Operators
There are six operators in dart:
- arithmetic
- relational
- check type
- bitwise
- assignment
- logical
- conditional
1. Arithmetic
The arithmetic operators are the same as the java, but the ~/ is an exception in dart.
| 1 | 2 | 3 |
|---|---|---|
+ |
- |
* |
/ |
~/ divide but return integer |
-expr reverse the sign |
% |
++ |
-- |
var a = 3 ~/ 2;
print(a); //print 1
a = -a;
print(a); //print -1
2. relational
Same as the java.
| 1 | 2 | 3 |
|---|---|---|
> |
< |
>= |
<= |
== |
!= |
var a = 1;
var b = 2;
var isLarge = a > b;
var isLow = a < b;
print(isLarge); //print false means that a is not larger than b.
print(isLow); // print true means that a is lower than b.
3. check type
| 1 | 2 |
|---|---|
is |
is! |
| check the variable is or not the appoint type | the reverse ,check is not |
var a = 1;
var isInt = a is int;
var isDouble = a is! double;
print(isInt); //print true.
print(isDouble); //print true.
4. bitwise
All the bitwise operators are operating with its responsive place.
| operator | description | example |
|---|---|---|
&AND |
a & b | if its responsive bits are same as 1 then take the one,otherwise zero. |
| OR | the sign is a Vertical line | if have an one ,take one |
^ XOR |
a^b | if different take one ,otherwise take zero |
~ NOT |
~a | this one is very special , the ~1 == -2 just invert the a |
<< left shift |
a«b | the bits of a shift left b step. |
>> right shift |
a » b | the bits of a shift right b step |
If you understand the the ~ operator very different , if can look at these Answers and Complement.
5. assignment
There some common operators about assignment operator, such as +=.
| operator | explanation |
|---|---|
= |
var a = 12; //just a sample assign |
??= |
if variable is null then assign it |
+= |
a +=1 means a =a+1,the other multi assignment is the same use |
-=,*=,/= |
the using is the same as the += but have the different operators |
6. Logical
there are three operators in logical operators.
| operator | explanation |
|---|---|
&& |
both true will return true. |
vertical line OR |
can not show the vertical line here. if have true return true. |
! |
invert variable ,if true return false |
7. Conditional
This is same as the ?: expression in java. The mean is that if true return a else return b.
var a = !true;
var content = a ? "this is true" : "this is false.";
print(content); //will print 'this is false.'
Loop
There are two types of loop,the keywords are for and while .But for have two sub types and while also have two sub types.examples following:
var names = ["xiaoming", "xiaoqiang", "laowang"];
print("for example:");
for (var i = 0; i < names.length; i++) {
print("name$i: ${names[i]}");
}
print("for in example:");
for (var name in names) {
print(name);
}
print("while example:");
var index = 0;
while (index < names.length) {
print(names[index]);
index++;
}
print("do while example:");
index = 0;
do {
print(names[index]);
index++;
} while (index < names.length);
Decision Making
In every programming language,there must be a decision sentence,so as the dart,the using is almost same as the java.The keyword is if,switch,examples are below.
var a = 1;
if (a == 2) {
print("a==2");
} else if (a is double) {
print("a is double type");
} else if (a == 1) {
print("a = 1");
}else{
print("I don't know what is the a");
}
switch (a) {
case 2:
print("a==2");
break;
case 1:
print("a==1");
break;
default:
print("I do not know what is the a");
break;
}
The decision is easy to use it.I expect you can use it by yourself.
The End.