How to Correctly Allocate Memory for Structures Containing Strings in C ?

Allocating Structures Containing Strings with Malloc

When attempting to manage memory for a structure containing std::string members using malloc(), segfaults may occur. This is because malloc() provides raw memory allocation rather than constructing objects.

Using new for Object Allocation

To correctly allocate memory for a struct with std::string members, use new instead of malloc(). new will automatically construct the object in the allocated memory.

Example:

#include <iostream>
#include <string>

struct example {
  std::string data;
};

int main() {
  example *ex = new example; // Allocate memory using 'new'
  ex->data = "hello world";
  std::cout << ex->data << std::endl;
  delete ex; // Release allocated memory when done
}

Placement new for Raw Memory Management

If memory has already been allocated using malloc(), it's possible to use placement new to construct the object in that memory.

Example:

void *ex_raw = malloc(sizeof(example));
example *ex = new(ex_raw) example; // Construct the object in allocated memory using placement 'new'

However, using new directly is generally preferred over placement new for object construction.

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