C/C++: stack overflow — infinite recursion or huge local array (Segmentation fault, 0xC00000FD)

Meaning

Each function call uses stack memory (typically 8 MB on Linux, 1 MB on Windows). Unbounded recursion, deep but legitimate recursion on big inputs, and arrays like int a[10'000'000]; inside a function exceed it. On Linux the process dies with a plain segmentation fault; on Windows you see 0xC00000FD.

Common causes

• Recursive function without a reachable base case
• Recursion depth proportional to input size (linked list, DFS on large graphs)
• Large arrays or objects declared as local variables
• Mutual recursion between functions or constructors/destructors
• Copy constructor that calls itself

Detailed fix by platform

Code examples

#include <vector>

long long sum_to(long long n) {              // infinite if called with n < 0
    if (n <= 0) return 0;                    // base case
    return n + sum_to(n - 1);
}

int main() {
    // int big[5'000'000];                   // 20 MB on the stack: crashes
    std::vector<int> big(5'000'000);         // heap: fine
    return static_cast<int>(sum_to(1000) % 256);
}

How to diagnose

1. Backtrace — Does the same function repeat?
2. Size — Any large local arrays?
3. Input — How deep does the recursion get?

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