Let's break down this issue step by step. The error you're seeing is specific to GCC's libstdc++ library, and it fires when an attempt is made to construct a std::string from a null pointer. Your code looks correct at a glance, so let's explore the likely culprits and fixes:

1. Fix Type Mismatch in Loop Variable #

You're using uint for your loop counter, but std::vector::size() returns a size_t type. On some systems (especially 64-bit), uint (typically unsigned int) and size_t (often unsigned long long) have different widths. This can lead to unexpected behavior in loop conditions, even if your debug output looks correct.

Replace uint with size_t to match the return type of size():

for (size_t i = 0; i < loaded.size(); ++i)
    processString(loaded[i]);

2. Verify Required Headers Are Included #

Missing or incomplete headers can cause silent compilation issues that manifest as runtime crashes. Ensure your code includes all necessary standard library headers, and uses proper namespace qualification:

#include <iostream>
#include <vector>
#include <string>

// Either use std:: prefixes or add this line (common for small projects)
using namespace std;

3. Test Minimal Isolated Scenarios #

To narrow down the issue, try these quick tests:

• In your Processor constructor, replace the vector loop with a direct call using a string literal:

  processString("test");
  

  If this still crashes, the problem isn't related to your Loader or vector—it's likely an issue with how processString is being called during object construction, or a compiler/environment problem.
• Test constructing Processor on the stack instead of the heap in main:

  int main(int argc, char *argv[]) {
      Processor proc;
      return 0;
  }
  

  This can rule out heap allocation-specific issues.

4. Check for Environment/Compiler Issues #

• If you're using an older version of GCC, try updating to a more recent release (e.g., GCC 8+). Older versions had edge-case bugs related to string construction and object initialization.
• Use memory debugging tools like valgrind to check for hidden memory corruption:

  valgrind ./your_program
  

  This will flag any invalid memory accesses that might be corrupting your string data before it reaches processString.

5. Rule Out External Code Interference #

If your simplified code still crashes, check if there are other parts of your project (like global variables, static initializers, or other classes) that might be corrupting memory before your Processor runs. Sometimes unrelated code can overwrite memory regions used by your strings.

Here's the revised version of your code incorporating the key fixes:

#include <iostream>
#include <vector>
#include <string>

using namespace std;

class Loader {
public:
    Loader() {}
    void loadAllId() { loaded_ids_.push_back("a"); }
    vector<string> loaded_ids_;
};

class Processor {
public:
    Processor() {
        loader_ = new Loader();
        loader_->loadAllId();
        vector<string> loaded = loader_->loaded_ids_;
        for (size_t i = 0; i < loaded.size(); ++i)
            processString(loaded[i]);
    }
    
    void processString(string s) {
        cout << s << endl;
    }
    
private:
    Loader* loader_;
};

int main(int argc, char *argv[]) {
    Processor proc;
    return 0;
}

内容的提问来源于stack exchange，提问作者Yanet