Fix C++ Segmentation Fault (core dumped): A Comprehensive Guide (2025)

Posted on: March 17, 2025

Ran into a "Segmentation Fault (core dumped)" in C++? This dreaded error can crash your program in an instant. In this 2025 guide, we’ll explore why it happens and how to fix it with practical solutions!

What Causes "Segmentation Fault (core dumped)" in C++?

A Segmentation Fault occurs when your program tries to access memory it’s not allowed to touch. Common culprits include:

• Invalid Pointers: Dereferencing a null or uninitialized pointer.
• Array Bounds Overflow: Accessing an array index beyond its size.
• Memory Corruption: Overwriting memory with incorrect data.

Here’s an example that triggers this error:

#include 
int main() {
    int* ptr = nullptr;
    std::cout << *ptr;  // Segmentation Fault
    return 0;
}

How to Fix It: 3 Solutions

Let’s tackle this error with these steps:

Solution 1: Validate Pointers Before Use

Check if pointers are valid before dereferencing them:

#include 
int main() {
    int* ptr = nullptr;
    if (ptr != nullptr) {
        std::cout << *ptr;
    } else {
        std::cout << "Pointer is null!";
    }
    return 0;
}

Solution 2: Stay Within Array Bounds

Ensure array accesses don’t exceed allocated memory:

#include 
int main() {
    int arr[5] = {1, 2, 3, 4, 5};
    // Wrong: accessing beyond bounds
    // std::cout << arr[10];  // Segmentation Fault

    // Fixed
    if (10 < 5) {
        std::cout << arr[10];
    } else {
        std::cout << "Index out of bounds!";
    }
    return 0;
}

Solution 3: Use Debugging Tools

Employ tools like GDB or Valgrind to pinpoint memory issues:

#include 
int main() {
    char* buffer = new char[10];
    // Wrong: writing past allocated memory
    // for (int i = 0; i < 20; i++) buffer[i] = 'a';  // Segmentation Fault

    // Fixed
    for (int i = 0; i < 10; i++) {
        buffer[i] = 'a';
    }
    std::cout << buffer;
    delete[] buffer;
    return 0;
}

Tip: Run with gdb ./your_program and use backtrace to find the fault location.

Quick Checklist

• Is your pointer valid? (Check for nullptr)
• Are array indices safe? (Verify bounds)
• Debugging needed? (Use GDB or Valgrind)

Conclusion

The "Segmentation Fault (core dumped)" is a notorious C++ error, but with these 2025 fixes, you can tame it. Master memory management, and share your toughest bugs in the comments below!