Is there a way to capture a window image via terminal by mentioning the window name?

I have a scenario,like to save image of a window which will be open using the C functions.I had smilar kind of code in Linux,I tried that in Mac.but not working as expected.So it will be better if any one can provide a C code or way to implement a code for capturing image of a window. I want to pass two arguments.1.Path to save the Image2.Window Name Thanks -Jaleel