hint on ansi c

I am a student. And need help on following program. I want to make a c program.

I have to scan a sentence and I have to interchange a word from that sentence.
Example: Scan the sentence is " Drilling machine and Milling machine " . Replace the word "machine" by "operation". And output should be " Drilling operation and Milling operation"

Can any one help ?

Check the rules here. No homework problems please.

Check the rules here. No homework problems please.