3v4l.org

run code in 300+ PHP versions simultaneously
<?php // #1 function test1(){ echo PHP_EOL.__function__ .":"; $a=1; echo (++$a)+(++$a); } test1(); // 5 // #2 function test2(){ echo PHP_EOL.__function__ .":"; $a=1; $b=&$a; echo (++$a)+(++$a); } test2(); // 6(5.1.1 - 5.6.24) or 5(hhvm, 7.0.0+) // #3 function test3(){ echo PHP_EOL.__function__ .":"; $a=1; $b=&$a; echo (++$a)+(++$a)+(++$a); } test3(); // 10(5.1.1 - 5.6.24) or 9(hhvm, 7.0.0+) // #4 function test4(){ echo PHP_EOL.__function__ .":"; $a=1; // $b=&$a; echo $a + $a++; } test4(); // 3 // #5 function test5(){ echo PHP_EOL.__function__ .":"; $a = 1; // $b = &$a; // echo @$a + $a++; // 2 echo $a + $a++; // 3 } test5(); // 3 // #6 function test6(){ echo PHP_EOL.__function__ .":"; $a = 1; echo $a + $a + $a++; } test6(); // 3 /* 从上面的结果来看,有以下三点必须知识: - ++$a 是自己加1,之后的都要加1;如果是指针引用,有些版本会导致 ++$a 的临时值为自身,让之前的计算结果也改变。 - $a++ 是自己不用增1的结果,但是这个操作符之后的都要加1,不管有没有指针引用。 - 编译器每一次都要把表达式组合成两元组:((($a++ + $a) + $a) + $a); 但是在 ($a + $a++) 的情况下,会改变顺序为 ($a++ + $a),所以 $a++ + $a 的结果是3. 最终版本(php v7.0)(`$a = 1; $b = &$a; echo ++$a + ++$a + $a;`) compiled vars: !0 = $a, !1 = $b line #* E I O op fetch ext return operands ------------------------------------------------------------------------------------- 2 0 E > ASSIGN !0, 1 3 1 ASSIGN_REF !1, !0 4 2 PRE_INC $4 !0 3 PRE_INC $5 !0 4 ADD ~6 $4, $5 5 ADD ~7 ~6, !0 6 ECHO ~7 5 7 ECHO !0 8 > RETURN 1 from: https://3v4l.org/fgLZO/vld#tabs 注意: > 不同的php 版本不同,导致的结果不同。我用 c++ 测试过,gcc 和 clang 的结果也不同(当然会有warning). 总结: - 目前hhvm和7.0.0+都不再会受到指针引用的影响。(受影响的版本 5.1.1 - 5.6.24) - `++a;++a`, clang 结果是6, gcc 结果是5 - 混写的写法:不易查错,不易 debug,全语言混乱 - 建议:所有自增全部用新行写 */ // four quiz function quiz() { echo PHP_EOL.__function__ .":"; $a=1; $b=&$a; echo ($a++)+(++$a); $a=1; $b=&$a; echo (++$a)+($a++); $a=1; //$b=&$a; echo (++$a)+($a++); $a=1; $b=&$a; echo (++$a)+(++$a); } quiz(); // answer: 4445(hvvm,7.0.0+) 4556(4.3.0 - 5.6.24) // Good points from above // #0.1 // $a = -1; // var_dump($a && true); // true // var_dump($a && false); // false // var_dump($a && -1); // true // #0.2 // $a + $a + $a + $a + $a // + is left-assoc, so it's grouped as // (((($a + $a) + $a) + $a) + $a) // #0.3 // $a + $a + $a + $a + $a // $a = $b = $c = $d = $e // = is right-assoc, so it's grouped as // ($a = ($b = ($c = ($d = $e))))

Here you find the average performance (time & memory) of each version. A grayed out version indicates it didn't complete successfully (based on exit-code).

VersionSystem time (s)User time (s)Memory (MiB)
8.5.00.0120.01019.91
8.4.150.0020.00014.05
8.4.140.0110.01017.45
8.4.130.0100.01017.63
8.4.120.0060.01322.30
8.4.110.0130.01122.45
8.4.100.0130.00718.60
8.4.90.0050.00518.86
8.4.80.0090.00218.85
8.4.70.0130.00718.73
8.4.60.0130.01019.16
8.4.50.0080.01218.59
8.4.40.0130.00624.01
8.4.30.0120.00622.51
8.4.20.0170.00317.39
8.4.10.0100.01019.52
8.3.280.0090.01118.36
8.3.270.0110.00816.44
8.3.260.0140.00616.66
8.3.250.0110.00818.81
8.3.240.0120.00717.02
8.3.230.0100.00916.57
8.3.220.0090.00619.11
8.3.210.0060.00216.84
8.3.200.0050.00716.52
8.3.190.0050.00317.28
8.3.180.0090.00819.02
8.3.170.0110.00418.46
8.3.160.0090.00917.42
8.3.150.0090.00618.92
8.3.140.0160.00320.80
8.3.130.0040.00418.61
8.3.120.0090.00018.82
8.3.110.0060.00320.94
8.3.100.0040.00416.54
8.3.90.0150.00026.77
8.3.80.0040.00418.30
8.3.70.0060.01216.75
8.3.60.0110.00318.55
8.3.50.0150.00522.91
8.3.40.0150.00018.70
8.3.30.0040.01518.68
8.3.20.0040.00421.95
8.3.10.0040.00423.65
8.3.00.0050.00319.85
8.2.290.0110.00620.72
8.2.280.0060.00918.25
8.2.270.0080.01118.29
8.2.260.0070.01116.70
8.2.250.0050.00318.41
8.2.240.0090.00018.68
8.2.230.0130.00722.58
8.2.220.0000.00724.06
8.2.210.0100.00726.77
8.2.200.0060.00316.63
8.2.190.0110.00416.63
8.2.180.0030.01318.41
8.2.170.0100.00722.96
8.2.160.0070.00720.13
8.2.150.0040.00424.18
8.2.140.0070.00024.66
8.2.130.0040.00422.13
8.2.120.0040.00426.35
8.2.110.0060.00322.16
8.2.100.0040.00818.09
8.2.90.0000.00819.21
8.2.80.0040.00417.97
8.2.70.0060.00317.63
8.2.60.0050.00318.03
8.2.50.0040.00419.25
8.2.40.0000.00822.19
8.2.30.0040.00419.39
8.2.20.0000.00817.75
8.2.10.0050.00217.96
8.2.00.0000.00818.00
8.1.330.0040.00421.91
8.1.320.0090.01017.70
8.1.310.0140.00016.79
8.1.300.0080.00819.97
8.1.290.0040.00430.84
8.1.280.0120.00325.92
8.1.270.0090.00023.79
8.1.260.0070.00028.09
8.1.250.0000.00728.09
8.1.240.0040.00422.14
8.1.230.0070.00419.54
8.1.220.0080.00017.76
8.1.210.0050.00318.77
8.1.200.0090.00017.23
8.1.190.0090.00017.22
8.1.180.0040.00418.10
8.1.170.0040.00418.42
8.1.160.0040.00422.10
8.1.150.0000.00720.84
8.1.140.0040.00419.59
8.1.130.0070.00017.59
8.1.120.0000.00717.30
8.1.110.0000.00817.39
8.1.100.0040.00417.45
8.1.90.0000.00817.38
8.1.80.0040.00417.41
8.1.70.0000.00717.42
8.1.60.0000.00817.65
8.1.50.0030.00517.61
8.1.40.0030.00517.45
8.1.30.0040.00417.66
8.1.20.0040.00417.68
8.1.10.0000.00717.52
8.1.00.0050.00317.41
8.0.300.0040.00418.77
8.0.290.0000.00716.75
8.0.280.0080.00018.51
8.0.270.0000.00717.18
8.0.260.0060.00017.27
8.0.250.0000.00616.98
8.0.240.0030.00316.93
8.0.230.0070.00016.87
8.0.220.0030.00316.80
8.0.210.0060.00016.75
8.0.200.0030.00316.88
8.0.190.0020.00516.91
8.0.180.0030.00716.87
8.0.170.0050.00316.79
8.0.160.0030.00316.89
8.0.150.0070.00016.87
8.0.140.0000.00816.64
8.0.130.0000.00513.27
8.0.120.0030.00716.71
8.0.110.0070.00016.80
8.0.100.0040.00416.70
8.0.90.0000.00816.89
8.0.80.0060.01616.84
8.0.70.0000.00716.86
8.0.60.0040.00416.89
8.0.50.0040.00416.69
8.0.30.0060.01217.26
8.0.20.0100.01117.40
8.0.10.0000.00817.01
8.0.00.0070.01016.62
7.4.330.0030.00315.08
7.4.320.0000.00716.36
7.4.300.0030.00316.61
7.4.290.0030.00516.53
7.4.280.0070.00016.40
7.4.270.0040.00416.44
7.4.260.0000.00716.52
7.4.250.0060.00316.37
7.4.240.0000.00816.54
7.4.230.0000.00716.59
7.4.220.0070.01016.56
7.4.210.0030.01216.47
7.4.200.0070.00016.60
7.4.160.0060.00916.46
7.4.150.0060.01217.40
7.4.140.0080.01117.86
7.4.130.0080.00816.46
7.4.120.0120.00716.54
7.4.110.0140.00316.51
7.4.100.0100.00716.60
7.4.90.0060.01216.39
7.4.80.0110.00819.39
7.4.70.0040.01516.50
7.4.60.0070.01016.18
7.4.50.0070.01016.65
7.4.40.0040.01416.51
7.4.30.0030.01416.48
7.4.00.0100.00715.09
7.3.330.0030.00313.34
7.3.320.0030.00313.09
7.3.310.0040.00416.36
7.3.300.0000.00716.32
7.3.290.0050.01016.30
7.3.280.0090.01016.28
7.3.270.0060.01217.40
7.3.260.0100.00916.36
7.3.250.0100.00816.52
7.3.240.0090.00716.61
7.3.230.0110.00716.50
7.3.210.0060.01116.36
7.3.200.0130.00516.40
7.3.190.0110.00616.65
7.3.180.0140.00716.26
7.3.170.0090.00916.50
7.3.160.0140.00316.39
7.3.120.0070.01314.73
7.3.110.0070.01114.99
7.3.100.0120.00414.89
7.3.90.0100.00715.07
7.3.80.0040.01114.80
7.3.70.0030.01014.55
7.3.60.0120.00314.84
7.3.50.0030.00614.79
7.3.40.0070.01014.70
7.3.30.0110.00414.98
7.3.20.0000.01516.71
7.3.10.0110.00716.67
7.3.00.0090.00616.66
7.2.330.0030.01316.66
7.2.320.0110.00916.51
7.2.310.0100.00716.80
7.2.300.0080.00816.53
7.2.290.0070.01316.56
7.2.250.0030.01514.75
7.2.240.0040.01814.81
7.2.230.0040.00815.17
7.2.220.0110.00415.11
7.2.210.0100.00715.03
7.2.200.0100.01015.07
7.2.190.0000.01314.80
7.2.180.0040.00814.96
7.2.170.0060.00915.01
7.2.60.0040.00816.91
7.2.00.0030.01019.40
7.1.330.0060.00915.80
7.1.320.0070.00715.67
7.1.310.0160.00315.65
7.1.300.0030.01015.80
7.1.290.0040.00815.71
7.1.280.0030.01315.43
7.1.270.0070.01015.58
7.1.260.0060.00915.88
7.1.200.0100.00315.78
7.1.100.0040.00717.98
7.1.70.0130.00316.75
7.1.60.0100.00719.75
7.1.50.0110.01416.85
7.1.00.0070.07322.54
7.0.200.0480.00614.71
7.0.90.1930.00019.93
7.0.80.1800.00020.05
7.0.70.2100.00020.06
7.0.60.2570.00019.94
7.0.50.2630.00020.27
7.0.40.1770.00020.34
7.0.30.1700.00020.37
7.0.20.1600.00020.21
7.0.10.1630.00020.36
7.0.00.1700.00020.39
5.6.240.0930.00020.61
5.6.230.0700.00020.63
5.6.220.0700.00020.62
5.6.210.1030.00020.57
5.6.200.0770.00021.07
5.6.190.0900.00021.08
5.6.180.0700.00021.10
5.6.170.0800.00021.08
5.6.160.0800.00021.10
5.6.150.1070.00021.11
5.6.140.0700.00021.08
5.6.130.0770.00021.21
5.6.120.0770.00021.21
5.6.110.0730.00021.13
5.6.100.0930.00021.06
5.6.90.0900.00021.00
5.6.80.0830.00020.54
5.6.70.0930.00020.52
5.6.60.0730.00020.47
5.6.50.0700.00020.46
5.6.40.0700.00020.54
5.6.30.0730.00020.42
5.6.20.0700.00020.47
5.6.10.0700.00020.46
5.6.00.0630.00020.42
5.5.380.0830.00020.53
5.5.370.0800.00020.39
5.5.360.0830.00020.52
5.5.350.0800.00020.52
5.5.340.0700.00020.95
5.5.330.0700.00020.95
5.5.320.0800.00020.87
5.5.310.0770.00020.69
5.5.300.0900.00020.77
5.5.290.0730.00020.89
5.5.280.0830.00020.87
5.5.270.0800.00020.93
5.5.260.0830.00020.84
5.5.250.0770.00020.51
5.5.240.0700.00020.23
5.5.230.0770.00020.10
5.5.220.0730.00020.28
5.5.210.0700.00020.17
5.5.200.0700.00020.08
5.5.190.0830.00020.24
5.5.180.0730.00020.29
5.5.160.0700.00020.30
5.5.150.0800.00020.13
5.5.140.0700.00020.29
5.5.130.0670.00020.29
5.5.120.0630.00020.24
5.5.110.0670.00020.06
5.5.100.0730.00020.09
5.5.90.0700.00020.14
5.5.80.0830.00020.23
5.5.70.0770.00020.13
5.5.60.0970.00020.14
5.5.50.0630.00020.19
5.5.40.0630.00020.17
5.5.30.0700.00020.14
5.5.20.0930.00019.96
5.5.10.0730.00020.14
5.5.00.0730.00020.04
5.4.450.0700.00019.41
5.4.440.0700.00019.54
5.4.430.0730.00019.50
5.4.420.0770.00019.51
5.4.410.0630.00019.47
5.4.400.0630.00019.20
5.4.390.0670.00019.09
5.4.380.0700.00019.06
5.4.370.0800.00019.19
5.4.360.0770.00019.08
5.4.350.0730.00019.04
5.4.340.0670.00019.28
5.4.320.0630.00019.09
5.4.310.0600.00019.18
5.4.300.0670.00019.07
5.4.290.0630.00019.21
5.4.280.0670.00018.93
5.4.270.0630.00018.90
5.4.260.0670.00019.15
5.4.250.0630.00019.07
5.4.240.0830.00019.20
5.4.230.0970.00019.02
5.4.220.0870.00019.08
5.4.210.0800.00019.29
5.4.200.0730.00019.09
5.4.190.0870.00019.13
5.4.180.0600.00019.02
5.4.170.0630.00019.07
5.4.160.0670.00019.13
5.4.150.0900.00019.07
5.4.140.0770.00016.68
5.4.130.0600.00016.69
5.4.120.0630.00016.55
5.4.110.0630.00016.66
5.4.100.0670.00016.65
5.4.90.0700.00016.38
5.4.80.0570.00016.62
5.4.70.0600.00016.59
5.4.60.0630.00016.56
5.4.50.0600.00016.39
5.4.40.0600.00016.63
5.4.30.0630.00016.25
5.4.20.0630.00016.54
5.4.10.0700.00016.31
5.4.00.0670.00015.86
5.3.290.0630.00014.72
5.3.280.0700.00014.75
5.3.270.0870.00014.64
5.3.260.0700.00014.63
5.3.250.0630.00014.61
5.3.240.0630.00014.62
5.3.230.0600.00014.61
5.3.220.0800.00014.53
5.3.210.0630.00014.63
5.3.200.0700.00014.55
5.3.190.0670.00014.58
5.3.180.0600.00014.69
5.3.170.0630.00014.44
5.3.160.0700.00014.61
5.3.150.0600.00014.57
5.3.140.0600.00014.57
5.3.130.0730.00014.58
5.3.120.0670.00014.55
5.3.110.0630.00014.56
5.3.100.0670.00014.08
5.3.90.0600.00014.04
5.3.80.0600.00014.14
5.3.70.0730.00013.94
5.3.60.0570.00013.88
5.3.50.0570.00013.83
5.3.40.0630.00013.95
5.3.30.0600.00013.79
5.3.20.0570.00013.65
5.3.10.0600.00013.66
5.3.00.0600.00013.68
5.2.170.0500.00011.19
5.2.160.0500.00011.16
5.2.150.0530.00011.15
5.2.140.0600.00011.15
5.2.130.0500.00011.03
5.2.120.0470.00011.13
5.2.110.0470.00011.26
5.2.100.0470.00011.06
5.2.90.0500.00011.09
5.2.80.0470.00011.10
5.2.70.0500.00011.09
5.2.60.0570.00011.07
5.2.50.0530.00011.04
5.2.40.0530.00010.94
5.2.30.0500.00010.93
5.2.20.0500.00011.00
5.2.10.0470.00010.88
5.2.00.0500.00010.66
5.1.60.0400.00010.11
5.1.50.0470.00010.09
5.1.40.0430.0009.99
5.1.30.0430.00010.32
5.1.20.0470.00010.48
5.1.10.0430.00010.13
5.1.00.0430.00010.15
5.0.50.0330.0008.61
5.0.40.0300.0008.33
5.0.30.0470.0008.29
5.0.20.0330.0008.26
5.0.10.0330.0008.27
5.0.00.0470.0008.21
4.4.90.0270.0005.86
4.4.80.0300.0005.89
4.4.70.0230.0005.82
4.4.60.0270.0005.86
4.4.50.0270.0005.89
4.4.40.0430.0005.89
4.4.30.0300.0005.82
4.4.20.0270.0005.89
4.4.10.0270.0005.90
4.4.00.0400.0005.89
4.3.110.0300.0005.77
4.3.100.0270.0005.81
4.3.90.0230.0005.78
4.3.80.0370.0005.77
4.3.70.0330.0005.77
4.3.60.0300.0005.77
4.3.50.0270.0005.76
4.3.40.0370.0005.71
4.3.30.0230.0005.15
4.3.20.0270.0005.16
4.3.10.0270.0005.20
4.3.00.0230.0005.20

preferences:
32.14 ms | 403 KiB | 5 Q