Go language Learning (ii) constants

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 PackageMainImport "FMT"//1. Keyword const for defining constantsConstPifloat64=3.14159265358979323846ConstZero =0.0 //No type floating-point constantConst(SizeInt64=1024x768EOF =-1  //non-type integral constant)ConstU,vfloat32=0,3 multiple assignments of//u=0.0,v=3.0 constantsConstA, b, C =3,4,"foo" //a=3,b=4,c= "foo" untyped integral type and character constants//Go's constant definition can qualify a constant type, but is not required. If you define a constant without specifying a type, it//As with literal constants, there is no type constant. the right value of the//constant definition can also be a constant expression that is evaluated at compile time, such asConstMask =1<<3//2. Pre-defined constantsThe //go language is reserved for these constants: True,false and Iota//iota is a special, can be considered a compiler can be modified by a constant, when each const keyword appears to be reset to 0, and then the next const constant appears before the occurrence of a iota, each time it represents the number will be increased by 1Const(//iota is reset to 0C01 =Iota  //C01 = = 0C02 =Iota  //C02 = = 1C03 =Iota  //C03 = = 2)Const(//iota is reset to 0a0 =1<<Iota //a0 = = 1 (1 times 2 of 0 power)B1 =1<<Iota //B1 = = 2 (1 times 2 of 1 power)C1 =1<<Iota //C1 = = 4 (1 times 2 of 2 power))Const(//iota is reset to 0u1 =Iota* the //u1 = = 0V1float64=Iota* the //v1 ==42.0W1 =Iota* the //W1 ==84)ConstX1 =Iota //x1==0 because Iota was reset to 0.ConstY1 =Iota //y1==0 Ibid .//If the expression of the two Const assignment statement is the same, then the latter assignment expression can be omitted. Therefore, onthe first two const statements of//polygons can be abbreviated as:Const(C00 =IotaC11 C22)Const(A12 =1<<Iota //a12==1 (iota at each const start is reset to 0)B12//b12==2C12//c12==4)funcMain () {//Note: The declaration of a constant cannot be repeatedFmt. Println ("pi=", Pi) fmt. Println ("zero=", zero) fmt. Println ("Size=", size) fmt. Println ("eof=", EOF) FMT. Printf ("u=%v,v=%v\n", U,v) fmt. Printf ("a=%v,b=%v,c=%v\n", A,b,c) fmt. Printf ("c01=%v,c02=%v,c03=%v\n", C01,C02,C03) fmt. Printf ("a0=%v,b1=%v,c1=%v\n", A0,B1,C1) fmt. Printf ("u1=%v,v1=%v,w1=%v\n", U1,V1,W1) fmt. Printf ("x1=%v,y1=%v\n", X1,y1) fmt. Printf ("c00=%v,c11=%v,c22=%v\n", C00,C11,C22) fmt. Printf ("a12=%v,b12=%v,c12=%v\n", A12,B12,C12)}

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