What could the reason for showing " Enter a character :" twice and self executing function Insert() twice without input for second execution?

Question

Why this program to make a linked list of characters and printing currently added item is showing output twice ?

And I am new to data structure,so i wanna ask another question . Is this implementation in Insert function is done correctly by me?

Code

#include <stdio.h>
#include <stdlib.h>

struct Node
{
    char data;
    struct Node *next;
};
struct Node *Head;
void Insert(char data)
{
    struct Node *temp = (struct Node *)malloc(sizeof(struct Node));
    temp->data = data;
    temp->next = Head;
    Head = temp;
    printf("Data in  this Node: %c \n", temp->data);
    
}
int main()
{
    Head=NULL;
    char data;
    while (1)
    {
        printf("Enter a Character : ");
        scanf("%c", &data);
        if (data == '0')
            break;
        Insert(data);
    }
}

Output

PS C:\Users\Dell\OneDrive\Desktop\Data Structure1\Data Structure Text Book> cd "c:\Users\Dell\OneDrive\Desktop\Data Structure1\Data Structure Text Book\Linked list\" ; if ($?) { gcc practice1.c -o practice1 } ; if ($?) { .\practice1 }
Enter a Character : q
Data in  this Node: q
Enter a Character : Data in  this Node:

Enter a Character : w
Data in  this Node: w
Enter a Character : Data in  this Node:

Enter a Character : 0
PS C:\Users\Dell\OneDrive\Desktop\Data Structure1\Data Structure Text Book\Linked list>

@VladfromMoscow why inserting whitespace before %c worked for me sir. can you please explain me? — roshannepal_x, Jun 03 '21 at 08:14
If before a conversion specifier there is a blank then white space characters as for example the new line character '\n' will be skipped in the input buffer. — Vlad from Moscow, Jun 03 '21 at 08:44

score 1 · Accepted Answer · answered Jun 03 '21 at 07:59

This is because when you press q<RETURN>, with <RETURN> being the Return key, that puts a linefeed character in the input stream after the q character.

It's better to read a full line, then inspect that:

char line[128];
while (fgets(line, sizeof line, stdin) != NULL)
{
  Insert(line[0]);
}

What could the reason for showing " Enter a character :" twice and self executing function Insert() twice without input for second execution?

Code

Output

1 Answers1