📅  最后修改于: 2020-11-05 04:16:14             🧑  作者: Mango
飞镖编号可以归类为-
int-任意大小的整数。 int数据类型用于表示整数。
double -IEEE 754标准指定的64位(双精度)浮点数。 double数据类型用于表示小数
num类型由int和double类型继承。飞镖核心库允许对数值进行大量操作。
声明数字的语法如下-
int var_name; // declares an integer variable
double var_name; // declares a double variable
void main() {
// declare an integer
int num1 = 10;
// declare a double value
double num2 = 10.50;
// print the values
print(num1);
print(num2);
}
它将产生以下输出-
10
10.5
注意-如果将分数值分配给整数变量,则Dart VM将引发异常。
parse()静态函数允许将包含数字字面量的字符串解析为数字。下图演示了相同的内容-
void main() {
print(num.parse('12'));
print(num.parse('10.91'));
}
上面的代码将导致以下输出-
12
10.91
如果传递了数字以外的任何值,则解析函数将引发FormatException 。以下代码显示了如何将字母数字值传递给parse()函数。
void main() {
print(num.parse('12A'));
print(num.parse('AAAA'));
}
上面的代码将导致以下输出-
Unhandled exception:
FormatException: 12A
#0 num.parse (dart:core/num.dart:446)
#1 main (file:///D:/Demos/numbers.dart:4:13)
#2 _startIsolate. (dart:isolatepatch/isolate_patch.dart:261)
#3 _RawReceivePortImpl._handleMessage (dart:isolatepatch/isolate_patch.dart:148)
下表列出了Dart编号支持的属性。
Sr.No | Property & Description |
---|---|
1 | hashcode
Returns a hash code for a numerical value. |
2 | isFinite
True if the number is finite; otherwise, false. |
3 | isInfinite
True if the number is positive infinity or negative infinity; otherwise, false. |
4 | isNan
True if the number is the double Not-a-Number value; otherwise, false. |
5 | isNegative
True if the number is negative; otherwise, false. |
6 | sign
Returns minus one, zero or plus one depending on the sign and numerical value of the number. |
7 | isEven
Returns true if the number is an even number. |
8 | isOdd
Returns true if the number is an odd number. |
以下是数字支持的常用方法列表-
Sr.No | Method & Description |
---|---|
1 | abs
Returns the absolute value of the number. |
2 | ceil
Returns the least integer no smaller than the number. |
3 | compareTo
Compares this to other number. |
4 | Floor
Returns the greatest integer not greater than the current number. |
5 | remainder
Returns the truncated remainder after dividing the two numbers. |
6 | Round
Returns the integer closest to the current numbers. |
7 | toDouble
Returns the double equivalent of the number. |
8 | toInt
Returns the integer equivalent of the number. |
9 | toString
Returns the string equivalent representation of the number. |
10 | truncate
Returns an integer after discarding any fractional digits. |