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Outline (continued)
21.6 Stream Manipulators
21.6.1 Integral Stream Base: dec , oct , hex and setbase
21.6.2 Floating-Point Precision ( precision , setprecision )
21.6.3 Field Width ( setw , width )
21.6.4 User-Defined Manipulators
21.7 Stream Format States
21.7.1 Format State Flags
21.7.2 Trailing Zeros and Decimal Points ( ios::showpoint )
21.7.3 Justification ( ios::left , ios::right , ios::internal )
21.7.4 Padding ( fill , setfill )
21.7.5 Integral Stream Base ( ios::dec , ios::oct , ios::hex ,
ios::showbase )
21.7.6 Floating-Point Numbers; Scientific Notation
( ios::scientific , ios::fixed )
21.7.7 Uppercase/Lowercase Control ( ios::uppercase )
21.7.8 Setting and Resetting the Format Flags ( flags ,
setiosflags , resetiosflags )
21.8 Stream Error States
21.9 Tying an Output Stream to an Input Stream
Chapter 21 - C++ Stream Input/Output Stream
Manipulators
21.6 Stream Manipulators
- Stream manipulator capabilities
- Setting field widths
- Setting precisions
- Setting and unsetting format flags
- Setting the fill character in fields
- Flushing streams
- Inserting a newline in the output stream and flushing the stream
- Inserting a null character in the output stream and skipping
whitespace in the input stream
1. Load header
1.1 Initialize variables
2. Input number
3. Output in hex
3.1 Output in octal
3.2 Output in decimal
1 // Fig. 21.16: fig21_16.cpp 2 // Using hex, oct, dec and setbase stream manipulators. 3 #include 4 5 using std::cout; 6 using std::cin; 7 using std::endl; 8 9 #include
10
11 using std::hex;
12 using std::dec;
13 using std::oct;
14 using std::setbase;
15
16 int main()
17 {
18 int n;
19
20 cout << "Enter a decimal number: ";
21 cin >> n;
22
23 cout << n << " in hexadecimal is: "
24 << hex << n << '\n'
25 << dec << n << " in octal is: "
26 << oct << n << '\n'
27 << setbase( 10 ) << n << " in decimal is: "
28 << n << endl;
29
30 return 0;
31 }
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Program Output
- Enter a decimal number:
- 20 in hexadecimal is:
- 20 in octal is:
- 20 in decimal is:
21.6.3 Field Width (setw,width)
- ios width member function
- Sets field width (number of character positions a value should be
output or number of characters that should be input)
- Returns previous width
- If values processed are smaller than width, fill characters inserted
as padding
- Values are not truncated - full number printed
- cin.width(5);
- setw stream manipulator
cin >> setw(5) >> string;
- Remember to reserve one space for the null
character
1. Initialize variables
2. Input sentence
2.1 Set width
2.2 Loop and change
width
3. Output
1 // fig21_18.cpp
2 // Demonstrating the width member function
3 #include
4
5 using std::cout;
6 using std::cin;
7 using std::endl;
8
9 int main()
10 {
11 int w = 4;
12 char string[ 10 ];
13
14 cout << "Enter a sentence:\n";
15 cin.width( 5 );
16
17 while ( cin >> string ) {
18 cout.width( w++ );
19 cout << string << endl;
20 cin.width( 5 );
21 }
22
23 return 0;
24 } Docsity.com
21.6.4 User-Defined Manipulators
- We can create our own stream manipulators
- bell
- ret (carriage return)
- tab
- endLine
- Parameterized stream manipulators
- Consult installation manuals
21.7 Stream Format States
- Format flags
- Specify formatting to be performed during stream I/O operations
- setf, unsetf and flags
- Member functions that control the flag settings
21.7.2 Trailing Zeros and Decimal Points
( ios::showpoint )
- ios::showpoint
- Forces a float with an integer value to be printed with its decimal
point and trailing zeros
cout.setf(ios::showpoint)
cout << 79;
79 will print as 79.
- Number of zeros determined by precision settings
21.7.3 Justification ( ios::left, ios::right,
ios::internal )
- ios::left
- Fields to left-justified with padding characters to the right
- ios::right
- Default setting
- Fields right-justified with padding characters to the left
- Character used for padding set by
- fill member function
- setfill parameterized stream manipulator
- Default character is space
1. Initialize variable
2. Use parameterized
stream manipulators
3. Output
1 // Fig. 21.22: fig21_22.cpp 2 // Left-justification and right-justification. 3 #include 4 5 using std::cout; 6 using std::endl; 7 8 #include 9
10 using std::ios;
11 using std::setw;
12 using std::setiosflags;
13 using std::resetiosflags;
14
15 int main() 16 {
17 int x = 12345;
18
19 cout << "Default is right justified:\n"
20 << setw(10) << x << "\n\nUSING MEMBER FUNCTIONS"
21 << "\nUse setf to set ios::left:\n" << setw(10);
22
23 cout.setf( ios::left, ios::adjustfield ); 24 cout << x << "\nUse unsetf to restore default:\n";
25 cout.unsetf( ios::left );
26 cout << setw( 10 ) << x
27 << "\n\nUSING PARAMETERIZED STREAM MANIPULATORS"
28 << "\nUse setiosflags to set ios::left:\n"
29 << setw( 10 ) << setiosflags( ios::left ) << x
30 << "\nUse resetiosflags to restore default:\n"
31 << setw( 10 ) << resetiosflags( ios::left )
32 << x << endl; 33 return 0;
34 }
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Program Output
Default is right justified: 12345
USING MEMBER FUNCTIONS
Use setf to set ios::left: 12345 Use unsetf to restore default: 12345
USING PARAMETERIZED STREAM MANIPULATORS
Use setiosflags to set ios::left: 12345 Use resetiosflags to restore default: 12345
1. Load header
1.1 Initialize variable
1 // Fig. 21.24: fig21_24.cpp
2 // Using the fill member function and the setfill
3 // manipulator to change the padding character for
4 // fields larger than the values being printed.
5 #include
6
7 using std::cout;
8 using std::endl;
9
10 #include
11
12 using std::ios;
13 using std::setw;
14 using std::hex;
15 using std::dec;
16 using std::setfill;
17
18 int main()
19 {
20 int x = 10000; Docsity.com
2. Set fill character
3. Output
Program Output
22 cout << x << " printed as int right and left justified\n"
23 << "and as hex with internal justification.\n"
24 << "Using the default pad character (space):\n";
25 cout.setf( ios::showbase );
26 cout << setw( 10 ) << x << '\n';
27 cout.setf( ios::left, ios::adjustfield );
28 cout << setw( 10 ) << x << '\n';
29 cout.setf( ios::internal, ios::adjustfield );
30 cout << setw( 10 ) << hex << x;
31
32 cout << "\n\nUsing various padding characters:\n";
33 cout.setf( ios::right, ios::adjustfield );
34 cout.fill( '*' );
35 cout << setw( 10 ) << dec << x << '\n';
36 cout.setf( ios::left, ios::adjustfield );
37 cout << setw( 10 ) << setfill( '%' ) << x << '\n';
38 cout.setf( ios::internal, ios::adjustfield );
39 cout << setw( 10 ) << setfill( '^' ) << hex << x << endl;
40 return 0;
41 }
10000 printed as int right and left justified and as hex with internal justification. Using the default pad character (space): 10000 10000 0x 2710
Using various padding characters:
10000%%%%%
0x^^^^2710 Docsity.com
