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issue with linked list !!IMPORTANT

This is a discussion on issue with linked list !!IMPORTANT within the C Programming forums, part of the General Programming Boards category; my new code looks like this Code: #include<stdio.h>#include<strings.h> #include<stdlib.h> #include<malloc.h> struct node { int data; struct node *next; }; typedef ...

  1. #31
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    my new code looks like this
    Code:
    #include<stdio.h>#include<strings.h>
    #include<stdlib.h>
    #include<malloc.h>
    
    
    struct node
    {
        int data;
        struct node *next;
    };
    
    
    typedef struct node link;
    
    
    link create_link(link *r);
    
    
    int main()
    {
        link *trys,*k;
        int i,j,num;
    
    
        trys=malloc(sizeof(link));
        k=trys;
        printf("Enter the Number  data\n");
        scanf("%d",&num);
        trys->data=num;
        trys->next=NULL;
        p: printf("\nDo you want to add more numbers?(Y=1/N=0)");
        scanf("%d",&i);
        if(i==1)
        {
            for(j=0;trys->next!=NULL;j++)
                    trys=trys->next;
            create_link(trys);
            {
                trys=k;
                for(j=0;trys->next!=NULL;j++)
                    trys=trys->next;
                printf("\nEnter the next Number data\n");
                scanf("%d",&num);
                trys->data=num;
            }
            trys=k;
            goto p;
        }
        else
        {
            printf("\nNumber dat entered by you is:\n");
            for(j=0;trys->next==NULL;j++)
            {
                printf("%d\n",trys->data);
            }
        }
        return 0;
    }
    
    
    link create_link(link *r)
    {
        link *addon;
    
    
        addon=malloc(sizeof(link));
        r->next=addon;
        addon->next=NULL;
        return *r;
    }

  2. #32
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    no no, != is correct, i seen your very first program and replied.

  3. #33
    C++ Witch laserlight's Avatar
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    This should be removed:
    Code:
    #include<malloc.h>
    You should change the use of goto to be a loop.

    You should free what you malloc.
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  4. #34
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    @pappu hmm u r correct dude @laserlight will goto create a kind of error *why to remove malloc.h?
    plus this is my current out put *(not able to print the values)
    Enter the Number data34


    Do you want to add more numbers?(Y=1/N=0)1


    Enter the next Number data
    23


    Do you want to add more numbers?(Y=1/N=0)1


    Enter the next Number data
    234


    Do you want to add more numbers?(Y=1/N=0)0


    Number dat entered by you is:


    Process returned 0 (0x0) execution time : 13.140 s
    Press any key to continue.

  5. #35
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    **if i am using != in print i am getting an infinite loop print of my first value entered.

  6. #36
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    This happens due to you have changed the trys to point its last node, its better to keep a head node that should not be moved.


    Quote Originally Posted by Amitesh93 View Post
    my new code looks like this
    Code:
    #include<stdio.h>#include<strings.h>
    
    #include<stdio.h>
    #include<strings.h>
    #include<stdlib.h>
    #include<malloc.h>
     
     
    struct node
    {
        int data;
        struct node *next;
    };
     
     
    typedef struct node link;
     
     
    link create_link(link *r);
     
     
    int main()
    {
        link *trys,*k;
        int i,j,num;
     
     
     //   k=trys;
     
        trys = (link *) malloc (sizeof(link)); 
        k = trys ;   //hereafter k is your head;
        printf("Enter the Number  data\n");
        scanf("%d",&num);
        trys->data=num;   //previously crash was happened here, now memory is allocated so here crash wont happen.
        trys->next=NULL;
        p: printf("\nDo you want to add more numbers?(Y=1/N=0)");
        trys = k;  // you are assigning head to trys, so every search will begin with head node.
        scanf("%d",&i);
        if(i==1)
        {
    /*        for(j=0;trys->next==NULL;j++)   //this also wrong, you have to try until u reach null  
                    trys=trys->next;
       */
            for(j=0;trys->next!=NULL;j++) 
                   trys=trys->next;
            create_link(&trys); // k points to the allocated memory
            {
    //         trys=k;     // here you are assigning k to trys, as of your code, memory is not allocated for trys, again while accessing trys may crash.
    //         for(j=0;trys->next==NULL;j++)   
    //             trys=trys->next;
                printf("\nEnter the next Number data\n");
                scanf("%d",&num);
                trys->data=num;
            }
           // trys=k;
            goto p;
        }
        else
        {
            printf("\nNumber dat entered by you is:\n");
            //for(j=0;trys->next==NULL;j++)
            for(j=0;trys->next!=NULL;j++)
            {
                printf("%d\n",trys->data);
            }
        }
        return 0;
    }
     
     
    link create_link(link **r)
    {
        link *addon;
     
     
        addon=malloc(sizeof(link));
        *r->next=addon;
        addon->next=NULL;
        return addon;
    }

  7. #37
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    @all who have helped me the program has been solved perfectly, uploading the final code working like a charm thanks all, the last and prior errors can be clarified by the code.
    Code:
    #include<stdio.h>#include<strings.h>
    #include<stdlib.h>
    #include<malloc.h>
    
    
    struct node
    {
        int data;
        struct node *next;
    };
    
    
    typedef struct node link;
    
    
    link create_link(link *r);
    
    
    int main()
    {
        link *trys,*k;
        int i,j,num;
    
    
        trys=malloc(sizeof(link));           /*trys initialisation*/
        k=trys;
        printf("Enter the Number  data\n");
        scanf("%d",&num);
        trys->data=num;                /*store the number in trys*/
        trys->next=NULL;
        p: printf("\nDo you want to add more numbers?(Y=1/N=0)");
        scanf("%d",&i);
        if(i==1)
        {
            for(j=0;trys->next!=NULL;j++)
                    trys=trys->next;            /*to send the pointer to last trys link for more addons*/
            create_link(trys);
            {
                trys=k;
                for(j=0;trys->next!=NULL;j++)                   /*moves the trys pointer to next links for adding numbers*/
                    trys=trys->next;
                printf("\nEnter the next Number data\n");
                scanf("%d",&num);
                trys->data=num;
            }
            trys=k;
            goto p;
        }
        else
        {
            printf("\nNumber dat entered by you is:\n");
            printf("%d\n",(*trys).data);      /*printing the first trys value*/
            for(j=0;trys->next!=NULL;j++)
            {
                trys=trys->next;                /*to increment the address of trys to next link*/
                printf("%d\n",(*trys).data);      /*printf takes value and not address*/
            }
        }
        free(trys);                /*freeing the malloc memory*/
        return 0;
    }
    
    
    link create_link(link *r)
    {
        link *addon;
    
    
        addon=malloc(sizeof(link));
        r->next=addon;
        addon->next=NULL;
        return *r;         /*return type needs to be juastified as type link*/
    }

  8. #38
    C++ Witch laserlight's Avatar
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    Quote Originally Posted by Amitesh93
    will goto create a kind of error
    It might lead to a logic error when you write code that is hard to understand because control jumps in unexpected ways. A loop can express your intention more clearly.

    Quote Originally Posted by Amitesh93
    why to remove malloc.h?
    It is non-standard and unnecessary since <stdlib.h> declares what you want.
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  9. #39
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    @laser light hmmm... i'll edit it thanx

  10. #40
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    your program seems to be good, however you are wasting some cpu cycles unneccessarily for searching part ?? from line no 35 to 41, you could try to reduce this by keeping another pointer as tail which has to point the last node initially at head node, whenever adding an element, you could add after tail node and move the tail node to newly allocated one(like queue). Lets try that and post the code, if its wrong.

    Quote Originally Posted by Amitesh93 View Post
    @all who have helped me the program has been solved perfectly, uploading the final code working like a charm thanks all, the last and prior errors can be clarified by the code.
    Code:
    #include<stdio.h>#include<strings.h>
    #include<stdlib.h>
    #include<malloc.h>
    
    
    struct node
    {
        int data;
        struct node *next;
    };
    
    
    typedef struct node link;
    
    
    link create_link(link *r);
    
    
    int main()
    {
        link *trys,*k;
        int i,j,num;
    
    
        trys=malloc(sizeof(link));           /*trys initialisation*/
        k=trys;
        printf("Enter the Number  data\n");
        scanf("%d",&num);
        trys->data=num;                /*store the number in trys*/
        trys->next=NULL;
        p: printf("\nDo you want to add more numbers?(Y=1/N=0)");
        scanf("%d",&i);
        if(i==1)
        {
            for(j=0;trys->next!=NULL;j++)
                    trys=trys->next;            /*to send the pointer to last trys link for more addons*/
            create_link(trys);
            {
                trys=k;
                for(j=0;trys->next!=NULL;j++)                   /*moves the trys pointer to next links for adding numbers*/
                    trys=trys->next;
                printf("\nEnter the next Number data\n");
                scanf("%d",&num);
                trys->data=num;
            }
            trys=k;
            goto p;
        }
        else
        {
            printf("\nNumber dat entered by you is:\n");
            printf("%d\n",(*trys).data);      /*printing the first trys value*/
            for(j=0;trys->next!=NULL;j++)
            {
                trys=trys->next;                /*to increment the address of trys to next link*/
                printf("%d\n",(*trys).data);      /*printf takes value and not address*/
            }
        }
        free(trys);                /*freeing the malloc memory*/
        return 0;
    }
    
    
    link create_link(link *r)
    {
        link *addon;
    
    
        addon=malloc(sizeof(link));
        r->next=addon;
        addon->next=NULL;
        return *r;         /*return type needs to be juastified as type link*/
    }

  11. #41
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    This code have memory leak, if you allocated more than one element, you have to free each and every element.
    instead of trying free(trys) you have to use


    Quote Originally Posted by Amitesh93 View Post
    @all who have helped me the program has been solved perfectly, uploading the final code working like a charm thanks all, the last and prior errors can be clarified by the code.
    Code:
    for ( ; k! = NULL; ) {
           trys = k->next ? k->next : NULL ;
          free (k);
           k = trys;
    }

  12. #42
    - - - - - - - - oogabooga's Avatar
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    This
    Code:
    trys = k->next ? k->next : NULL ;
    is equivalent to this
    Code:
    trys = k->next;

  13. #43
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    yeah, actually i thought of using trys = k ? k->next:NULL ; since we already checked null check for k, we could use trys = k->next.

    Quote Originally Posted by oogabooga View Post
    This
    Code:
    trys = k->next ? k->next : NULL ;
    is equivalent to this
    Code:
    trys = k->next;

  14. #44
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    @pappu on using the abuv edition the program stops working after printing the number(*it crashes)

  15. #45
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    Quote Originally Posted by pappu_uddad View Post
    This code have memory leak, if you allocated more than one element, you have to free each and every element.
    instead of trying free(trys) you have to use
    k!=NULL should be k->next!=NULL then the prog is working fine.
    *can you tell me how to check memory leaks can the compiler tell us or we need to self asses the program i do understand the memory leak phenomenon of malloc but is there any compiler driven method to get it accuratly.

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