String c = a ?? b;

源自：3-5 条件表达式

String c = a ?? b;

Warning: Operand of null-aware operation '??' has type 'String' which excludes null.

chapter3/operator_conditional.dart:17

String c = a ?? b;

我这里使用这String c = a?? b; 出现了警告，这是为什么啊？！

提问者：丛从绿草 2021-11-24 16:04

个回答

weixin_慕码人0066820

2022-12-09 14:10:05

String 类型改成 dynamic 动态的

0
weixin_慕丝9160112

2022-09-11 15:21:05

var b;

0
weixin_慕丝9160112

2022-09-11 15:17:59
```
b;
b ??= ;
```
0
慕UI6158054

2021-11-30 15:51:36
```
int a=5;
a ??= 10;
print(a);
```
Warning: Operand of null-aware operation '??=' has type 'int' which excludes null.
a ??= 10;
一样报错

0