I am trying sort a number in a linked list from small to big.
But its not working !
the debugger says there are a problem when i put the second number into the
list ( in main )but i dont know why .
Any help ?
#include<stdio.h>
#include<stdlib.h>
typedef struct list list;
struct list{
int a;
list *nxt;
};
void sort(list *l){
int temp,tp;
list *AIDE,*k;
k=AIDE=(list*)malloc(sizeof(list));
while (l->nxt!= NULL)
{
while (l->nxt->a < l->a)
{
temp=l->a;
l=l->nxt;
l->nxt->a=temp;
l=l->nxt;
while (l->a < AIDE->nxt->a )
{
tp=AIDE->a;
AIDE->a=l->a;
AIDE->nxt->a=tp;
AIDE=AIDE->nxt;
}
}
l=l->nxt;
}
while (k->nxt!= NULL)
{
l->a=k->a;
l=l->nxt;
k=k->nxt;
}
l->nxt=NULL;
}
int main() {
list *t,*s;
int n,i,c=0;
printf("\n how many number you need to enter? ");
scanf("%d",&n);
s=t=(list*)malloc(sizeof(list)*n);
while (c!=n)
{
printf("\n Donner le nb %d :",c+1);
scanf("%d",&t->a);
t=t->nxt;
c++;
}
t->nxt=NULL;
sort(s);
while (t->nxt!=NULL)
{
printf("%d",t->a);
}
return 0;
}
In the loop where you have the problem, what do you think the expression t=t->nxt would do?
When you enter the loop, t is pointing to allocated but uninitialized memory, therefore dereferencing e.g. t->nxt will lead to undefined behavior.
A simple solution would be to e.g. do
t->nxt = t++ + 1;
Related
i am trying to make a list that order integers in ascendant order during the insertation phase ,for some reason it gives me a wierd number after putting the list in the right order,can someone tell me where i messed up?or if you have any optimal version of this functionajout_liste_croissant()?
#include"liste.h"
#include<stdio.h>
#include<stdlib.h>
#include<assert.h>
void ajout_liste_croissant(element**l,int info)
{assert(*l);
element*nouv;
nouv=(element*)malloc(sizeof(element));
if(vide(*l))/*if list is empty will add the new info without comparing */
{
*l=nouv;
(*l)->cle=info;
(*l)->suivant=NULL;}
else
{element*courant,*q;
int inter;
courant=*l;
int trouve=0;
while(courant!=NULL&&!trouve)/*parcouring the list till the end or when finding a value bigger than the entered one*/
{if(info<courant->cle)
trouve=1;
else{q=courant;/*this pointer get the adress of the previous current position in the list*/
courant=courant->suivant;}}/*the current pointer move to next adress*/
if(trouve)
{inter=courant->cle;
courant->cle=info;/*exchanging values in case current positon is bigger than the entered value*/
info=inter;
nouv->cle=info;
nouv->suivant=courant->suivant;
courant->suivant=nouv;
}
else
/*if the list reaches end*/
{
nouv->cle=info;
q->suivant=nouv;/*adding the new element at the end of the list*/
nouv->suivant=NULL;}
}
}
void afficher(element*l)
{assert(!vide(l));
while(l!=NULL)
{printf("%d\n",l->cle);
l=l->suivant;}
}
There are not too many errors. But your code is absolutely unreadable. I do not know how you could read it and, therefore, debug it.
So, I added spaces, indentations, new lines ... and it works with minor changes. I let you discover these changes. This answer is not necessarily the best way to do it but, starting from your code, I tried to do the minimum of changes. Moreover, avoid French (text, function names, ...) in your code when you ask question on stackoverflow.
#include<stdio.h>
#include<stdlib.h>
#include<assert.h>
typedef struct element {
int cle;
struct element *suivant;
} element;
void creer_liste(element **l) {
assert(l);
*l=NULL;
}
int vide(element *l) {
return(l==NULL);
}
void ajout_liste_croissant(element **l,int info) {
assert(l);
element *nouv;
nouv=(element*)malloc(sizeof(element));
if( vide(*l) ) {
*l=nouv;
(*l)->cle=info;
(*l)->suivant=NULL;
} else {
element *courant,*q;
int inter;
courant=*l;
int trouve=0;
while ( courant != NULL && !trouve ) {
if(info<courant->cle)
trouve=1;
else {
q=courant;
courant=courant->suivant;
}
}
if(trouve) {
inter=courant->cle;
courant->cle=info;
info=inter;
nouv->cle=info;
nouv->suivant=courant->suivant;
courant->suivant=nouv;
} else {
nouv->cle=info;
q->suivant=nouv;
nouv->suivant=NULL;
}
}
}
void afficher(element *l) {
assert(!vide(l));
while(l!=NULL) {
printf("%d\n",l->cle);
l=l->suivant;
}
}
int main() {
element *data;
int nb,info;
creer_liste(&data);
printf("donner la taille de la liste:\n");
scanf("%d",&nb);
for(int i=0;i<nb;i++) {
printf("donner un entier:\n");
scanf("%d",&info);
ajout_liste_croissant(&data,info);
}
printf("_____________________\n");
afficher(data);
}
I am writing a C program to add 2 polynomials given by user then displaying it in a separate function but it is not adding anything. In fact, it is not giving any type of error message so I am very confused. I think the mistake can be in 'addpoly' function or display function. I don't know what I am doing wrong. Any type of help will be appreciated.
#include<stdio.h>
#include<stdlib.h>
#define MAX 3
struct polynomial
{
int coeff;
int exp;
struct polynomial *next;
};
typedef struct polynomial polynomial;
polynomial *p1=NULL,*p2=NULL,*p3=NULL, *head_address=NULL;
polynomial* create()
{
polynomial *head_address=NULL, *prev_address=NULL, *new_address=NULL;
int i;
for(i=0;i<MAX;i++)
{
new_address=(polynomial*)malloc(sizeof(polynomial));
printf("Enter coeff:\n");
scanf("%d",&new_address->coeff);
printf("Enter exp:\n");
scanf("%d",&new_address->exp );
new_address->next=0;
if(head_address==NULL){
head_address=prev_address=new_address;
}
else{
prev_address->next=new_address;
prev_address=new_address;
}}
return head_address; }
void polyadd(polynomial *p1, polynomial *p2,polynomial *p3)
{
//polynomial* p3=NULL;
while(p1->next!=NULL && p2->next!=NULL){
if(p1->exp > p2->exp){
p3->coeff=p1->coeff;
p3->exp=p1->exp;
p1=p1->next;
}
else if(p1->exp < p2->exp){
p3->coeff=p2->coeff;
p3->exp=p2->exp;
p2=p2->next;
}
else if(p1->exp==p2->exp){
p3->coeff=p1->coeff + p2->coeff;
p3->exp=p1->exp;
p1=p1->next;
p2=p2->next;
}
p3->next=(polynomial*)malloc(sizeof(polynomial));
p3=p3->next;
p3->next=NULL; }
while(p1->next || p2->next){
if(p1->next){
p3->exp=p1->exp;
p3->coeff=p1->coeff;
p1=p1->next;
}
else if(p2->next){
p3->exp=p2->exp;
p3->coeff=p2->coeff;
p2=p2->next;
}
p3->next=(polynomial*)malloc(sizeof(polynomial));
p3=p3->next;
p3->next=NULL;
}
}
void display(polynomial *temp){
polynomial *p3;
p3=temp;
temp=head_address;
while(temp->next!=NULL)
printf("%dx^%d",temp->coeff,temp->exp);
temp=temp->next;
if(temp->next!=NULL){
printf(" + ");
}
}
int main(){
polynomial *p1,*p2,*p3;
p1=create();
printf("Next:\n");
p2=create();
polyadd(p1,p2,p3);
printf("Result:\n");
display(p3);
return 0;
}
Your issue looks like a memory reference error. In your polyadd() function you're not mallocing as much as you need to. Your base p3 pointer for your linked list is still unallocated when you start referencing off it in your first while loop. To fix your memory issue you'll want to malloc p3 before using it and then make sure the subsequent ->next instances all get malloced before being used.
I don't think this is causing you issues currently but you also have global variables defined at the top and then defined again in main(). The local variables will be the only ones used as long as they're present but I would delete your globals and make sure you don't have unused duplicates to avoid confusion.
First, I need to create and show a list that ends with number 1000. That works well.
Then, I want to create another list with only the numbers that are divisible by 3 in the first list, but it doesn't work.
The worst thing is that it doesn't even tell me what's going on. It just gives error in the execution but the console doesn't say anything.
I will really appreciate any help.
I tried all.
#include <stdio.h>
#include <stdlib.h>
#include<time.h>
#define CANTIDAD_NUMEROS 13
#define CANTIDAD_NUMEROS2 6
#define DESDE 1
#define HASTA 10
typedef struct lista{
int num;
struct lista *sig;
}nodo;
void crear (nodo *pt, int, int);
void crear2 (nodo *pt, int, nodo *pt2);
void mostrar(nodo *pt);
int main()
{
int i=0;
int t=0;
nodo *prin;
nodo *prin2;
prin=(nodo*)malloc(sizeof(nodo));
prin2=(nodo*)malloc(sizeof(nodo));
crear(prin,i, t); //creates first list
mostrar (prin); //shows first list
crear2(prin,i, prin2); //gets 'divisible by 3' numbers
mostrar(prin2); // shows second list
return 0;
}
//creates list
void crear (nodo *registro, int cont, int t)
{
scanf("%d", &t);
registro->num = t;
if (registro->num == 1000)
registro->sig=NULL;
else
{
registro->sig=(nodo*)malloc(sizeof(nodo));
cont++;
crear (registro->sig,cont, t);
}
return;
}
//shows list
void mostrar (nodo *registro)
{
if (registro->sig !=NULL)
{
printf ("%d\n",registro->num);
mostrar (registro->sig);
}else{
printf("%d\n",registro->num);
}
return;
}
//creates second list with only numbers that are divisible by 3
void crear2 (nodo *registro, int cont, nodo *registroNuevo)
{
if ((registro->num % 3) == 0){
registroNuevo->num = registro->num;
registroNuevo->sig = (nodo*)malloc(sizeof(nodo));
}
if(registro->sig != NULL){
crear2(registro->sig,cont, registroNuevo->sig);
}else{
return;
}
}
I expect to have the 1st list shown (which it's happening) and also the 2nd list shown with the numbers that are divisible by 3, which doesn't happen.
First of all, I admire your dedication to recursion!
The problem is that in crear2, registroNuevo->sig is uninitialized which causes a segfault. I almost always start a function that operates on a recursive linked data structure by checking if the parameter node is null. If so, I can safely continue on with the body of the function. Following this logic of protecting against nulls, we need to pass the registroNuevo node along without touching it in the case when registro->num % 3 != 0 and ensure all of its fields are initialized.
Here's the corrected function:
void crear2(nodo *registro, int cont, nodo *registroNuevo)
{
if (registro) {
if (registro->num % 3 == 0) {
registroNuevo->num = registro->num;
registroNuevo->sig = NULL;
if (registro->sig) {
registroNuevo->sig = malloc(sizeof(nodo));
}
crear2(registro->sig, cont, registroNuevo->sig);
}
else {
crear2(registro->sig, cont, registroNuevo);
}
}
}
Having said that, this function is still a bit less than ideal for a couple reasons. First of all, the name is vague and could describe the behavior better. Also, if there are no items divisible by three, you've got a malloced node back in the calling scope that never gets initialized, so it's a bit brittle in that regard. Thirdly, even with a parameter, it feels like a highly specific function without much reusability factor that could be written iteratively inside the calling scope like:
#include <stdio.h>
#include <stdlib.h>
typedef struct nodo
{
int num;
struct nodo *sig;
} nodo;
nodo *crear(nodo *registro, int num)
{
nodo *n = malloc(sizeof(nodo));
n->num = num;
n->sig = registro;
return n;
}
void mostrar(nodo *registro)
{
if (registro)
{
printf("%d->", registro->num);
mostrar(registro->sig);
}
else puts("");
}
void free_lista(nodo *registro)
{
if (registro)
{
free_lista(registro->sig);
free(registro);
}
}
int main()
{
nodo *prin = NULL;
nodo *prin_div_3 = NULL;
for (int t; scanf("%d", &t) && t != 1000;)
{
prin = crear(prin, t);
}
nodo *tmp = prin;
while (tmp)
{
if (tmp->num % 3 == 0)
{
prin_div_3 = crear(prin_div_3, tmp->num);
}
tmp = tmp->sig;
}
mostrar(prin);
mostrar(prin_div_3);
free_lista(prin);
free_lista(prin_div_3);
return 0;
}
This isn't perfect--without tail nodes, adding to the list is a bit less than ideal, but dangling heads are eliminated, and hopefully it shows an alternate approach to organizing program logic and functions.
A few other remarks:
Always free memory that you've allocated. You can write a simple recursive routine to do so, like free_lista as shown in the above example.
Consider avoiding highly specific functions with hard-coded values like 3 and 1000. Make these parameters to maximize reusability.
crear2 never uses the cont member, and you have global constants that are unused. It's a good idea to clean these up to help clarify your debugging efforts and reduce visual clutter.
No need to cast the result of malloc.
if (registro->sig !=NULL) as the first line of a function is going to crash on a null. You don't need != NULL either. if (registro) { ... } is clearest and avoids problems with null parameters.
void crear2 (nodo *registro, int cont, nodo *registroNuevo) {
if ((registro->num % 3) == 0) {
registroNuevo->num = registro->num;
registroNuevo->sig = (nodo*)malloc(sizeof(nodo));
if (registro->sig != NULL)
crear2(registro->sig, cont, registroNuevo->sig);
}
else {
if (registro->sig != NULL)
crear2(registro->sig, cont, registroNuevo);
}
}
This is my approach, but you are still getting a final unexpected 0 at the last mostrar() call; and you still need to do the 'free' calls. I think you should avoid the recursive calls, there are easier ways to do it. Saludos.
I'm faced with a problem which I've been unable to tackle for quite some time.
I've been given a graph as follows,in a M x N matrix:
2 2
a b
a c
Note
I've interpreted the graph above as a matrix,only consisting of non-diagonal edges.
Here the first line represents values of M and N respectively.
The graph is only connected either along vertical,or adjacent direction,i.e.,up,down,left and right. diagonal edges not present.
In order to find the adjacency list of the graph(the desired output here):
a-b-c
b-a-c
c-a-b
Steps followed by me in the code:
1.Read M x N matrix into a 2D array.
2.Created a list of unique vertices of the graph as Unode[arrmax].
3.For each element of the matrix,if the character matches with an element of the unique vertices list,I've called the modify Adjacency List procedure that searches the neighbours of the concerned matrix vertex and populates/appends to the the Adjacency list if distinct nodes are found.
It takes as arguments, i,j,M,N,AdjList,number of elements in the list and makes the changes.
5.I've kept the list of nodes to be global for easy modification.
6.Next I intend to use the adjacency list produced to use in DFS procedure and find the DFS forest.
The Problem statement:
the input consists of a grid of size M X N. Each cell in the grid
contain a lower case letter of the English alphabet.In a natural way,
the cells are of two types: boundary cells and internal cells. Each
internal cell in the grid has four neighbours in one of the left,
right, top, down directions. A string of characters can be formed by
starting at any cell and traversing the grid through the neighbours.
You have to print all the possible strings subject to the following
constraints:
**No two characters in a string can be same
**No two strings can be same in the final output
**The strings should be printed in alphabetically sorted order.
INPUT:
First line contains two integers M and N
Next M lines contains N space separated characters each
OUTPUT:
Print all possible strings in sorted order and obeying the above constraints.
INPUT SIZE:
1 <= M, N <= 20
SAMPLE INPUT:
2 2
a b
a c
SAMPLE OUTPUT:
a ab abc ac acb b ba bc bca c ca cb cba
[UPDATE]:
Completely redesigned the code,used structures for the graph nodes,and one for handling indices.
Yet the result I'm getting:
a--b-a
b--a
a
c--a
My code[Relevant Portion]:
#include <stdio.h>
#include<stdlib.h>
#include<string.h>
#define ADJMAX 20
#define arrmax 400
typedef struct uniq_node{
char ch;
char AdjList[ADJMAX];
int numofelem;
int visited;
}unode;
unode Ulist[arrmax];
int uniq_tot=0;
typedef struct index
{
int i,j;
}Ind;
Ind indx;
int charcomp(char sch,char arr[],int arrlim);
void adjModify(unode*,char*,int,int,Ind);
int chIndex(int,int,int,int);
int main(void) {
int mvar,nvar;
char str[15],*token;
long integer;
/*To scan the values of M & N*/
scanf("%d %d\n",&mvar,&nvar);
int iter,iterv,jterv;
/*To create the character matrix of M x N*/
char cmat[mvar][nvar];
/*Initializing the unique nodes list*/
/*To read-in the matrix from the stdin:-A LOT OF HARD WORK*/
for(iterv=0;iterv<mvar;iterv++)
{
fgets(str,50,stdin);
jterv=0;
token=strtok(str," ");
while(token)
{
/*Assigning value to the character matrix*/
cmat[iterv][jterv]=*token;
/*Code to populate the list of unique elements*/
if(charcomp(*token,Ulist[uniq_tot].AdjList,uniq_tot)==3)
{
Ulist[uniq_tot].ch=*token;
uniq_tot++;
Ulist[uniq_tot].numofelem=1;
Ulist[uniq_tot].AdjList[0]=*token;
//Ulist[uniq_tot].visited=0;
}
jterv++;
token = strtok(NULL, " ");
}
}
/*To populate the adjacency lists */
char ch;
for(iterv=0;iterv<mvar;iterv++)
{
for(jterv=0;jterv<nvar;jterv++)
{
ch=cmat[iterv][jterv];
indx.i=iterv;
indx.j=jterv;
for(iter=0;iter<uniq_tot;iter++)
{
if(ch==Ulist[iter].ch)
break;
}
adjModify(&Ulist[iter],(char*)cmat,mvar,nvar,indx);
}
}
/*for(iter=0;iter<uniq_tot;iter++)
{
printf("%c",Ulist[iter].ch);
printf("\n%s\n",Ulist[iter].AdjList);
for(iterv=0;iterv<Ulist[iter].numofelem;iterv++)
{
printf("-%c",Ulist[iter].AdjList[iterv]);
}
printf("\n");
}*/
return 0;
}
int chIndex(int i,int j,int mvar,int nvar)
{
return (i>=0 && i<mvar && j>=0 && j<nvar);
}
void adjModify(unode* Unode,char* mat,int mvar,int nvar,Ind mind)
{
int idum,jdum;
if(chIndex(mind.i,mind.j-1,mvar,nvar))
{
idum=mind.i;
jdum=mind.j-1;
if(charcomp(*(mat+idum*nvar+jdum),Unode->AdjList,Unode->numofelem)==3)
{
++Unode->numofelem;
Unode->AdjList[Unode->numofelem]=*(mat+idum*nvar+jdum);
printf("\nI'm here in coord:(%d,%d), with element: %c, and AdjList: %s for character: %c",idum,jdum,*(mat+idum*nvar+jdum),Unode->AdjList,Unode->ch);
}
}
if(chIndex(mind.i,mind.j+1,mvar,nvar))
{
idum=mind.i;
jdum=mind.j+1;
if(charcomp(*(mat+idum*nvar+jdum),Unode->AdjList,Unode->numofelem)==3)
{
++Unode->numofelem;
Unode->AdjList[Unode->numofelem]=*(mat+idum*nvar+jdum);
printf("\nI'm here in coord:(%d,%d), with element: %c, and AdjList: %s for character: %c",idum,jdum,*(mat+idum*nvar+jdum),Unode->AdjList,Unode->ch);
}
}
if(chIndex(mind.i-1,mind.j,mvar,nvar))
{
idum=mind.i-1;
jdum=mind.j;
if(charcomp(*(mat+idum*nvar+jdum),Unode->AdjList,Unode->numofelem)==3)
{
++Unode->numofelem;
Unode->AdjList[Unode->numofelem]=*(mat+idum*nvar+jdum);
printf("\nI'm here in coord:(%d,%d), with element: %c, and AdjList: %s for character: %c",idum,jdum,*(mat+idum*nvar+jdum),Unode->AdjList,Unode->ch);
}
}
if(chIndex(mind.i+1,mind.j,mvar,nvar))
{
idum=mind.i+1;
jdum=mind.j;
if(charcomp(*(mat+idum*nvar+jdum),Unode->AdjList,Unode->numofelem)==3)
{
++Unode->numofelem;
Unode->AdjList[Unode->numofelem]=*(mat+idum*nvar+jdum);
printf("\nI'm here in coord:(%d,%d), with element: %c, and AdjList: %s for character: %c",idum,jdum,*(mat+idum*nvar+jdum),Unode->AdjList,Unode->ch);
}
}
}
/*Comparison routine*/
int charcomp(char fchar,char arr[],int ucindex)
{
int ivar;
for(ivar=0;ivar<ucindex;ivar++)
{
if(arr[ivar]==fchar)
return;
}
return 3;
}
I think you can skip creating individual nodes for every element in the 2D array. Having the 2D array implies a structured connectivity. When it starts getting large, traversing all these elements may become cumbersome.
My recommended approach would be the following:
Scan of the matrix and pull unique nodes. i.e. start with a scan and have the simple list a,b,c (you'll need to sort them).
Create a struct for each unique node consisting the number of paths you currently have and an array of char arrays to store each one in. i.e. char** myArray={{a},{ab},{abc},{ac},{acb}} would be the one for a (This is of course unknown when you start).
Loop through your unique nodes, and one by one find the location in the 2D array. Don't save them, just go through them one by one and do a scan function to look for all their paths.
The scan function should be recursive so it can go as far as it needs to while checking every possible path (recursive will help you check every direction at every node you traverse). Keep track of where you've been, and at ever step check that you have not already encountered that character.
When you can't go any further, make sure the string has not already been included, if it has continue to the next path, if not add it to the list.
this is my code in c++ without any library that can work in c but you just have to use in c printf instead of cout and instead of class use struct that's all. I also write code for breadth first traversal see below.
and include the header file also
// #include <stdio.h>
//#include<stdlib.h>
#include<iostream
using namespace std;
class Node {
public:
int data;
Node* next;
Node(int data) {
this->data=data;
this->next=NULL;
// cout<<"from node file"<<endl;
}
};
class Queue {
Node * head;
Node * tail;
int length;
public:
Queue() {
head=NULL;
tail=NULL;
length=0;
}
bool isEmpty() {
return length==0;
}
int size() {
return length;
}
int front() {
if(head==NULL) {
cout<<"Empty Queue"<<endl;
return 0;
}
return head->data;
}
void enqueue(int element) {
Node * newNode =new Node(element);
if(head==NULL) {
head=newNode;
tail=newNode;
}else{
tail->next=newNode;
tail=newNode;
}
length++;
}
int dequeue() {
if(head==NULL) {
cout<<"Empty queue"<<endl;
return 0;
}
int output= head->data;
Node * temp=head;
head=head->next;
temp->next=NULL;
delete temp;
length--;
return output;
}
};
class AdjList{
public:
Node * head;
AdjList() {
head=NULL;
//cout<<"from adlist"<<endl;
}
void add (int data) {
Node * newNode=new Node(data);
if(head==NULL) {
head=newNode;
}else {
Node* temp=head;
while(temp->next!=NULL) {
temp=temp->next;
}
temp->next=newNode;
}
}
};
class Graph{
public:
int v;
AdjList* adjList;
Graph(int v) {
this->v=v;
adjList=new AdjList[v];
}
void addEdge(int src, int dest) {
adjList[src].add(dest);
///for bidrectional add below code
//adjList[dest].add(src);
}
void print(){
for(int i=0;i<v;i++){
Node *temp = adjList[i].head;
cout << i << " -> ";
while(temp != NULL)
{
cout << temp->data << " ";
temp = temp->next;
}
cout << endl;
}
}
void bfs(int src) {
// using a queue also in this file how to add queue structure
Queue q;
bool* visited=new bool [v]{0};
q.enqueue(src);
visited[src]=true;
while(!q.isEmpty()) {
int node= q.front();
cout<<node<<" ";
q.dequeue();
Node *temp = adjList[node].head;
while(temp!=NULL){
if(!visited[temp->data]) {
q.enqueue(temp->data);
visited[temp->data]=true;
}
// cout<<"data "<<temp->data;
temp=temp->next;
/// how to traverse
}
}
}
};
int main(){
Graph g(6);
g.addEdge(0, 1);
g.addEdge(0, 2);
g.addEdge(1, 3);
g.addEdge(2, 3);
g.addEdge(3,4);
g.addEdge(4,5);
g.bfs(0);
// g.print();
return 0;
}
I have a small doubly-linked list application. I want to add elements inside the list and then display the list normally. At the output i get my inserted elements allright, but after them i get a bunch of strange numbers( such as .... 28482 -20048 2817 ...... )
I believe it's a problem of space allocation.
Any help is appreciated, thanks in advance!
# include <stdio.h>
# include <conio.h>
# include <string.h>
# include <stdlib.h>
typedef struct elem {
int number;
struct elem * urm;
struct elem * prec;
}nod;
nod *prim=NULL,*ultim=NULL, *local=NULL, *p=NULL;
void insert_element(int numb){
nod *local=(nod *)malloc(sizeof(nod));
local->number = numb;
if (prim==NULL){
prim=local;
ultim=local;
}
else{
ultim->urm = local;
local->prec = ultim;
ultim=local;
}
}
void load_data()
{
int i,n;
nod *c = (nod *)malloc(sizeof(nod));
printf("\n cate elemente va avea lista?");
scanf("%d", &n);
printf("avem %d elemente", n);
for(i=1;i<=n;i++){
printf("\n number: ");
scanf("%d", &c->number);
insert_element(c->number);
}
}
void list_left_to_right()
{
nod *p = (nod*) malloc(sizeof(nod));
p=prim;
while(p){
printf("%d ", p->number);
p=p->urm;
}
printf("\n");
}
int main()
{
int op;
do{
printf("\n1.Enter some data\n");
printf("2.Display left - > right the data\n");
printf("0.Exit\n");
printf("choice : ");
scanf("%d",&op);
switch(op){
case 1: load_data(); break;
case 2: list_left_to_right(); break;
case 0: break;}
}
while (op!=0);
return 0;
}
(1) You have a memory leak in list_left_to_right():
nod *p = (nod*) malloc(sizeof(nod));
p=prim;
This leaks the block returned by malloc().
(2)
void insert_element(int numb) {
nod *local=(nod *)malloc(sizeof(nod));
local->number = numb;
// TODO: set local->urm and local->prec to NULL
if (prim==NULL) {
prim=local;
ultim=local;
OK, so the first time insert_element() is called, the new element is both the head and the tail.
Bug: You need to set the urm and prec fields to NULL. They have undefined values initially.
}
else {
ultim->urm = local;
local->prec = ultim;
ultim=local;
}
}
After that, the subsequent elements are inserted as a new tail (ultim).
Bug: But again you need to make sure that local->urm is set to NULL.