Scanf() working differently with \n and '\n' supplied in format specifier

Question

#include "stdio.h"
int main(){
    float longi;
    float lati;
    char info[80];
    int started = 0;

    puts("Data=[");
    while((scanf("%f\n%f\n%s",&lati,&longi,info))==3){ //here is my doubt.


        printf("\n{latitude:%f, longitude:%f, info:%s},",lati, longi, info);
    }
    puts("\n]");    
}

The above code works as desired, but I figured it out by trial and error. This takes three inputs with the 'enter' key as separator. Initially I supplied:

'\n' instead of \n

in the format specifier, but that was of no use; it was taking only one input every time.

What's the difference between these two and how does scanf() handle them?

`'` inside the string is a character literal. This means scanf was expecting to receive the `'` character on the input. I anticipate that you didn't intend to supply one. — Alex Brown, Feb 12 '15 at 07:39
@AlexBrown yes i think, i will test it by supplying '\n' after giving each input except last. — OldSchool, Feb 12 '15 at 07:40
Why not just have `scanf("%f%f%s",&lati,&longi,info)` What is your worry with this? — Gopi, Feb 12 '15 at 07:40
@Gopi : it will not work, your code is not working, i have to supply spaces but i require that user press enter each time for entering the data input — OldSchool, Feb 12 '15 at 07:41
@Rouftantical What is not working I don't get why is `\n` needed in scanf() the format specifers will take care — Gopi, Feb 12 '15 at 08:02
@Rouftantical Who is pressing enter here ?? I am the user who is pressing the enter. scanf() is well defined why do you need `\n` in `scanf()` totally not required — Gopi, Feb 12 '15 at 12:00

score 2 · Accepted Answer · edited May 23 '17 at 10:24

2

So you had a scanf("%f'\n'%f'\n'%s",&lati,&longi,info) in your code.

When you break this code up:

%f - expect a float
' - expect a literal ' in the input
\n - expect a line break
' - expect a literal ' in the input

... and so on.

\n is a linebreak. Unquoted. The reason that some manuals show it in single quotes is a difference between a char that's represented by two symbols in code and a string literal.

See this question for more explanation.

Proper code is the one you already stated yourself:

scanf("%f\n%f\n%s",&lati,&longi,info)

edited May 23 '17 at 10:24

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answered Feb 12 '15 at 07:48

favoretti

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`\n` matches any sequence of white space (and is redundant here). To match a literal newline, `%*1[\n]` is needed – mafso Feb 12 '15 at 12:55

Scanf() working differently with \n and '\n' supplied in format specifier

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