Interview Questions

What is difference between the following syntax:
#include <filename.h>
#include "filename.h"
When to use each of the above?

How to include header files?

File inclusion can be done in the following 2 ways:

#include <filename.h>
#include "filename.h"

Each of the format specifies the path for the compiler to look for inclusion file filename.h

All standard header file like iostream, stdio.h are located in a standard path and they should be included as #include <filename.h>.

On Linux, gcc looks at:

All project specific user defined header files should be included in #include "filename.h" . Compiler now looks into same folder where the file being compiled is present, then at paths specified for compile option -iquote and then -I and then in above mentioned standard paths.