Why does my code skip over certain nodes? - c

Question

I'm writing this code to store data records of students' first name, last name, scores and zip codes. I have almost everything done but my Print() function doesn't print the first element of node 2(first name of 2nd student) and turns into an infinite loop when I input ore than 2 nodes, what am i doing wrong?
#include <stdio.h>
#include <string.h>
#include<stdlib.h>
void Insert(char first[20], char last[20], float data, char zip[50]);
void delete(int e);
void Print();
double median();
struct node
{
char first_name[20];
char last_name[20];
float score;
char zip_code[50];
struct node *ptr;
};
int n;
struct node* head =NULL;
struct node* tail=NULL ;
void Insert(char first[20], char last[20], float data, char zip[50])
{
struct node *temp=(struct node*)malloc(sizeof(struct node));
temp->ptr=NULL;
strcpy(temp->first_name,first);
strcpy(temp->last_name,last);
temp->score=data;
strcpy(temp->zip_code,zip);
if(head==NULL)
{
head=temp;
tail=temp;
return;
}
tail->ptr=temp;
tail=temp;
free(temp);
temp=NULL;
}
void delete(int e)
{
int i;
struct node *temp=(struct node*)malloc(sizeof(struct node));
temp=head;
if(e==1)
{
head=temp->ptr;
free(temp);
return;
}
else if(e==n)
{
while(temp->ptr->ptr!=NULL)
{
temp=temp->ptr;
}
temp->ptr=NULL;
free(temp->ptr);
return;
}
for(i=0; i<(e-2); ++i)
temp=temp->ptr;
struct node *temp1=temp->ptr;
temp->ptr=temp1->ptr;
free(temp1);
}
void Print()
{
struct node *temp=(struct node*)malloc(sizeof(struct node));
temp=head;
printf("Data entered is below: \n");
while(temp!=NULL)
{
printf("First Name: %s, Last Name: %s, Score: %.2f, Zip Code: %s",temp->first_name,temp->last_name,temp->score,temp->zip_code);
temp=temp->ptr;
printf("\n");
}
printf("\n\n\n");
}
double median()
{
double median,tmp;;
double *ex=(double*)malloc(sizeof(double));/*head*/
double *exe=(double*)malloc(sizeof(double));/*dynamic*/
ex=exe;
int i=1,term,j;
struct node *temp=(struct node*)malloc(sizeof(struct node));
temp=head;
while(i<=n)
{
temp->ptr;
*exe=temp->score;
exe++;
}
for(i=0; i<n; i++)
{
for(j=i+1; j<n; j++)
{
if( *(ex+i) > *(ex+j))
{
tmp = *(ex+i);
*(ex+i) = *(ex+j);
*(ex+j) = tmp;
}
}
}
if(n%2==0)
{
/*even;median=n/2-1*/
term=(n/2)-1;
median= (*(ex+(term-1)));
return median;
}
/*odd; median=n-1/2*/
term=(n-1)/2;
median= (*(ex+(term-1)));
return median;
}
int main()
{
char name1[20],name2[20], code[50];
float x;
int i,option,index;
printf("Enter the number of nodes: ");
scanf("%d",&n);
printf("Please enter the records of students in the following format(click enter for new students)\n");
printf("First_Name Last_Name Score Zip_Code\n");
for(i=1; i<=n; ++i)
{
scanf(" %s",name1);
scanf(" %s",name2);
scanf(" %f",&x);
scanf(" %s",code);
Insert(name1,name2,x,code);
}
printf("\n");
while(1)
{
printf("Choose one of the following options: \n");
printf("Print records (press 1)\nAdd a new record (press 2)\nDelete record(s) (press 3)\nSearch by zip code (press 4)\nSearch by score range (press 5)\nFind median score (press 6)\nExit the program (press 0)\n");
scanf("%d",&option);
switch(option)
{
case 0:
{
/*Exit Program*/
exit(0);
break;
}
case 1:
{
/*print*/
Print();
break;
}
case 2:
{
/*insert*/
getchar();
printf("Enter the new record in the following format: \nFirst_Name Last_Name Score Zip_Code\n");
scanf("%s",name1);
scanf("%s",name2);
scanf("%f",&x);
scanf("%s",code);
getchar();
Insert(name1,name2,x,code);
break;
}
case 3:
{
/*delete*/
printf("Enter the node/record to be deleted: ");
scanf("%d",&index);
delete(index);
printf("The deletion of record %d has been succesfully completed!\n\n",index);
break;
}
case 4:
{
/*search by zip*/
break;
}
case 5:
{
/*search by score*/
break;
}
case 6:
{
/*find median*/
printf("Median score for the entered records is: %f",median());
break;
}
}/*switch*/
}/*while*/
return 0;
}

Answer 1

The Insert function is holding a reference to freed data:
tail=temp;
free(temp);
Attempting to use the storage referenced by tail after it's been freed is an error.