php读取文件内容至字符串中，同时去除换行、空行、行首行尾空格（Zjmainstay原创）_php技巧

//输出:
aaaa,bbbb,cccc,dddd,eeee,ffff,gggg,hhhh,iiii,jjjj,kk kk,ll ll

//file.php内容：
aaaa

cccc
dddd
eeee
ffff
gggg
hhhh
iiii
jjjj
kk kk
ll ll


//file.php替换空格(x)、Tab(T)效果
aaaa

TTTT
cccc
ddddT
xxxxxxxxxxxT
eeeexxxxxxxxxx
ffff
gggg
hhhhxxxxxxxx
xxxxxxxxiiii
xxxxxxxxjjjjxxxxxxx
kkxxxkkTT
xxxxllxxllTT
Txxxxxxxxxx
TTTxx