Функция добавления в двусвязный список

При добавлении номера сохраняется какой-то мусор, в чем может быть ошибка?

#include<iostream>
#include"stdio.h"
#include"stdlib.h"
#include"string.h"
struct List
{
char name[11];
char surname[21];
char number[13];
bool flag;
List*prev;
List*next;
};
List*begin=NULL;
List*end=NULL;

List* check(List*tmp)
{
char number[13];
printf("Enter the name,please\n");
scanf("%11s",tmp->name);
while(strlen(tmp->name)>11)
{
    printf("\nYou type incorrect name");
    scanf("%11s",tmp->name);
}
printf("\nEnter the surname,please\n");
scanf("%21s",tmp->surname);
while(strlen(tmp->surname)>21)
{
    printf("\nYou type incorrect surname\n");
    scanf("%21s",tmp->surname);
}
printf("\nEnter the phone number,please\n");
bool ok;

do
{

    scanf("%13s",number);

ok=true;

for(int j=0;j<strlen(number);++j)
{


    if(isdigit(number[j])==0)
    {
        printf("Don't type number like this!vvedite nomer! \n");

        ok=false;

    }
}

}while(strlen(number)>12 || ok==false);
for(List*tmp=begin;tmp!=NULL;tmp=tmp->next)
{
    if(strcmp(number,tmp->number)!=0)
    {
        strcpy(tmp->number,number);

    }
    else
    {

    printf("Takoyi nomer est' \n");
        break;
    }

}
return tmp;
 }
void add()
{
List*tmp=(List*)malloc(sizeof(List));
if(tmp==0)
{
printf("Not good!\n");
exit(1);
}
if(begin==NULL && end==NULL)
{
    tmp=check(tmp);
    if(tmp!=false)
    {

    tmp->flag=true;
    printf("\nYour register succesfully added\n");

    tmp->next=0;
    tmp->prev=0;
    begin=end=tmp;
    }

    }
if(end==0)
{
    tmp=check(tmp);
    if(tmp!=false)
    {

    tmp->flag=true;
    printf("\nYour register succesfully added\n");
    tmp->prev=end;
    tmp->next=0;
    end->next=tmp;
    end=tmp;

}
}

}
void show()
{

for(List*tmp=begin;tmp!=NULL;tmp=tmp->next)
{
    if(tmp->flag==true)
    {

            printf("Name:%11s",tmp->name);

            printf("\nSurname:%21s",tmp->surname);

            printf("\nNumber:%13s",tmp->number);
            printf("\n");
        }
        }
        }
  int main()
 {
add();
show();

system("pause");
return 0;
 }