search value in array with fork parallel process in c

Question

I have to write ac program (linux) to decide if a value is present in an array. The way I am supposed to do it is by using parallel processes (fork ). It has to be done in a divide an conquer kind of way, by splitting the array in 2 halfs, then there should pe a child process for each half. A process should return 1 if the value is found and i have to check each child until the last one. Then i have to return a sum of those returned values.

Can anyone explain me how to do this ? I am not familiar with the this whole fork thing.(Code is also helpful.) Thanks !!

Answer 1

in general, what is needed is:

main()
{
    pid1 = fork()
    if( 0 > pid1 )
    then handle error and exit

    if( 0 == pid1 )
    then child
        exit( searchHalf(ptrToFirstHalf, firstHalfLength ) )



    else 0 < pid1, so parent
        pid2 = fork()
        if( 0 > pid2 )
        then handle error and exit

        if( 0 == pid2 )
        then child
            exit( searchHalf( ptrToSecondHalf, secondHalfLength ) )


        else 0 < pid2, so parent
        endif
    endif

    -- only parent will get here --
    waitpid( pid1, &status1, 0 ) // gets returnValue from child1
    waitpid( pid2, &status2, 0 ) // gets returnValue from child2
    printf ... status1+status2
    return
} // end function: main

search( ptrTohalf, halfLength )
{
    ..performSearch..
    return( returnValue )
}