Wsrtjtyk

This is the code for BFT(breadth first traversal) for a connected graph.
I run the code then I successfully make the adjacency list and also successfully print the adjacency list but after it program stops at when I take input from user to start the BFS from that inputed node.
scanf() is running infinitely or other error I can't able to identify.

#include<stdio.h>

#include<stdlib.h>



typedef struct root               //the adjacency list which have all the vertices

{

    int info;

    struct adjacent *adj;

    struct root *next;

} root;

typedef struct adjacent             //Linked list which store adjacent nodes of any nodes in adj list.

{

    int info;

    struct adjacent *adj;

} adjacent;



typedef struct node                    // to make queue to store nodes to be explored.

{

    int info;

    struct node *next;

} nodeQ;



void insert(nodeQ **ft,nodeQ **rr,int n)      // insert func of Q

{

    nodeQ * new=(nodeQ *)malloc(sizeof(nodeQ));

    new->info = n;

    new->next = NULL;

    if(*ft == NULL)

    {   

        *ft=new;

        *rr=new;

    }

    else

    {

        (*rr)->next = new;

        *rr = new;

    }

}

int delete(nodeQ **ft,nodeQ **rr)           //delete func of Q

{

    int value=(*ft)->info;

    nodeQ *temp=*ft;

    *ft=(*ft)->next;

    free(temp);

    if(*ft==NULL)

        *rr=NULL;

    return value;

}



void BFS(int total_nodes,int node_tobe_explored,root *head,nodeQ **ft,nodeQ **rr)

{

    printf("ff");

    int * visited=(int *)malloc(sizeof(int)*total_nodes);

    for(int i=0;i<total_nodes;i++)

        visited[i]=0;                                 //initialize all value in visited array with 0

    printf("aa");

    visited[node_tobe_explored] = 1;

    printf("%d",node_tobe_explored);

    while(1)                               // this loop iterates until all nodes are not explored.

    {

        root *t=head;

        while(t->info != node_tobe_explored)    // this find the node address(t) of the node_tobe_explored.

            t=t->next;

    printf("bb");

        adjacent * adj_node = t->adj;



        while(adj_node)

        {

            if(visited[adj_node->info] == 0)    //if that adjacent node is not visited then also we visit it.

            {

                int adj_node_val = adj_node->info;

                visited[adj_node_val] = 1;

                insert(ft,rr,adj_node_val);

                printf(", %d",adj_node_val);

            }

        }

            printf("cc");

        if(*rr==NULL)        //if Q is empty, means all nodes are explored, so we return.

            return;

        else                   //otherwise explore first node present in Q

            node_tobe_explored = delete(ft,rr);

    }

}



int main()

{ 

    char ch;

    int no,tot_nodes,start;

    nodeQ *front=NULL,*rear=NULL;

    printf("enter the no. of nodes: ");

    scanf("%d",&tot_nodes);

    root *head = NULL;

    no = tot_nodes;

    while(no!=0)

    {                                              //to make the main chain of adjacency list.

        root *new=(root *)malloc(sizeof(root));      

        new->info = no;

        new->adj = NULL;

        new->next = head;

        head = new;

        no--;

    }

    root *temp = head;

    while(temp!=NULL)

    {                                                  // to add the adjacent nodes to main chain.



        printf("enter the nodes adjacent to %d:n",temp->info);

        do

        {

            int element;

            printf("  enter node: ");

            scanf("%d",&element);

            adjacent *nw = (adjacent *)malloc(sizeof(adjacent));

            nw->info = element;

            nw->adj = temp->adj;

            temp->adj = nw;



            printf("more adjacent nodes y/n: ");

            ch=getchar();

            ch=getchar();

        }while(ch=='Y'||ch=='y');



        temp=temp->next;

    }

    printf("display of the structur of the linked list formed:n");

    root * head1=head;

    while(head1)                               // to display the formed adj. list.

    {

        printf("%d--",head1->info);

        adjacent *t = head1->adj;

        while(t)

        {   

            printf("%d,",t->info);

            t=t->adj;

        }

        printf("n");

        head1=head1->next;

    }



    do

    {

        printf("enter the node value from which you want to start BFS: ");

            printf("before [enter image description here][1]");

            int st;

        scanf("%d",&st);

            printf("after");

        BFS(tot_nodes,st,head,&front,&rear);             //calling BFS func.

        printf("do you want to print more traversals y/n: ");

        ch=getchar();

        ch=getchar();

    }while(ch=='Y'||ch=='y');

}

Excerpt from OPs source code:

    printf("do you want to print more traversals y/n: ");

    ch=getchar();

    ch=getchar();

}while(ch=='Y'||ch=='y');

The intention was probably to read a letter (y or n) and the n which confirmed the input.

So, the 2^ndch=getchar(); (for ENTER) overrides the previously read letter. The following fix would change this:

    printf("do you want to print more traversals y/n: ");

    ch=getchar();

    getchar(); /* ignore the returned value - it's just to consume 'n'. */

}while(ch=='Y'||ch=='y');

Btw. this is something which should have been uncovered by a step-wise debugging of the cited four lines...