dart double question mark
// This means a equals b, but if b is null then a equals 'hello'.
String a = b ?? 'hello';
// This means if b is null then set it equal to hello. Otherwise, don't change it.
b ??= 'hello';dart double question mark
// This means a equals b, but if b is null then a equals 'hello'.
String a = b ?? 'hello';
// This means if b is null then set it equal to hello. Otherwise, don't change it.
b ??= 'hello';dart double question mark
// This means a equals b, but if b is null then a equals 'hello'.
String a = b ?? 'hello';question mark in dart
// single question mark ? is used to guard access to a property or method of an object that might be null
childCount: snapshot.data?.length // here ? give you access to length that might be null
// if length is null, ?? => it will equal 0Copyright © 2021 Codeinu
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