This was give by Scoot Aaronsson in his lectures.
Print the following, the second time in quotes . (The program)
"Print the following, the second time in quotes" (The output)
I don't get this. What I understand is this :
Print the following, the second time in quotes.
", the second time in quotes"
This may be a silly question but can anyone just explain how am I wrong or right ?
Related
I'm honestly a novice on scilab.
I'm using print function to create .txt file with my character matrix in it.
But , when I open txt file, double quote appeared. I just want words without "".
This is how I'm using print
Compterendu(1,1)= "Medecin demandeur: "
fileresname= fullfile(RES_PATH, "compterendu.txt")
print(fileresname,Compterendu)
And, compterendu.txt was printed out like this.
Would be so grateful for any help!!
Thanks
Why do you use "print" ? After looking into the doc, yes, it is used to produce the same text as when you type the expression or the variable name on the command line. Hence it does print double quotes for strings. If you need something more basic use lower level i/o commands, like mputl.
S.
How can a text file be multiplied in by a constant using shell commands?
For e.g there is a text file consisting the following numbers
-255.9641842033
-255.9667588863
-256.9777650145
-258.9777662459
-259.9777661194
This needs to be multiplied with a constant 19.123456789123 and save in new text file. How can the above be accomplished?
Looking forward to a reply.
This might be close, using Perl:
perl -pe 's/([+-]?[0-9.]+)/$1*19.123456789123/ge' YourFile
Sample Output
-4894.92001617493
-4894.96925301402
-4914.3031850202
-4952.55012214707
-4971.67357651707
That kind of says... "capture anything that starts with an optional plus or minus and has a bunch digits and decimal points and call it capture group 1. Replace that with whatever it was multiplied by your magic number. The e at the end, says to evaluate the right side as an expression rather than take it as a literal. The g at the end says to do it each and every time it occurs on each line, rather than just the first time."
I need to write this solution as an AWK command. I am stuck on the last question:
Write a one line shell command that will count all lines in a file called "file.txt" that begin with a decimal number in parenthesis, containing a mix of both upper and lower case letters, and end with a period.
Example(s):
This is the format of lines we want to print. Lines that do not match this format should be skipped:
(10) This is a sample line from file.txt that your script should
count.
(117) And this is another line your script should count.
Lines like this, as well as other non-matching lines, should be skipped:
15 this line should not be printed
and this line should not be printed
Thanks in advance, I'm not really sure how to tackle this in one line.
This is not a homework solution service. But I think I can give a few pointers.
One idea would be to create a counter, and then print the result at the end:
awk '<COND> {c++} END {print c}'
I'm getting a bit confused by the terminology. First you claim that the lines should be counted, but in the examples, it says that those lines should be printed.
Now of course you could do something like this:
awk '<COND>' file.txt | wc -l
The first part will print out all lines that follow the condition, but the output will be parsed to wc -l which is a separate program that counts the number of lines.
Now as to what the condition <COND> should be, I leave to you. I strongly suggest that you google regular expressions and awk, it shouldn't be too hard.
I think the requirement is very clear
Write a one line shell command that will count all lines in a file called "file.txt" that begin with a decimal number in parenthesis, containing a mix of both upper and lower case letters, and end with a period.
1. begin with a decimal number in parenthesis
2. containing a mix of both upper and lower case letters
3. end with a period
check all three conditions. Note that in 2. it doesn't say "only" so you can have extra class of characters but it should have at least one uppercase and one lowercase character.
The example mixes concepts printing and counting, if part of the exercise it's very poorly worded or perhaps assumes that the counting will be done by wc by a piped output of a filtering script; regardless more attention should have been paid, especially for a student exercise.
Please comment if anything not clear and I'll add more details...
I would like to implement a small subset of siri/cortana like features in command line.
For e.g.
$ What is the sum of 100 and 1000
> Response: 1100
$ What is the product of 10 and 12
> Response: 120
The questions are predefined regular expressions. It needs to call the matching function in ruby.
Pattern: What is the sum of (\d)+ and (\d)+
Ruby method to call: sum(a,b)
Any pointers/suggestion is appreciated.
That sounds exactly like cucumber, maybe take a look and see if you can just use their classes to hack something together :) ?
You could do something like the following:
question = gets.chomp
/\A.*(sum |product |quotient |difference )\D+([0-9]+)\D+([0-9]+).*\z/.match question
send($1, $2.to_i, $3.to_i)
Quick explanation for anyone that may be new to matching in Ruby:
This gets a line of input from the command line and scans it for a function name (i.e. sum, product, etc) followed by a space and potentially some non-digit characters. Then, it looks for a first number (similarly followed by a space and 0 or more non-digit characters) and a second number followed by nothing or anything. The parentheses determine what gets assigned to the variables preceded by a $, i.e. the substring that matches the contents of the first set of parentheses gets assigned to $1.
Next, it calls the method whose name is the value of $1 with the arguments (casted to integers) found in $2 and $3.
Obviously, this isn't generalized at all--you're putting the method names in the regex, and it's taking a fixed number of arguments--but it'll hopefully be useful for getting you on the right track.
Hi I am writing a bash script and I have a string
foo=1.0.3
What I want to do is examine the '3'. The first thing I did was get rid of the periods by doing this. bar=echo $foo|tr '.' ' ' with backticks around echo until the last single quote (not sure how to accomplish writing that.
When I do an echo $bar it prints 1 0 3. Now how do I create a variable that holds only the 3? thank you very much
As you are no doubt learning about bash, there are many many ways to achieve your goals. I think #Mat's answer using bar=${foo##*.} is the best so far, although he doesn't explain how or why it works. I strongly recommend you check out the bash tutorial on tldp, it is my goto source when I have questions like this. For string manipulation, there is a section there that discusses many of the different ways to go about this sort of thing.
For example, if you know that foo is always going to be 5 characters long, you can simply take the fifth character from it:
bar=${foo:4}
That is, make bar the fifth position of foo (remember, we start counting from zero, not from one).
If you know it is always going to be the last position of foo, then you can just count backwards:
bar=${foo: -1}
Notice there is a space between the -1 and the colon, you need that (or parenthesis) to escape the negative sign.
To explain #Mat's answer, I had to look at the link I provided above. Apparently the double pound signs (hash mark, octothorpe, whatever you want to call them) in the expression:
${string##substring}
Mean to delete longest match of $substring from front of $string. So you are looking for the longest match of *. which equates to everything before a dot. Pretty cool, huh?
This should work:
bar=$(echo $foo|cut -d. -f3)
If you know you only want the part after the last dot (not the third item in a .-separated list) you can also do this:
bar=${foo##*.}
Advantage: no extra process or subshell started.
One way: Build an array and take position 2:
array=(`echo $foo | tr . ' '`)
echo ${array[2]}
This should also work too:
echo $foo | awk -F. '{print $3}'