求一正则表达式

Question

asdfa_25.png
asdfa_50.png
要一个正则表达式去匹配他们，前面是固定的只有  25  和  50  不同
aasdfasdfaD000000.zip    红色部分是数字这个正则表达式如何写

Answer 1

preg_match_all('/asdfa_(\d+)\.png/', $string, $matches);

Answer 2

aasdfasdfaD000000.zip    红色部分是数字这个正则表达式如何写   数字式六位怎么写

Answer 3

preg_match_all('/asdfa_(\d{6})\.png/', $string, $matches);

Answer 4

preg_match_all('/aasdfasdfaD(\d{6})\.png/', $string, $matches);

Answer 5

preg_match_all('/aasdfasdfaD_(\d{6})\.zip/', $string, $matches);