How can I enter space bar as input using scanf?

Question

I'm writing an fuction and I got a problem, the scanf function cant read spacebar " ", how can I solve it?

void add()
{
char choose2;   

FILE *fp;
struct booking book;    
system("cls");          
fp=fopen("hotelbooking.txt","a");
    if(fp == NULL)
    {   
        printf("There are no data file!");
    }
    else
    {
        printf("Add New Hotel Booking Record(s)\n");

        printf("  Name of Traveller: \n");  
        scanf("%s",book.travellername);
        fprintf(fp,"\n%s",book.travellername);

        printf("  Destination: ");  
        scanf("%s",book.destination);
        fprintf(fp,"\n%s",book.destination);                            
        fclose(fp);     
    }               
}

In the tervellername part, If I want to enter e.g. "Jason George", How can I scan the space bar between the name?

I'm using the structure below:

    struct booking
    {
    char travellername[20];
    char destination[20];
    }book;

You want only a newline (Return or Enter) to terminate the input? — StoryTeller - Unslander Monica, Mar 08 '17 at 06:44
I have tried gets() but it wont let me enter anythings, it just skip the line — Kin Hang Lee, Mar 08 '17 at 06:46
@StoryTeller I want something similar to scanf but i can enter wors with space e.g. "The Pen" — Kin Hang Lee, Mar 08 '17 at 06:47
Then the duplicate question has all the approaches that can be suggested — StoryTeller - Unslander Monica, Mar 08 '17 at 06:48
@KinHangLee Welcome to Stack Overflow! [DO NOT use `gets()`, it is dangerous](http://stackoverflow.com/q/1694036/2173917). use [`fgets()`](https://linux.die.net/man/3/fgets) instead. — Sourav Ghosh, Mar 08 '17 at 06:50

score 3 · Answer 1 · answered Mar 08 '17 at 06:46

3

scanf() with %s format specifier stops scanning as soon as it hits a whitespace. You cannot scan space using it.

Quoting C11, chapter §7.21.6.2,

s Matches a sequence of non-white-space characters.

For a better and robust alternative, you can use fgets() to scan an entire line, terminated by a newline. Remember, in this case, fgets() scans and stores the terminating newline also in the supplied buffer, so you need to manually get rid of it, if that matters.

answered Mar 08 '17 at 06:46

Sourav Ghosh

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Detail: "scanf() with %s format specifier stops scanning as soon as it hits a whitespace" --> With `"%s"` leading spaces do not stop scanning, they are consumed and not saved. It is spaces after non-white-space that stops scanning with `"%s"`. This is not directly observed with OP's example which has a middle space. Good suggestion about `fgets()`. – chux - Reinstate Monica Mar 08 '17 at 15:39

score 1 · Answer 2 · edited May 23 '17 at 12:00

1

Try this

scanf("%[^\n]", book.travellername);

Input string will read space separated words and terminate upon encountering a newline character (i.e. \n). Also be Careful that this does not get buffer overflows. so define size of book.travellername accordingly.

update: I have updated the format specifier.

edited May 23 '17 at 12:00

Community

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answered Mar 08 '17 at 06:47

roottraveller

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The `s` isn't part of the format specifier. – StoryTeller - Unslander Monica Mar 08 '17 at 06:48
@StoryTeller I don't understand. this used to work for space separated input. – roottraveller Mar 09 '17 at 06:12
Look at the specification for scanf. There's `%s` and `%[]`. I also must mention that I didn't downvote, just wanted to point out what I thought was a typo. – StoryTeller - Unslander Monica Mar 09 '17 at 06:14

How can I enter space bar as input using scanf?

2 Answers2