2.2. The class to which CIN belongs is overloaded >; & gt operator, which makes it easier to enter, for example
Double d; CIN & gt； & gtd；
Scanf is different,
Double d; scanf("%lf "，& ampd)；
It looks a little troublesome.
In addition, cin is more secure and there will be no memory overflow.
char c； scanf("%lf "，& ampc)； //At this time, 8 bytes of space were needed, but only one was provided, and the memory overflowed.
Cin is safer.
char c； CIN & gt； & gtc； //Only enter characters, and it will not overflow.
3. From the bottom, cin in C++ and scanf in C use stdin as input source, but cin and scanf use different buffers. You can set buffer * * * to share through the sync_with_stdio () function in the ios header file.
C++ can also change the input source, but it is very complicated.
In fact, C++ encapsulates stdin, changes the concept of stream with stream and iterator, and C's scanf directly operates stdin.
4.cin
and
Format input function of c language
Precautions for use
(Note: The source code of this article does not contain the header file, so please edit it yourself during the experiment. )
Please watch and operate, so as to really understand the trick:
5.
Scan function ()
：
Commonly used are
( 1)
scanf("%s "，a)； //a
Is a pointer to a string;
Example:
int main(){
char a[20]；
scanf("%s "，a)；
printf("%s "，a)； //
Output symbol sequence
a
Characters in
Returns 0;
}
pay attention to
1, this method of getting strings can be preceded by a carriage return.
\n '
Attention! You can have a try. invest
When you press Enter in front and then enter a set of characters, the output is still the characters you output.
2. After trying to get into the car, run again, and then you add in front.
n
Spaces, and then enter a continuous.
Characters,
See what happens. You will find that he ignored all the spaces in front.
If you like,
Of course you can, or
Use regular expressions, or use
gets()；
For example:
Get (a);
In this way, the spaces you enter can also be recorded.
try again
Enter consecutive characters followed by a space, and then enter:
For example, enter someone's name.
When the word "
bill
Gates
"You will find that the output is only
bill
, and
Gates
So go to hell with the name input and input.
Noodles, too, are the best.
gets()；
Function.
(2)scanf("%c "，& ampa)； //
Pay attention to address symbols;
Example:
int main(){
char a；
scanf("%c "，& ampa)；
printf("%c "，a)； //
Output character
a
Characters in
Returns 0;
}
note:
If there is a carriage return when getting characters,
Absorb it.
You can try this,
Run the above program,
Get into the car once,
Looking closely, he left a few lines blank.
(You entered the first line, and the second line is
Print function
export
a
The value of)
Understand the mystery.
have you finished?
(3)
scanf("%d "，& ampa)；
example
int main(){
int a；
scanf("%d "，& ampa)；
printf("%d "，a)； //
Output shaping
a
Value in;
Returns 0;
}
Note: This input is the same as (
1
), the carriage return in front will be automatically ignored.
\n '(
It's actually a
American standard code for information interchange code
courtyard
)