Tree data structure (Visual C++)

My file where is my structure - date.h 

#include <stdio.h>

struct Base

{

struct Base *left;

struct Base *right;

System::Int32 value;

};

and main program:

#pragma endregion

int *first_Value;

System::Void init_Random()

{

srand(time(NULL));

}

System::Boolean is_First(int x)

{

int i,sum;

sum=0;

for(i=1;i<x+1;i++)

if(x%i==0)

 ++sum;

if(sum==2)

 return true;

else

 return false;

}

System::Void itemsAdd(struct Base *base)

{

if(base!=NULL)

{

itemsAdd(base->left);

listBox1->Items->Add(base->value.ToString());

itemsAdd(base->right);

}

}

struct Base *my_Tree(struct Base *base, int my_value)

{

int temp;

temp=sizeof(struct Base);

if(base==NULL)

{

base=(struct Base*) malloc(temp);

base->value=my_value;

base->left=NULL;

                base->right=NULL;

}

else

if(base->value>my_value)

 base->left=my_Tree(base->left,my_value);

else

 base->right=my_Tree(base->right,my_value);

return (base);

}

private: System::Void Form1_Load(System::Object^  sender, System::EventArgs^  e) {

 init_Random();

 first_Value=new int[1000];

 int i,j;

 i=0;

 j=1;

 do

 {

if(is_First(j))

{

first_Value[i]=j;

i++;

j++;

}

else

j++;

 }while(i<1000);

}

private: System::Void button1_Click(System::Object^  sender, System::EventArgs^  e) {

delete first_Value;

                 Close();

}

private: System::Void button2_Click(System::Object^  sender, System::EventArgs^  e) {

int random_value,i;

                 struct Base *down;

                 down=NULL;

for(i=0;i<4;i++)

{

                 random_value=rand()%1000;

                 down=(struct Base*) my_Tree(down,first_Value[random_value]);

                 itemsAdd(down);

}

}

};

}