chapter 14 stream input and output by c. shing itec dept radford university
Post on 03-Jan-2016
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Slide 2
Objectives Understand how to use unformatted input (cin)
and output (cout) Understand how to use formatted input (cin)
and output (cout)
Slide 4
Unformatted Input Use stream extraction (>>)
Input a character
char c;
cin >> c; Input a string
char string[SIZE];
cin >> string;
Slide 6
Unformatted Input (Cont.) Use cin member function
Input a characterchar c=cin.get();
Input a linechar line[80];
cin.getline(line, 80); Input a string
char string[SIZE];cin.get(string, SIZE); or cin.read(string, SIZE);
Slide 7
Unformatted Input (Cont.)Other related cin member functions:
1. cin.eof(): returns 0 if not reach EOF. Returns 1 otherwise.
2. cin.ignore(n, c): ignore n characters until the character c
3. cin.putback(c): put the character c back to reading stream
4. cin.peek(): peek the next charcter in the reading stream
5. cin.gcount(): return # of characters last read
Slide 9
Unformatted Output Use stream insertion (<<)
Ouput a character
char c;
cout << c; Output a string
char string[SIZE];
cout << string;
Slide 10
Unformatted Output (Cont.) Use stream insertion (<<) (Cont.)
Ouput string address (by casting to type void *)
char string[SIZE];
cout << “string address is “
<< static_cast<void *>string; Ouput variable address
cout << “number address is “
<< &number;
Slide 11
Unformatted Output (Cont.) Use cout member function
Output a character
char c=cout.put(); Output 2 characters
char c1, c2
cout.put(c1).put(c2); Output a string
char string[SIZE];
cout.write(string, SIZE); or
cout.write(string, cin.gcount());
Slide 13
Formatted Input/Output Include stream manipulator:
#include <iomanip> Can use either parametrized stream manipulator
or member functions
Slide 14
Formatted Input
Manipulator Member function
Explain
setw(n) cin.width(n) use n characters to read
Slide 16
Formatted Output
Manipulator Member function Explain
setbase(n)/dec/oct/hex
n=10(decimal),8(octal),16(hexadecimal)
setw(n) cout.width(n) n-1 characters to read
setprecision(n) cout.precision(n) n places after decimal point
setfill(c) cout.fill(c) Pad blank with character c
Slide 17
Formatted Output (Cont.)
Manipulator Member function Explain
setiosflags(flag)/setf(flag),resetiosflags(flag)/unsetf(flag)
cout.setf(flag), cout.unsetf(flag)
Set, reset stream format state
flags(flag)/flags() cout.flags(flag)/cout.flag()
Set format flag and return the previous format/show current format flag
Slide 18
ios Class Flags
Format state flag Explain
ios::skipws Skip white space on input stream
ios::left/ios::right Left/right justified
ios::internal Left justify sign, right justify number
ios::showbase Specify base
Slide 19
ios Class Flags (Cont.)
Format state flag Explain
ios::dec/ios::oct/ios::hex
Show values in base 10/8/16
ios::showpoint Show decimal point
ios::showpos Show signs
ios::scientific Show scientific notation
Slide 20
ios Class Flags (Cont.)
Format state flag Explain
ios::uppercase Show uppercase for letters of output
ios::fixed Show fixed floating point
ios::showpos Show signs
ios::scientific Show scientific notation
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