实用的程序员编程工具

				#include 
				#include 
				#include 
				
				void main(int argc, char *argv[])
				 {
				   if(argc!=4)
				    {
				      cout 				      exit(1);
				    }
				   fstream out(argv[1], ios::in | ios::out | ios::binary);
				   if(!out)
				    {
				      cout 				      exit(1);
				    }
				   out.seekp(atoi(argv[2]), ios::beg);
				   out.put(*argv[3]);
				   cout 				   out.close();
				 }