:client.o
	g++ -g -o client client.o
client.o:client.cpp define.h
	g++ -g -c client.cpp
clean:all
	rm all