/H (Restrict Length of External Names)
| Overview | How Do I | Compiler Options
The /Hnumber option restricts the length of external (public) names. The program can contain external names longer than number characters, but the extra characters are ignored. A space between /H and number is optional. The compiler imposes no limit on the length of external identifiers.
The limit on length includes any compiler-created leading underscore (_) or at sign (@). The compiler adds a leading underscore (_) to names modified by the __cdecl (default) and __stdcall calling conventions, and a leading at sign (@) to names modified by the __fastcall calling convention. It appends argument size information to names modified by the __fastcall and __stdcall calling conventions, and adds type information to C++ names.
You may find the /H option useful when creating mixed-language or portable programs, or when using tools that impose limits on the length of external identifiers.