The problem with my code is that it cannot read the linked list when I want to update the info of position 2 or 3 and so on. It only reads position 1. Here is my code.
#include <stdio.h>
#include <malloc.h>
#include <string.h>
#include <stdlib.h>
typedef struct Student{
int studno; // student number
char name[20]; // Student name
float per; // GWA
struct Student *next; // next student
}Student;
Student *head;
int count(Student *h);
void create(Student *h); // Add Student info
void deleteByPos(Student *h); // Delete Student info
void updateByPos(Student *h); // Edit Student info
void searchByPos(Student *h);// Search student on the list
void display(Student *h); // View all student's info
void printline();
int main(){
int ch;
do {
system("cls");
printline();
printf("\t STUDENT MANAGEMENT SYSTEM\n");
printline();
printf("1. ADD LIST\n");
printf("2. DELETE LIST\n");
printf("3. EDIT BY POSITION\n");
printf("4. SEARCH BY POSITION\n");
printf("5. VIEW ALL\n");
printf("0. EXIT\n");
printline();
printf("Enter you choice: ");
scanf("%d", &ch);
switch(ch){
case 1: create(head);
break;
case 2: deleteByPos(head);
break;
case 3: updateByPos(head);
break;
case 4: searchByPos(head);
break;
case 5: display(head);
break;
case 0: printf("Thank you \nHave a Nice Day!");
break;
}
printf("\n\n");
system("pause");
}while(ch !=0);
}
void create(Student *h){
int studno;
char name[20];
float per;
printline();
printf("Enter Student Number : ");
scanf("%d", &studno);
fflush(stdin);
printf("Enter Student Name : ");
scanf("%[^\n]s", &name);
printf("Enter Student GWA : ");
scanf("%f", &per);
if(h==NULL){
head = (Student*) malloc(sizeof(Student));
head -> studno = studno;
head -> per = per;
strcpy(head -> name,name);
head -> next = NULL;
}
else {
while(h->next != NULL)
h = h-> next;
h-> next =(Student*) malloc(sizeof(Student));
h-> next -> studno = studno;
strcpy(h-> next ->name, name);
h-> next -> per = per;
h-> next -> next = NULL;
}
}
int count(Student *h){
int cnt=0;
while (h != NULL){
h = h ->next;
cnt ;
}
return cnt;
}
void deleteByPos(Student *h){
int n = count(h);
int pos, i;
Student *tmp;
printf("Enter Position to Delete: ");
scanf("%d", &pos);
if(pos>n){
printf("\nINDEX OUT OF BOUNDS");
}else if(pos==1){ // To delete from first position
tmp = h;
head = h->next;
free(tmp);
printf("\nRECORD SUCCESSFULLY DELETED");
} else if (pos>0){
for (i=1; 1<pos-1; i )
h = h ->next;
tmp = h -> next;
h -> next = h -> next -> next;
free(tmp);
printf("\nRECORD SUCCESSFULLY DELETED");
}
}
void updateByPos(Student *h){
int n = count(h);
int pos, i;
printf("Enter Position to Edit: ");
scanf("%d", &pos);
if(pos>n){
printf("\nINDEX OUT OF BOUNDS");
}else if(pos>0){
char name[20];
for(i=1; 1<pos;i )
h = h -> next;
printline();
fflush(stdin);
printf("Enter New Name: ");
scanf("%[^\n]s",h->name);
printf("Record Updated Successfully");
}
}
void searchByPos(Student *h){
int n = count(h);
int pos, i;
printf("Enter Position to Search: ");
scanf("%d", &pos);
if(pos>n){
printf("\nINDEX OUT OF BOUNDS");
}else if(pos>0){
for(i=1; 1<pos;i )
h= h -> next;
printline();
printf("\t STUDENT RECORD FOUND \n");
printline();
printf("%-10d%-20s%f\n", h->studno, h->name, h->per);
printline();
}
}
void display(Student *h){
printline();
printf("%-10s%-20s%s\n", "Stud No.", " Name", "Percentage");
printline();
while(h != NULL){
printf("%-10d%-20s%.2f\n", h->studno, h->name, h->per);
h = h ->next;
}
printline();
}
void printline(){
int i;
for(i=0; i<50; i )
printf("-");
printf("\n");
}
For example:
Let us say, The user inputs 4 students
STUDENT MANAGEMENT SYSTEM
- ADD LIST
- DELETE LIST
- EDIT BY POSITION
- SEARCH BY POSITION
- VIEW ALL
- EXIT
Enter your choice: 5
--------------------------------------------------
Stud No. Name Percentage
--------------------------------------------------
1 lisa 97.00
2 jisoo 98.00
3 jennie 99.00
4 rose 100.00
--------------------------------------------------
Press any key to continue . . .
The user wants to edit position 2
it becomes like this, the program should ask "Enter New Name:" and print "Record Updated Successfully"
--------------------------------------------------
STUDENT MANAGEMENT SYSTEM
--------------------------------------------------
1. ADD LIST
2. DELETE LIST
3. EDIT BY POSITION
4. SEARCH BY POSITION
5. VIEW ALL
0. EXIT
--------------------------------------------------
Enter you choice: 3
Enter Position to Edit: 2
Process returned -1073741819 (0xC0000005) execution time : 82.339 s
Press any key to continue.
It is the same problem in search function. I don't have a problem with other functions aside from the update and search functions. How to fix this?
CodePudding user response：
You have a typo 1 instead of i in your loop condition (both in updateByPos() and searchByPos()). I also moved the int i declaration into the loop:
for(int i=1; i<pos; i )
h = h->next;
If you move the UI functionality, say, to main() then you could reuse the searchByPos() in deletebyPos() and updateByPos() instead of duplicating essentially the same code. Also consider make Student *head a local variable in main() instead of a global variable. Your code already does the right thing by passing it around.
CodePudding user response：
for(int i=1; i<pos; i )
h = h->next;