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我一直在挣扎了两天，试图解决这一问题的最终错误在我的代码，但似乎无法找到错误。该代码是设于（按顺序）：如何以正确的格式将数据发送回沿第二管？
- 接收来自用户的字符串（在这种情况下我）
- 创建子进程
- 发送串子进程
- 返修绳子，让每一个字以大写字母开头
- 字符串发送回父与变化
- 显示字符串
代码，直到家长阅读运行正常。一个例子输出为：
输入： “你好”
家长写道： “你好”
孩子在读 “你好”
孩子写道： “你好”
父阅读@＃$％^ $＃％^ & *或其他一些非标准字符，然后显示错误 -
double free or cor ruption（出）：0x00007ffeeebb2690 ***
下面是我的代码：
#include <iostream>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string>
#include <algorithm>
using namespace std;
int main(){
int fd[2];
int pfc[2];
int status = 0;
string val = "";
if(pipe(fd) == -1 || pipe(pfc) == -1) fprintf(stderr,"Pipe failed");
pid_t pid = fork();
// fork() returns 0 for child process, child-pid for parent process.
if (pid == 0){ // child: reading only, so close the write-descriptor
string writeval = "";
close(fd[1]);
// now read the data (will block)
read(fd[0], &val, sizeof(val));
cout << "Child reads " << val.c_str() << endl;
string temp = " " + val;
transform(temp.begin(), temp.end(), temp.begin(), ::tolower);
for(size_t i = 1; i < temp.length(); i++){
if(!isspace(temp[i]) && isspace(temp[i-1])){
temp[i] = toupper(temp[i]);
}
}
writeval = temp.substr(1, temp.length() - 1);
// close the read-descriptor
close(fd[0]);
close(pfc[0]);
cout << "Child writes " << writeval.c_str() << endl;
write(pfc[1], &writeval, sizeof(writeval));
close(pfc[1]);
exit(0);
}
else{
string readval = "";
string temp ="";
// parent: writing only, so close read-descriptor.
close(fd[0]);
// send the value on the write-descriptor.
while(getline(cin, temp)){
val += temp;
}
write(fd[1], &val, sizeof(val));
cout << "Parent writes " << val << endl;
// close the write descriptor
close(fd[1]);
//wait(&status);
close(pfc[1]);
read(pfc[0], &readval, sizeof(readval));
cout << "Parent reads " << readval << endl;
close(pfc[0]);
}
return 0;
}