c++ programming (tree structure) problem?

You can't use == to test char * strings in C or C++. You either need to use proper C++ strings (which *do* support the == operator) or if you have to use C strings for some reason then use the C string library function strcmp(), i.e. change:

....if (item == temp->key)

to:

....if (strcmp(item, temp->key) == 0)

(and don't forget to #include <cstring>).

a million) c ought to truly be declated as a char, at a minimum of casted into it:           char c; 2) input_head grow to be initialized exterior of your important function (evaluate putting it interior the important function or on the comparable line):           struct record *enter, *input_head = NULL; that ought to restore your issues =) $./q enter in an expression finding out a million, 2, 3! !3 ,2 ,a million gnitset struct record *enter, *input_head = NULL; int important(void){      char c;      int i = 0;      printf("enter in an expressionn"); ... reset of your code... complete code (no longer plenty replaced like all different solutions reported, merely the two very minor errors) #contain <stdio.h> #contain <stdlib.h> struct record {      char archives;      struct record *next; }; struct OR_list {      struct record *record ;      struct OR_list *OR_list; }; struct n_tree {      char archives;      struct OR_list *record; }; struct record *enter, *input_head = NULL; int important(void) {      char c;      int i = 0;      printf("enter in an expressionn");      together as((c =getchar()) != ('n')){           enter = (struct record*)malloc(sizeof(struct record));           enter->archives = c;           enter->next = input_head;           input_head = enter;      }      enter = input_head;      together as(enter){           printf("%c", enter->archives);           enter = enter->next;      }      return 0; }