. Net (C #): It is not difficult to keep the valid number of floating point numbers as simple as C ++!

Note:

The output of C/C ++ may have different results under different compilers. If your compiler is different from mine, we recommend that you copy C/C ++ code and run it on your own compiler to view the results.

 

All the following C # code is compiled and run by Visual C #2010 Express.

The following C/C ++ code is compiled and run by Visual C ++ 2010 Express.

 

Floating Point Output of C ++: 6 Valid digits are reserved by default.

Code:

Double arr [4] = {123.4567, 12345670, 12.34567, 0.001234567 };

 

For (INT I = 0; I <4; I ++)

Cout <arr [I] <Endl;

Output:

123.457

1.23457e + 007

12.3457

0.00123457

 

C # float is 7 bits, and double is 15 bits. Refer to msdn: http://msdn.microsoft.com/zh-cn/library/dwhawy9k.aspx#GFormatString

Note that if you do not need any formatting symbols, the. NET output uses the "G" formatting character by default.

VaR arr = new double [] {123.4567, 12345670, 12.34567, 0.001234567 };

 

Foreach (var d in ARR)

Console. writeline (D. tostring ());

Output:

123.4567

12345670

12.34567

0.001234567

All numbers are output as they are.

 

The accuracy of the output stream can be set by keeping valid numbers in C ++. Of course, the setting accuracy is not limited to cout, it can be any ios_base. The ios_base.precision function can be used here. Or use the setprecision function in <iomanip>. They all achieve the same effect!

 

For example, retain four valid numbers.

Code:

Double arr [4] = {123.4567, 12345670, 12.34567, 0.001234567 };

 

Cout. Precision (4 );

For (INT I = 0; I <4; I ++)

Cout <arr [I] <Endl;

Output:

123.5

1.235e + 007

12.35

0.001235

 

If C # is used, the "G" precision indicates that the valid digits are retained.(I was surprised to find that many people did not know how to find "C # retain valid numbers" in the search engine, and there were a lot of things in csdn ...... Every day, people may be misled, or some people may think that C # is so troublesome to keep a valid number ......)

 

Retain four digits.

Code:

VaR arr = new double [] {123.4567, 12345670, 12.34567, 0.001234567 };

 

Foreach (var d in ARR)

Console. writeline (D. tostring ("G4 "));

Output:

123.5

1.235e + 07

12.35

0.001235