clang-tidy - cppcoreguidelines-prefer-member-initializer — Extra Clang Tools 21.1.8 documentation

# Extra Clang Tools 21.1.8 documentation

## clang-tidy - cppcoreguidelines-prefer-member-initializer

# cppcoreguidelines-prefer-member-initializer

Finds member initializations in the constructor body which can be converted into member initializers of the constructor instead. This not only improves the readability of the code but also positively affects its performance. Class-member assignments inside a control statement or following the first control statement are ignored.

This check implements C.49 from the C++ Core Guidelines.

Please note, that this check does not enforce rule C.48 from the C++ Core Guidelines. For that purpose see check modernize-use-default-member-init.

## Example 1

    class C {
      int n;
      int m;
    public:
      C() {
        n = 1; // Literal in default constructor
        if (dice())
          return;
        m = 1;
      }
    };

Here `n` can be initialized in the constructor initializer list, unlike `m`, as `m`’s initialization follows a control statement (`if`):

    class C {
      int n;
      int m;
    public:
      C(): n(1) {
        if (dice())
          return;
        m = 1;
      }
    };

## Example 2

    class C {
      int n;
      int m;
    public:
      C(int nn, int mm) {
        n = nn; // Neither default constructor nor literal
        if (dice())
          return;
        m = mm;
      }
    };

Here `n` can be initialized in the constructor initializer list, unlike `m`, as `m`’s initialization follows a control statement (`if`):

    C(int nn, int mm) : n(nn) {
      if (dice())
        return;
      m = mm;
    }