Swift 2.0 Study Notes (Day 15)--note the conversion between numeric types

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in other languages such as C,objective-c , and Java , there are two ways to convert integers:

• From the small range number to the large range number conversion is automatic;

• Forcing type conversions from a large number to a small range can result in the loss of data precision.

and in Swift These two methods are not feasible and need to be explicitly converted through some functions, the code is as follows:

Let Historyscore:uint8 = 90

Let englishscore:uint16 = 130

Let totalscore = Historyscore + englishscore// Error

The program will have a compilation error becauseHistoryscoreis aUInt8type, andEnglishscoreis aUInt16types, which cannot be converted between them.

Two methods of conversion:

• one is to UInt8 of the Historyscore converted to UInt16 type. This conversion is safe because it is converted from a small range to a large range number.

Code:

Let totalscore = UInt16 (historyscore) + englishscore// is the correct method of conversion.

• The other is to UInt16 of the Englishscore converted to UInt8 type. Because it is converted from a large range to a small range number, this conversion is unsafe, and if the number of conversions is larger it can result in loss of precision.

Code:

Let totalscore = Historyscore + UInt8 (englishscore)// is the correct method of conversion.

in this example Englishscore The value is , this conversion is successful, if the number is changed to 1300, although the program compiles no problem, but the exception information is output in the console.

Conversion between integral type and floating point type

Conversions between integral and floating-point types are similar to conversions between integral types:

Let historyscore:float = 90.6　　　

Let englishscore:uint16 = 130　

Let totalscore = Historyscore + englishscore// Error

Let totalscore = Historyscore + Float (englishscore)// Right, safe

Let totalscore = UInt16 (historyscore) + englishscore// right, the decimals are cut off  

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Swift 2.0 Learning Note (Day 15)--note the conversion between numeric types