#include <iostream>
#include <string>
#include <cstdlib>

int main()
{
  string s = "Brian W. Kernighan;    The Practice of Programming;
    Addison Wesley";
  string f;
  size_t start, after;

  start = s.find_first_not_of(" \t;");
  after = s.find(";", start);
  cout << s.substr(start, after - start) << endl;

  return 0;
  
}

Output: 
Brian W. Kernighan