Dart and Flutter for loop multiple iterators

Question

I have a for loop in my Flutter project similar to this (simplified):

for(int i=0; i<aVariableDeclaredBefore; i++) Padding(....

Here I need another operation after i++ run as this one anotherVariable--. I can't do it in {} braces because loop used for Widget manipulation. There is no curly braces there.

I need something like this ((i++)&&(anotherVariable--)) but how ? if it is possible

Alternatively consider if you need anotherVariable at all. If you're always incrementing i and always decrementing anotherVariable, on each iteration you could derive the intended value for anotherVariable from i. — jamesdlin
– jamesdlin, Commented Jan 23, 2023 at 5:07

Chuck Batson · Accepted Answer · 2023-01-23 18:27:04Z

4

Use the comma ~~operator~~:

void main() {
  for (var i = 0, j = 10; i < 10; i++, j++) {
    print('i=$i, j=$j');
  }
}

Output:

i=0, j=10
i=1, j=11
i=2, j=12
i=3, j=13
i=4, j=14
i=5, j=15
i=6, j=16
i=7, j=17
i=8, j=18
i=9, j=19

edited Jan 23, 2023 at 18:27

answered Jan 22, 2023 at 21:28

Chuck Batson

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1 Comment

mezoni Over a year ago

You wrote: Use the comma operator. You're not right. The comma is not an operator. This is the expression separator in the list of expressions. You shouldn't mislead people. Dart does not and never will have the , operator.

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