Why does this simple C++ code segfault? [closed]

问题:

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Closed 2 years ago.

Here is the a.h header:

#include <string>

template <typename L>
class A
{
    L l;

public:
    A() : l("a-text") {}
    const std::string get() const { l.get(); } // <<<< Edit: missing return!
};

And here is a.cpp:

#include "a.h"
#include <iostream>

class L {
    const std::string v;

public:
    L(const std::string& v_): v(v_) {}
    const std::string get() const { return v; }
};

int main() {
    L l("l-text");
    std::cout << l.get().c_str() << std::endl;

    A<L> a;
    std::cout << a.get().c_str() << std::endl; // <<<< - this will report Segmentation fault

    return 0;
}

The first std::cout will work okay displaying l-text Yet the second std::cout will report Segmentation fault instead of displaying a-text.

Thanks in advance!

回答1:

Turn on your warnings. You're missing a return statement here:

const std::string get() const { l.get(); }