"Go Learning Notes" 8, map

This is a creation in Article, where the information may have evolved or changed.

Map

• Similar to a hash table or dictionary in other languages, storing data in key-value form
• Key must be a type that supports the = = or! = comparison operation and cannot be a function, map, or slice
• Map lookup is much faster than linear search, but 100 times times slower than using indexed access data

• Map using make () to create, support: = This shorthand method

• Map ([Keytype]valuetype,cap), cap represents capacity, can be omitted

• Capacity is automatically expanded when exceeded, but as much as possible to provide a reasonable initial value

• Use Len () to get the number of elements

• A key-value pair is added automatically when it does not exist, and a key-value pair is deleted using Delete ()

• Use for range to iterate over map and slice

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//k int v stringvarMaptmpMap[int]stringMaptmp = Make(Map[int]string) maptmp[1] ="Hundredlee"Fmt. Println (MAPTMP)//k int v mapvarMaptmpMap[int]Map[int]stringMaptmp = Make(Map[int]Map[int]string) _, OK: = maptmp[0][0]if!ok {maptmp[0] = Make(Map[int]string)}fmt. Println (MAPTMP)//Slice v map + iteratorSlicemap: = Make([]Map[int]string,5) forI: =RangeSlicemap {Slicemap[i] = Make(Map[int]string) slicemap[i][1] ="OK"}fmt. Println (Slicemap)