[Zz] usage of functions such as Cin, Cin. Get (), Cin. Getline (), Getline (), and gets ()

Usage of functions such as Cin, Cin. Get (), Cin. Getline (), Getline (), and gets ()

When I was learning C ++, these input functions were a bit confusing. Here I will make a summary. I hope it will be helpful for later users to review them, if there are any errors, please kindly advise (all in this articleProgramAll run through VC 6.0) reprinted, please keep the author information;
1. Cin
1. Cin. Get ()
2. Cin. Getline ()
3. Getline ()
4. Gets ()
5. getchar ()

1. Cin>

Usage 1: the most basic and common usage. Enter a number:

# Include <iostream>
Using namespace STD;
Main ()
{
Int A, B;
Cin> A> B;
Cout <a + B <Endl;
}

Input: 2 [Press enter] 3 [Press enter]
Output: 5

Usage 2: accept a string. When "space", "tab", and "Press ENTER" are all completed

# Include <iostream>
Using namespace STD;
Main ()
{
Char A [20];
Cin>;
Cout <A <Endl;
}

Input: jkljkljkl
Output: jkljkljkl

Input: jkljkl// Ends with a space
Output: jkljkl

2. Cin. Get ()

Usage 1: cin. Get (character variable name) can be used to receive characters

# Include <iostream>
Using namespace STD;
Main ()
{
Char ch;
Ch = cin. Get (); // or CIN. Get (CH );
Cout <ch <Endl;
}

Input: jljkljkl
Output: J

Usage 2: cin. Get (character array name, number of characters received) is used to receive a line of string, can receive Spaces

# Include <iostream>
Using namespace STD;
Main ()
{
Char A [20];
Cin. Get (A, 20 );
Cout <A <Endl;
}

Input: jkl
Output: jkl

Input: abcdeabcdeabcdeabcdeabcde (25 characters)
Output: abcdeabcdeabcdeabcd (receiving 19 characters + 1 '\ 0 ')

3. Cin. Getline () // receives a string and can receive spaces and Output

Getline replaces the linefeed with a null character.

# Include <iostream>
Using namespace STD;
Main ()
{
Char M [20];
Cin. Getline (M, 5 );
Cout <m <Endl;
}

Input: jkljkljkl
Output: jklj

Accept 5 characters to m, and the last one is '\ 0'. Therefore, only 4 characters of output are displayed;

If you change 5 to 20:
Input: jkljkljkl
Output: jkljkljkl

Input: jklf fjlsjf fjsdklf
Output: jklf fjlsjf fjsdklf

// Extension:
// Cin. Getline () actually has three parameters: cin. Getline (accept the string to see the M, accept the number of 5, end character)
// When the third parameter is omitted, the default value is '\ 0'
// If you change cin. Getline () in the example to CIN. Getline (M, 5, 'A'), and output jklj when jlkjkljkl is input, output JK when jkaljkljkl is input.

When using multi-dimensional arrays, you can also use cin. Getline (M [I], 20) or the like:

# Include <iostream>
# Include <string>
Using namespace STD;

Main ()
{
Char M [3] [20];
For (INT I = 0; I <3; I ++)
{
Cout <"\ n enter the" <I + 1 <"string:" <Endl;
Cin. Getline (M [I], 20 );
}

Cout <Endl;
For (Int J = 0; j <3; j ++)
Cout <"output M [" <j <"] value:" <m [J] <Endl;

}

Enter 1st strings:
Kskr1

Enter 2nd strings:
Kskr2

Enter 3rd strings:
Kskr3

Output M [0] value: kskr1
Output M [1] value: kskr2
Output M [2] value: kskr3

4. Getline () // accepts a string.To receive and output spaces,Must contain "# include <string>"

# Include <iostream>
# Include <string>
Using namespace STD;
Main ()
{
String STR;
Getline (CIN, STR );
Cout <STR <Endl;
}

Input: jkljkljkl
Output: jkljkljkl

Input: jkl jfksldfj jklsjfl
Output: jkl jfksldfj jklsjfl

Similar to CIN. Getline (), but cin. Getline () belongs to the istream stream, while Getline () belongs to the string stream. It is a different function.

5. Gets () // receives a string, receives spaces, and outputs the string. It must contain "# include <string>"

# Include <iostream>
# Include <string>
Using namespace STD;
Main ()
{
Char M [20];
Gets (m); // cannot be written as M = gets ();
Cout <m <Endl;
}

Input: jkljkljkl
Output: jkljkljkl

Input: jkl
Output: jkl

Similar to an example in CIN. Getline (), gets () can also be used in multi-dimensional arrays:

# Include <iostream>
# Include <string>
Using namespace STD;

Main ()
{
Char M [3] [20];
For (INT I = 0; I <3; I ++)
{
Cout <"\ n enter the" <I + 1 <"string:" <Endl;
Gets (M [I]);
}

Cout <Endl;
For (Int J = 0; j <3; j ++)
Cout <"output M [" <j <"] value:" <m [J] <Endl;

}

Enter 1st strings:
Kskr1

Enter 2nd strings:
Kskr2

Enter 3rd strings:
Kskr3

Output M [0] value: kskr1
Output M [1] value: kskr2
Output M [2] value: kskr3

The usage of gets () and CIN. Getline () is similar, except that CIN. Getline () has one more parameter;

Here, the kskr1, kskr2, and kskr3 examples in this article can also be used for CIN>, because the input here is not empty.
If a space is entered, for example, "Ks KR jkl [Press enter]", CIN will have received three strings, "Ks, KR, jkl", and then "kskr ".
1 [Press enter] kskr
2 [Press enter], then "kskr, 1, kskr" is received; this is not the result we want! Cin. Getline () and gets () do not generate because they can receive spaces.
This error is generated;

6. getchar () // accepts one character, which must contain"# Include <string>"

# Include <iostream>
# Include <string>
Using namespace STD;
Main ()
{
Char ch;
Ch = getchar (); // cannot be written as getchar (CH );
Cout <ch <Endl;
}

Input: jkljkljkl
Output: J

// Getchar () is a C-language function, which can be compatible with C ++, but is not required or used as little as possible;