Ytukyg

As I may or may not have stated in a previous question, I am a newbie to C Programming and only have experience previously with Java, so I am fairly incompetent at using Structs and Pointers and may not have grasped these concepts well on the first time.

So I was playing with C and when I tried out the following program below:

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#define buf_sz 32



struct friends {

    char name[buf_sz];

    int number;

};

typedef struct friends friend;



void addfriend (friend * friendArr, int index);

void removefriend (friend * friendArr);



void main () {



    int index;

    int troll;



    friend friendArr[50];



    printf("1. Add Friend Name, 2. Remove Friend. Other buttons. Do nothingn");

    scanf(" %d", &troll);



    while ((troll == 1) && (troll == 2)) {

        switch (troll) {

            case 1: addfriend(friendArr, index);

                index++;

                break;

            case 2: removefriend(friendArr);

                break;

            default: break;

        }

    }



    for (int i = 0; i < 50; i++) {

        if (friendArr[i].name != NULL) {

            printf("%st%dn", friendArr[i].name, friendArr[i].number);

        }

    }



}



void addfriend (friend * friendArr, int index) {



    char buf[buf_sz];

    int number;



    printf("Add a friend's namen");

    fgets(buf, buf_sz-1, stdin);

    sscanf(buf, " %s", friendArr[index].name);



    printf("Add his numbern");



    scanf(" %d", &number);

    friendArr[index].number = number;



}



void removefriend (friend * friendArr) {



    char buf[buf_sz];

    char name[buf_sz];

    int check;



    printf("Add a friend's name you wanna removen");



    fgets(buf, buf_sz-1, stdin);

    sscanf(buf, " %s", name);



    for (int i = 0; i < 50; i++) {

        if (friendArr[i].name == name) {

            strcpy(friendArr[i].name, "");

        }

    }



}

My Output was given as:

1. Add Friend Name, 2. Remove Friend. Other buttons. Do nothing

1

@R      2009984

        0

        624

        4

 v      144

        0

l�      685382481

        32767

��G�    364104144

       0

0�G�    368262747

       32517

@�G�    440903072

�       32517

        368167105

       32517

�G�     370332944

       32517

_�g     370428400

       32517

        368167105

       32517

        364032000

       0

        0

        32517

�I      368217097

       0

��G�    368166640

       32517

���     370428400

       0

'       0

        0

pQ      368182487

       32517

        370431760

       0

���     0

        0

8W      0

        32767

W       440904224

�       32517

���     370432664

       0

        0

        32517

��G�    368232864

       32767

Which is basically a bunch of strange numbers, which I do not get the meaning of.

The desired output would be a message to print the question add a user's name and number if 1 was pressed, and delete a user if 2 was pressed, then print all the users.

I believe the problem here is my passing of array to struct, but I am not sure.

I have searched Stack Overflow everywhere for possible places I have went wrong, but I could not find anything that helped.

Can you friendly people point out where I went wrong?

You need to initialise your variables:

void main () {



    int index = 0;    // <<-- THIS 

    int troll;



    // Make some friends

    friend friendArr[50];



    for (int i=0; i<50; i++)

        friendArr[i].name[0] = '';   // <<-- AND THE NAME

When you print out the friends list, the members names cannot be compared to NULL, since they are not pointers. (well they can be compared, but it does not make sense). It would be better, once the data-set is initialised to blank, to check to see if there's a name set.

for (int i = 0; i < 50; i++) 

{

    if (friendArr[i].name[0] != '') 

    {

        printf("%st%dn", friendArr[i].name, friendArr[i].number);

    }

}

Also as @Groo points out, it's not valid to compare C strings with ==. Use strcmp() instead. Here we test that strcmp() returns 0 when the strings are identical.

for (int i = 0; i < 50; i++) 

{

    if (strcmp(friendArr[i].name, name) == 0) 

    {

        strcpy(friendArr[i].name, "");

    }

}