c++ - std string vs char performance, best technique to delete parts from the beginning -

Well, I have to process a large part of the text, it is an analysis from the beginning of the linear end and I wonder What is the best way to do this: using char * or std :: string. While using the four * i, the pointer can change to the next position in the string.

  // Edit later: Some places are malling for the text str [] = "Text to analyze"; Char * orig = str; // process str + = processed_chars; // fast enough // process then // later: free (original);   
 But to use the string I might have to use std :: string :: erase - but it can make a copy, or byte or something else (I have a real implementation Do not know)  
  string str = "text to analyze"; // process str = str.erase (0, processed_chars);   
 Or is there a way to change the hidden indicator of std :: string?  
 Edit: Sylvain Dfresen requested more code here:  
  class tag {public: tags (fodder pch) {* pch = strstr (* pch , "& Lt;"); If (PP == faucet) return; Char * orig = * pch + 1; * Pch = strstr (* pch, "& gt;"); If (PP == faucet) return; * PCH + = sizeof (four); // rear & gt; // Process Inner Tag Data if (* (* pch-2)! = '/') {// while not auto-shutting down (! (** (pch == '& lt;' & amp; (* pch + 1) == '/')) {// to close the tag Search = Children = New tag (PP); Sublings.push_back (* child); } * Pch = strstr (* pch, "& gt;"); If (PP == faucet) return; * PCH + = sizeof (four); // rear & gt; // Add tag if the fabric tag is matched}}}   
 I use it for parsing a symbolic XML-like sign  
  char str [] = "& Lt; father & gt; & lt; child /> & lt; / fatherr & gt;"; Char * pch = str; Tag * root = new tag (and pp);   
 This code is ugly in hell form, I'm just starting with low-level pointer arithmetic and stuff, so far the visual components are used, so much more Not difficult   
 
 
 With  std :: string , you might  Std :: string :: iterator . Your code will be:  
  std :: string str = "text to analyze"; Std :: string :: iterator iter = str.begin (); // process iter + = processed_chars;