SOS! how to do conditional search & replacement of strings in perl?

[walala]

Suppose I want to do conditional search & replacement:

I have the following input text file:

-------------------------------------------------------------------
_INST1832 B_1 59 135.301588688164E-18 M=1.0

_INST1833 S_4 47 52 VDD! PCH L=239.99999143598E-9 W=3.99999998990097E-6
+AD=2.04320002757108E-12 AS=1.58200004745507E-12 PD=5.36000015927129E-6
+PS=829.999976303952E-9 NRD=+2.50000001E-01 NRS=+2.50000001E-01 M=1.0
-------------------------------------------------------------------

I want to change the "_INST" in the lines where there is no "PCH" or "NCH"
patterns to "C", and change the "_INST" in the lines where there is "PCH" or
"NCH" to "M".

The result should be:

-------------------------------------------------------------------
C1832 B_1 59 135.301588688164E-18 M=1.0

M1833 S_4 47 52 VDD! PCH L=239.99999143598E-9 W=3.99999998990097E-6
+AD=2.04320002757108E-12 AS=1.58200004745507E-12 PD=5.36000015927129E-6
+PS=829.999976303952E-9 NRD=+2.50000001E-01 NRS=+2.50000001E-01 M=1.0
-------------------------------------------------------------------

What do I do? Can you give me the right "regular expression" which can do
such thing?

Thank you very much!

-Walala

 

[Gunnar Hjalmarsson]

I want to change the "_INST" in the lines where there is no "PCH"
or "NCH" patterns to "C", and change the "_INST" in the lines where
there is "PCH" or "NCH" to "M".

What do I do?

You study Perl documentation:

perldoc perlre
perldoc perlop

Also available on the web: http://www.perldoc.com/

Then you write the code yourself.

Can you give me the right "regular expression" which can do such
thing?

Yes, there are quite a few people who can do that.

 

[John W. Krahn]

Suppose I want to do conditional search & replacement:

I have the following input text file:
-------------------------------------------------------------------
_INST1832 B_1 59 135.301588688164E-18 M=1.0

_INST1833 S_4 47 52 VDD! PCH L=239.99999143598E-9 W=3.99999998990097E-6
+AD=2.04320002757108E-12 AS=1.58200004745507E-12 PD=5.36000015927129E-6
+PS=829.999976303952E-9 NRD=+2.50000001E-01 NRS=+2.50000001E-01 M=1.0
-------------------------------------------------------------------

I want to change the "_INST" in the lines where there is no "PCH" or "NCH"
patterns to "C", and change the "_INST" in the lines where there is "PCH" or
"NCH" to "M".

The result should be:
-------------------------------------------------------------------
C1832 B_1 59 135.301588688164E-18 M=1.0

M1833 S_4 47 52 VDD! PCH L=239.99999143598E-9 W=3.99999998990097E-6
+AD=2.04320002757108E-12 AS=1.58200004745507E-12 PD=5.36000015927129E-6
+PS=829.999976303952E-9 NRD=+2.50000001E-01 NRS=+2.50000001E-01 M=1.0

perl -pe'/PCH|NCH/ ? s/^_INST/M/ : s/^_INST/C/' yourfile



John

 

[Mina Naguib]

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perl -pe'/PCH|NCH/ ? s/^_INST/M/ : s/^_INST/C/' yourfile

Or with a hint of evil obfuscation

perl -pe 's#^_INST# /[PN]CH/ ? "M" : "C" #e' yourfile


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