c++ - std::string::erase() 的 pos 为 string::npos 的定义行为是什么？

Question

C++11 标准对 string&erase (size_t pos = 0, size_t len = npos); 成员函数的行为有何规定参数作为 string::npos 传递？我认为它不应该删除任何内容，但也许它会抛出 out_of_range 异常？标准定义的行为是什么？

Answer 1

它抛出 std::out_of_range ，正如标准中明确规定的那样:

21.4.6.5 basic_string::erase [string::erase]

basic_string& erase(size_type pos = 0, size_type n = npos);

Requires: pos <= size()

Throws: out_of_range if pos > size().

Effects: Determines the effective length xlen of the string to be removed as the
smaller of n and size() - pos. The function then replaces the string controlled by *this with a string of length size() - xlen whose first pos elements are a copy of the initial elements of the original string controlled by *this, and whose remaining elements are a copy of the elements of the original string controlled by *this beginning at position pos + xlen.

Returns: *this.