OC Array Application example-verification code

//Generate random verification code

1    //Nsmutablearray *marr = [[Nsmutablearray alloc]init]; //The following variables are used to enter the object in a variable immutable group, respectively2     3Nsarray *arrtest =[[Nsarray alloc]init];4     5      for(inti =0; I <Ten; i++)6     {7         //[Marr Addobject:[nsnumber numberwithint:i];8         9Arrtest =[Arrtest arraybyaddingobject:[nsnumber numberwithint:i];Ten     } One      A      for(inti ='a'; I <='Z'; i++) -     { -         //[Marr addobject:[nsstring stringwithformat:@ "%c", I]]; the          -Arrtest = [Arrtest arraybyaddingobject:[nsstring stringWithFormat:@"%c", I]]; -     } -      +      for(inti ='A'; I <='Z'; i++) -     { +        //[Marr addobject:[nsstring stringwithformat:@ "%c", I]]; A          atArrtest = [Arrtest arraybyaddingobject:[nsstring stringWithFormat:@"%c", I]]; -     } -    //NSLog (@ "%@", arrtest); -      -      -     //The second step produces a random digital output in     -  toNsmutablestring *mstr =[[nsmutablestring alloc]init]; +NSString *str =[[NSString alloc]init];; -      for(inti =0; I <4; i++) the     { *str = [arrtest objectatindex:arc4random ()%Arrtest.count]; $ [Mstr Appendstring:str];Panax Notoginseng          -  the       //str = [Marr objectatindex:arc4random ()% marr.count]; +          A       //MSTR = [Mstr stringbyappendingstring:str]; the          +       //[Mstr Appendstring:str]; -     } $NSLog (@"%@", MSTR); $      -      - [Arrtest release]; the     //[Marr release]; - [MSTR release];Wuyi [str release]; the    

------The first step , put all the numeric uppercase letters into an array ------

//[NSString stringWithFormat: Convert other types to objects

[Mutstr appendformat:<# (NSString *), ...#> infrequently used

variable array Increment object is AddObject: non-variable group splicing object is arraybyaddingobject:

//character types also need to be converted to Objects

//immutable type can be overwritten again

--------The second step to randomly remove an object from the array----------

//variable string:appendString No return value is to add a string to the original string

concatenation of two strings into an immutable string: Stringbyappendingstring is a return value

OC Array Application example-verification code