tree_util_prob.c: In function ‘tree_node* read_tree(char*)’:
tree_util_prob.c:64:50: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]
     error("Decision Tree file can not be opened.");
                                                  ^
tree_util_prob.c:67:42: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]
     error("Decision tree invalid/absent.");
                                          ^
tree_util_prob.c:70:42: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]
     error("Decision tree invalid/absent.");
                                          ^
tree_util_prob.c: In function ‘tree_node* read_hp(FILE*)’:
tree_util_prob.c:192:45: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]
  error("Invalid/Absent hyperplane equation.");
                                             ^
tree_util_prob.c:196:51: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]
      error("Read-Hp: Invalid hyperplane equation.");
                                                   ^
tree_util_prob.c:198:66: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]
      error("Read_Hp: Invalid coefficient index in decision tree.");
                                                                  ^
util.c: In function ‘int* ivector(int, int)’:
util.c:84:60: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]
   if (v==NULL) error("Ivector : Memory allocation failure.");
                                                            ^
util.c: In function ‘float* vector(int, int)’:
util.c:101:59: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]
   if (v==NULL) error("Vector : Memory allocation failure.");
                                                           ^
util.c: In function ‘double* dvector(int, int)’:
util.c:118:60: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]
   if (v==NULL) error("Dvector : Memory allocation failure.");
                                                            ^
