CODEWITHSUNDEEP
c++includeshared-librariesexternal
JNo
JNo

Reputation: 99

how to reduce compile time: in case of including an untouched header file

I have a function defined in file1.h as below:

/** file1.h **/
def testFunc(){}

file1.h is written once and will not be modified during the development. But I have to use testFunc() in my code say in file2.

/** file2.h **/
#include "file1.h"
testFunc(); //some sort of use

The problem is every time I make a change to file2.h, the compiler obviously also compiles file1.h, which takes time. Any suggestion on how to stop the compiler from compiling the file every time?

Upvotes: 0

Views: 574

Answers (1)

Aykhan Hagverdili
Aykhan Hagverdili

Reputation: 29975

You can use precompiled headers as a solution. How you do that depends on your Compiler and environment. Here is a start for GCC:

To create a precompiled header file, simply compile it as you would any other file, if necessary using the -x option to make the driver treat it as a C or C++ header file. You may want to use a tool like make to keep the precompiled header up-to-date when the headers it contains change.

A precompiled header file is searched for when #include is seen in the compilation. As it searches for the included file (see Search Path in The C Preprocessor) the compiler looks for a precompiled header in each directory just before it looks for the include file in that directory. The name searched for is the name specified in the #include with ‘.gch’ appended. If the precompiled header file cannot be used, it is ignored.

Upvotes: 2

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