Stream manipulator showpoint is a sticky setting that forces a floating-point number to be output with its decimal point and trailing zeros. For example, the floating-point value 79.0
prints as 79
without using showpoint
and prints as 79.000000
(or as many trailing zeros as are specified by the current precision) using showpoint
. To reset the showpoint
setting, output the stream manipulator noshowpoint. The program in Fig. 13.13 shows how to use stream manipulator showpoint
to control the printing of trailing zeros and decimal points for floating-point values. Recall that the default precision of a floating-point number is 6. When neither the fixed
nor the scientific
stream manipulator is used, the precision represents the number of significant digits to display (i.e., the total number of digits to display), not the number of digits to display after decimal point.
1 // Fig. 13.13: fig13_13.cpp
2 // Controlling the printing of trailing zeros and
3 // decimal points in floating-point values.
4 #include <iostream>
5 using namespace std;
6
7 int main()
8 {
9 // display double values with default stream format
10 cout << "Before using showpoint" << endl
11 << "9.9900 prints as: " << 9.9900 << endl
12 << "9.9000 prints as: " << 9.9000 << endl
13 << "9.0000 prints as: " << 9.0000 << endl << endl;
14
15 // display double value after showpoint
16 cout << showpoint
17 << "After using showpoint" << endl
18 << "9.9900 prints as: " << 9.9900 << endl
19 << "9.9000 prints as: " << 9.9000 << endl
20 << "9.0000 prints as: " << 9.0000 << endl;
21 } // end main
Before using showpoint
9.9900 prints as: 9.99
9.9000 prints as: 9.9
9.0000 prints as: 9
After using showpoint
9.9900 prints as: 9.99000
9.9000 prints as: 9.90000
9.0000 prints as: 9.00000
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