C + + to solve the problem of data accuracy, floating point to save the location of decimal __c++

1. Background

To save a floating point number is to position a decimal.   For example, 1.123456. To save a 1-bit decimal, the method is invoked and the result saved is: 1.1. For example, 1.98765, the result of saving 2 decimal places is: 2.00.

2. Solution

A, add header file

#include <sstream>
#include <iomanip>

B, add namespaces

using namespace Std;

C, add a function

        /************************************************************************/
	/* Function name: round
	/* Function function: Data precision calculation function
	/* function parameter: float src: Refinement degree     int bits: precision (0 for 0 decimal places after the decimal point, 1 for reserved 1 decimal digits, 2 for reserved 2 decimal places)//
	function return value: Precision result/
	* Author:  Lee
	/************************************************************************/
	float round (float SRC, int bits);

function implementation

float Cdemo1dlg::round (float src, int bits)
{
	StringStream ss;
	SS << Fixed << setprecision (bits) << F;
	SS >> F;

	return f;

}

D, how to call

	CString str2 = L "99.054";
	float F2 = (float) _wtof (str2);
	F2 *=;
	F2 = This->round (F2, 2);

E, attention

For example, 1.05, double is represented in the computer as 1.0499999997, and float is represented as 1.0500000003, but it is actually equal to 1.05.

The round-side approach has an exception to the number of digits processed, such as: 1.05, which may result in 1.0499999997. Here is the float, you can switch to other types. I'll see how many times I have to test it.

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