title: System Calls - How to find a character within a string, if he character exists
body: <p>I'm extremelly new to System Calls. I think I can use Index but not quite sure how to implemented. Let's say I want to look up on a file with data for every ":" and '>"</p>
  
  <p>for example I have a myfile.txt with the following:</p>
  
  <p>hello: this is a testing
   for (1=zero i>10);
   this line should be written to the two files because it contains both the : and the ></p>
  
  <p>so I'm gonna open two files for writing and one for reading (myfile.txt) and when i find a line containing ":" I'll write it to the colon.txt file. When the line contains ">" character I'll write it to the greaterthen.txt file.  </p>
  
  <p>more comments: 
   Yes I need to implement buffer. </p>