[Solved] std::map crashes when doing m[0] [duplicate]

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Unfortunately (thanks C!) it is “possible” to construct a std::string from the integer 0, because it counts as a null pointer literal.

However, it’s not really possible:

Constructs the string with the contents initialized with a copy of the null-terminated character string pointed to by s. The length of the string is determined by the first null character. The behavior is undefined if [s, s + Traits::length(s)) is not a valid range (for example, if s is a null pointer).

You got a crash because you tried to create a std::string from a null pointer.

At least with GCC the result of this contract violation is an [unhandled] exception with a descriptive name:

terminate called after throwing an instance of 'std::logic_error'
  what():  basic_string::_M_construct null not valid

Unfortunately, though, you can’t rely on this, and you don’t get any warnings during build. ?

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solved std::map crashes when doing m[0] [duplicate]