Turbo C | scanf() | strange

[prateek]

Please see the source code
I am amazed
the scanf function has %[^\n] it should be %s
why this is working fine ??? what does this mean ??? ---> %[^\n] in scanf function ??

Source Code

#include<stdio.h>
#include<conio.h>
main()
{
    char str[20];
    clrscr();
    scanf("%[^\n]",str);
    printf("\n\n\n%s",str);
    getch();
} 

Output

prateek Reviewed by prateek on 12th Feb 2012. Turbo C | scanf() | strange Please see the source code I am amazed the scanf function has % it should be %s why this is working fine ??? what does this mean ??? ---> % in scanf function ?? Source Code #include<stdio.h> #include<conio.h> main() { Rating: 5

[Halcyon]

I guess that'll scan everything till you goto a new line O.o

^ - Not
\n - New line

[^\n] - Not a new line

[prateek]

yes yes,,

%[^\t] means it will keep accepting text until the user enters a TAB


thanks

[Bharat]

If you use a trailing space (a space at the end of the format string), your program appears to hang. Instead of entering a blank line or using space characters, you must enter what the value of str2 will be. The same for str3 and when it asks for str3's value, you would enter a value that won't appear. For example, use "%[^\n] " instead of "%[^\n]"/" %[^\n]". Your newline will be ignored as specified...and eaten by the trailing space in the format string. Since scanf didn't get a '\n' character, it will want more data. str2 will have that value and str3 will have str2's value.

[prateek]

#include<stdio.h>
#include<conio.h>
void call(int, int, int);
void main()
{
    clrscr();
    int a=10;
    call(a,a++,++a);
    getch();
}
void call(int x,int y, int z)
{
    printf("%d %d %d ",x,y,z);
} 

why the output is
12 11 11

???
i know post and pre increment perfectly
but what is happening here ???

[prateek]

here is what I think

first x will get the value 10,
then y will get value 10
then a will bcum 11
then again a will increase and bcum 12
then z will get 12

but it's not happening like that
the output is 12 11 11
why ??




or

it should give 10 11 12
as the output .. whats happning

[Halcyon]

You need to brush up the post/pre increment concepts a bit

But you also need to know that post/pre increment is machine dependent and may throw different results

Check this link: http://codepad.org/LmpZxhgD

[BJ@008]

[^\n] If I remeber right than this method is used to recieve a string with space through scanf().Normally you cannot do so directly in c if you do so then the string before space get accepted.

And for that operator one first

while calling first a++ get execute and passed i.e. z=11
then a++ i.e. y=11
then a i.e x=12

Hence output is 12 11 11

You must have a look on c function calling convention and post/pre increment function as Halcyon said.

[prateek]

hey
thanks brothers

i will surely do revision on post / pre increment & decrements

thanks a lot


rep added

[prateek]

@BJ@008

that means
the value is passed from right to left ? :-\
can you plz explain a bit more

while calling first a++ get execute and passed i.e. z=11
then a++ i.e. y=11
then a i.e x=12