## 1. Write in front

Introduced in the previous articleDartofwas,finalandconstgrammar and usage, then continue to learn nowDartThe basic grammar of it!

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## 2. Numeric type num

existdartlanguage, numeric typesnumberdivided into twointanddouble.

### 2.1 int type

void  main ( ) {

numTest();
}

void  numTest ( ) {
//number numeric int and double
num a =  1 ;
print ( a ) ;
}
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The results are as follows:

### 2.2 double type

void  numTest ( ) {
//number numeric int and double
num a =  1 ;
print ( a ) ;
a =  3.4 ;
print ( a ) ;
}
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The results are as follows:

Need noton onedeclaration, can be used directlyintanddoubleAlso can.

void  numTest ( ) {
//number numeric int and double
num a =  1 ;
print ( a ) ;
a =  3.4 ;
print ( a ) ;

int b = 4;
print(b);

double c = 3.3;
print(c);
}
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operation result:

doubleassignable typeintInteger,inttype is not assignabledouble.

### 2.3 Common methods

There are also some commonly used methods, such as judgmentodd numberstill iseven, subtraction, addition, multiplication and division (+ - * / ), modulo (%) and a special rounding (~/).

void  numTest ( ) {
//number numeric int and double
num a =  1 ;
print ( a ) ;
a =  3.4 ;
print ( a ) ;

int b = 4;
print(b);

double c =  3 ; //equivalent to 3.0
print ( c ) ;

print ( b . isEven ) ; // is even
print ( b . isOdd ) ; // is odd

print ( b ~ / c ) ; // round up

}
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The results are as follows:

### 2.4 Type conversion

isEvenis even,isOddOdd or not, this is onlyinttype can only be called, thendoubleIf you want to call the type, you need to convert the type.

inttypes can also be converted todoubleYes, types can be converted to each other.

## 3. Write at the back

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