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Working with Streams 623

17

For example,

cout << “\aAn error occured\t”

rings the bell, prints an error message, and moves to the next tab stop. Manipulators are

used with the cout operator. Those manipulators that take arguments require that you

include iomanip in your file.

The following is a list of manipulators that do notrequire iomanip:

flush—Flushes the output buffer

endl—Inserts newline and flushes the output buffer

oct—Sets output base to octal

dec—Sets output base to decimal

hex—Sets output base to hexadecimal

The following is a list of manipulators that do require iomanip:

setbase(base)—Sets output base (0 = decimal, 8 = octal, 10 = decimal, 16 = hex)

setw(width)—Sets minimum output field width

setfill(ch)—Fills character to be used when width is defined

setprecision(p)—Sets precision for floating-point numbers

setiosflags(f)—Sets one or more iosflags

resetiosflags(f)—Resets one or more iosflags

For example,

cout << setw(12) << setfill(‘#’) << hex << x << endl;

sets the field width to 12, sets the fill character to ‘#’, specifies hex output, prints the

value of ‘x’, puts a newline in the buffer, and flushes the buffer. All the manipulators

except flush, endl, and setwremain in effect until changed or until the end of the

program. setwreturns to the default after the current cout.

A number of flags can be used with the setiosflags and resetiosflags manipulators.

These were listed in Table 17.1 earlier.

Additional information can be obtained from file iosand from your compiler’s

documentation.

File Input and Output ..........................................................................................

Streams provide a uniform way of dealing with data coming from the keyboard or the

hard disk and going out to the console screen or hard disk. In either case, you can use the

insertion and extraction operators or the other related functions and manipulators. To