Php to operation of arithmetic operators (integer, float, string, Boolean, null type) data

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 . 3  // PHP version
 . 4  // the PHP + 7.0.33-0 deb9u1 (CLI) (Built: On Dec 2018 11:36:49. 7) (the NTS)
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 12  // date: 2019-07-03T13: 20: 56.241Z
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17 // OS: Linux x64 4.15.0-30deepin-generic

 

1. (positive and negative) and integer (positive or negative) obtained by adding an integer (positive or negative) integers.

1 $a = 1;
2 $b = 1;
3 var_dump( $a + $b );
4 $a = 1;
5 $b = -2;
6 var_dump( $a + $b );
7 // int(2)
8 // int(-1)

 

2. (positive and negative) and float (positive and negative) are added to give float (positive and negative) float, as a result (positive or negative) integer, the output (positive or negative) integers, but still to a float type type.

1 $a = 1.0;
2 $b = 1.0;
3 var_dump( $a + $b );
4 $a = 1.0;
5 $b = -2.0;
6 var_dump( $a + $b );
7 // float(2)
8 // float(-1)

 

3. two string type (positive or negative) integer addition, as a result (positive or negative) integers.

1 $a = '1';
2 $b = '1';
3 var_dump( $a + $b );
4 $a = '1';
5 $b = '-2';
6 var_dump( $a + $b );
7 // int(2)
8 // int(-1)

 

4. The two string type (positive and negative) floating-point addition, as a result (positive or negative) integer, the output (positive or negative) integers, but still floating point type.

1 $a = '1.0';
2 $b = '1.0';
3 var_dump( $a + $b );
4 $a = '1.0';
5 $b = '-2.0';
6 var_dump( $a + $b );
7 // float(2)
8 // float(-1)

 

The two sequences are added character string, the result is an integer 0.

1 $a = 'y';
2 $b = 'j';
3 var_dump( $a + $b );
4 $a = 'true';
5 $b = 'null';
6 var_dump( $a + $b );
7 // int(0)
8 // int(0)

 

6. two Boolean addition: Boolean True Gabr really integer type 2, type false boolean false Gabr have integer 0, plus a Boolean sum to obtain a true integer 1.

 1 $a = true;
 2 $b = true;
 3 var_dump( $a + $b );
 4 $a = false;
 5 $b = false;
 6 var_dump( $a + $b );
 7 $a = true;
 8 $b = false;
 9 var_dump( $a + $b );
10 // int(2)
11 // int(0)
12 // int(1)

7. The two types of null space obtained by adding the integer 0.

1 $a = null;
2 $b = null;
3 var_dump( $a + $b );
4 // int(0)

 

8. (positive and negative) and float (positive or negative) obtained by adding an integer (positive or negative) float, as a result (positive or negative) integer, the output (positive or negative) integers, but still floating point type .

1 $a = 1.0;
2 $b = 1;
3 var_dump( $a + $b );
4 $a = 1.0;
5 $b = -2;
6 var_dump( $a + $b );
7 // float(2)
8 // float(-1)

 

9. The string (positive and negative) and floating-point character (positive or negative) integer addition, as a result (positive or negative) integer, the output (positive or negative) integers, but still floating point type.

1 $a = '1.0';
2 $b = '1';
3 var_dump( $a + $b );
4 $a = '1.0';
5 $b = '-2';
6 var_dump( $a + $b );
7 // float(2)
8 // float(-1)

 

Less -

Take *

In addition to /

Mode%

power**

 

Conjecture: The above five different operators in addition to mathematical rules, consistent with the above-described plus.