undefined reference to `_exit'
Hi Jitendra,
If you transfer code from IAR, the problem is related to the different standard C libraries used (IAR has its own C library and System Workbench uses a newlib-based library provided by linaro).
The best way to import from another tool is to create a standard System Workbench project, selecting the board and firmware library you want to use (StdPeriph or HAL) then copy just your application code and header files in the src and inc folders of the newly created project; do not copy any of the IAR-provided files, only your own source code and it should work without problem.
Bernard