Array and pointers to structures-CodePudding

So I have this structure

struct Data {
int id;
string message;
};

I am trying to create an array of struct pointers and fill it with values using this

Data *stack[10];
for(int i=0; i<10; i  ){
    stack[i] = (struct Data*) malloc(sizeof(struct Data));
    stack[i]->id = i;
    stack[i]->message = "message"   i;
}

however, I keep getting an error (segmentation fault when debugging) from stack[i]->message = "message" i; Can anyone please help understand what's causing the error and how to solve it?

CodePudding user response：

Below is the working example. You can use smart pointers for automatic memory management, that is the destructor will be called automatically when reference count goes to zero.

#include <iostream>
#include <memory>
using namespace std;
struct Data {
int id;
string message;
Data()
{
    std::cout<<"default consructor"<<std::endl;
}
~Data()
{
    std::cout<<"destructor "<<std::endl;
}
};
int main()
{
   std::cout << "Hello World" << std::endl; 
   std::shared_ptr<Data> stack[10];
  for(int i=0; i<10; i  ){
    
    stack[i] = std::make_shared<Data>();
    stack[i]->id = i;
    stack[i]->message = "message"   std::to_string(i);//make sure to convert the integer to std::string 
    }
    
   //check the value of id for first element in stack
    std::cout<<stack[1]->id<<std::endl;
   return 0;
}

You can also use new instead of malloc but then you will have to call delete explicitly. Note the use of std::to_string() to convert the integer i to string.