How to use ImageMagick/GraphicsMagick (C) API to convert image from one format to another?

From: sigsegv11 (sigsegv11_at_gmail.com)
Date: 11/29/05 

Date: 28 Nov 2005 19:15:43 -0800

hi, all:

        I want to convert my pixmap file(such as .ppm) to JPEG file. How can I
do this with ImageMagick/GraphicMagick's C API? I tried to find it in
their website/documentation but that didn't help too much. A piece of
code is greatly appreciated.

        regards.