1. Processing Method of CIN
1) if CIN reads an integer, it will automatically ignore line breaks and spaces. When the end mark is reached, the number returned by CIN> A is false.
Int;
While (CIN> ){
Cout <A <Endl;
}
Return 0;
Eg: 1, 2, 3
1 23
1 A2
A 12
Note: When CIN reads the 'A' character, if it is CIN> (INT); then CIN returns false, and the integer in variable A is 0; if it is \ n \ r, it is automatically ignored;
2) When CIN reads the string, \ n is used as the delimiter of the string.
String;
While (CIN> ){
Cout <;
}
Note: spaces are treated as delimiters and will not be stored in a. In addition, writing "\ n" in the standard input has no effect on line breaks, in this way, two characters are stored, and the keyboard's return key is used to store the "\ n" character.
3) CIN reads the string char *
After reading, \ n is automatically converted to \ 0
4) if the file ends, false is returned.
2. scanf Processing Method
Understanding of standard input: by default, scanf reads characters from the standard input and converts the characters accordingly. If it is a space or line feed, it will be skipped directly. If it does not meet the formatting requirements, therefore, scanf does not process nor reduce the information in the buffer.
1) read INTEGER:
Int A = 12;
While (scanf ("% d", & )! = EOF ){
Cout <A <Endl;
}
So, if we enter 'A', it will be in an endless loop.
2) read integer scanf ("% d, % d", & A, & B) is feasible; but read string scanf ("% s, % s ") is not feasible
Understanding of the input process: the input process consists of two parts. The first part needs to be sent to the keyboard buffer, Which is buffered by line;
The second process is to read data from the buffer to the corresponding memory space according to the formatting requirements;
3) hybrid input
Int A = 12, B = 12;
Char c = 'C ';
Cout <scanf ("% d % C", & A, & B, & C );
If we enter "123 A1", the input fields 1, B, and C are not assigned values. That is to say, scanf cannot ensure that all subsequent parameters are correctly assigned values.
3. fgets Processing Method
First, both gets and fgets can handle string input problems, and both can enter spaces. The difference is that fgets does not convert \ n to \ 0.
Principles of standard input: CIN and scanf
