Differences in usage of php functions var_dump, var_export, and print_r

Warning: fopen(slsl.txt) [function.fopen]: failed to open stream: No such file or directory in E:mywwwyangtestbase1.php on line 6
array(6) { [ 0]=> int(1) [1]=> int(1) [2]=> int(32) [3]=> int(322) [4]=> int(3433) [ 5]=> array(3) { [0]=> int(32) [1]=> int(232) [2]=> int(23232) } }
int(1234)
string( 11) "alsdfl;asdf"
string(1) "a"
bool(false)
array ( 0 => 1, 1 => 1, 2 => 32, 3 => 322, 4 => 3433, 5 => array ( 0 => 32, 1 => 232, 2 => 23232, ), )
1234
'alsdfl;asdf'
'a '
false

Array ( [0] => 1 [1] => 1 [2] => 32 [3] => 322 [4] => 3433 [5] => Array ( [0] => 32 [1] => 232 [2] => 23232 ) )
1234
alsdfl;asdf
a

Pay attention to the above output, believe it Everyone can understand the difference between the functions var_dump, var_export, and print_r. Note that the last one is not posted, but it does not display anything. I hope to be helpful.