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.. title:: clang-tidy - performance-inefficient-string-concatenation
performance-inefficient-string-concatenation
============================================
This check warns about the performance overhead arising from concatenating
strings using the ``operator+``, for instance:
.. code-block:: c++
std::string a("Foo"), b("Bar");
a = a + b;
Instead of this structure you should use ``operator+=`` or ``std::string``'s
(``std::basic_string``) class member function ``append()``. For instance:
.. code-block:: c++
std::string a("Foo"), b("Baz");
for (int i = 0; i < 20000; ++i) {
a = a + "Bar" + b;
}
Could be rewritten in a greatly more efficient way like:
.. code-block:: c++
std::string a("Foo"), b("Baz");
for (int i = 0; i < 20000; ++i) {
a.append("Bar").append(b);
}
And this can be rewritten too:
.. code-block:: c++
void f(const std::string&) {}
std::string a("Foo"), b("Baz");
void g() {
f(a + "Bar" + b);
}
In a slightly more efficient way like:
.. code-block:: c++
void f(const std::string&) {}
std::string a("Foo"), b("Baz");
void g() {
f(std::string(a).append("Bar").append(b));
}
Options
-------
.. option:: StrictMode
When zero, the check will only check the string usage in ``while``, ``for``
and ``for-range`` statements. Default is `0`.
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