Arrays in Scala are generally immutable, so we need to create a new array that will store the concatenated array in Scala. Or another method could be creating mutable arrays that will save memory. For merging two arrays Scala provides you multiple methods and we will discuss them one by one...
在Scala中,把哈希表这种数据结构叫做映射 1. 构建映射 2. 获取和修改映射中的值 好用的getOrElse 注意:在Scala中,有两种Map,一个是immutable包下的Map,该Map中的内容不可变;另一个是mutable包下的Map,该Map中的内容可变 例子: 注意:通常我们在创建一个集合是会用val这个... ...
Using Arrays in Python and Beyond Manipulate Arrays as Mutable Sequences Convert Between Arrays and Other Types Treat Arrays as Bytes-Like Objects Measuring the Performance of Python Arrays Emulating Nonstandard Numeric Types Understand Common Numeric Types Interpret Signed Integers of Any Size Conclusio...
you can no longer add or remove any elemetns. You can, however, change the values of elements in the array. This is in contrast to a vector array, which is a mutable array, in which elements can be added or removed
for(id obj in oldArray) { [newArray addObject: obj]; } NSLog(@"newArray:%@", newArray); //Deep copy NSMutableArray *newArray = [[NSMutableArray alloc] init]; NSArray *oldArray = [NSArray arrayWithObjects: @"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",nil]; ...
使用谓词过滤集合...- NSArray提供了如下方法使用谓词来过滤集合 `- (NSArray *)filteredArrayUsingPredicate:(NSPredicate *)predicate:`使用指定的谓词过滤...*)predicate:`使用指定的谓词过滤NSMutableArray,剔除集合中不符合条件的元素 - NSSet提供了如下方法使用谓词来过滤集合 `- (NSSet *)filteredSetUsing...
When the destination array’s element type is a class or an@objcprotocol, bridging fromNSArraytoArrayfirst calls thecopy(with:)(- copyWithZone:in Objective-C) method on the array to get an immutable copy and then performs additional Swift bookkeeping work that takes O(1) time. For instan...
copy 与 mutableCopy (1) 方法简介 拷贝方法 : -- copy 方法 : 复制对象的副本, 一般返回对象可修改的副本;假如被复制的对象是可修改 NSMutableString, 复制后成为NSString 不可修改; -- mutable 复制对象的可变副本, 返回对象的可变副本; 假如被复制对象不可修改 如 NSString, 使用...
data = bytes(b"abc") for value in data: print(value) print() # Create bytearray from byte literal. arr = bytearray(b"abc") for value in arr: print(value) 97 98 99 97 98 99 Slice, bytearray. We can slice bytearrays. And because bytearray is mutable, we can use slices to ch...
NSDictionary和NSMutableDictionary—字典,其条目储存为键-值对;键是唯一的标识符,通常为字符串,而值则是您要储存的对象。通过指定键,您可以访问该对象。 数组 数组(NSArray) 用于表示有序的对象列表。只要求每个项目都是 Objective-C 对象;不要求每个对象都是同一个类的实例。