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I'm new to programming, so I was wondering...
If I have an input file consisting of 100 lines, how do I read only up to line 50 and print out each line?
Thanks.
create a fstream object fstream f("filename");
Keep a counter, read lines from file till the counter less than 50
Something like this
counter = 0;
while((counter < 50) && (f.good())
{
getline(f,str);
cout<<str<<endl;
counter++
}
Note: this is not the full code, but guideline how to do.
Please use 'fstream' to read your file and count each 'readline'. Each 'readline' means a full line which terminated with '\n'(return value without it). That should be useful.
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In a text with many lines in notepad++, some lines are unintentionally broken into the next line without an end point. I want to merge lines that are more than 10 characters long that do not end with a dot(.) with of regex. Also put a space between merged lines.
For example, the following text:
tttttttttt
aaaaaaaaaaaaaaaa
bbbbbbbbbbbbbbbbbb.
ccccccccccccccccc
dddddddddddddddddd.
Convert to:
tttttttttt
aaaaaaaaaaaaaaaa bbbbbbbbbbbbbbbbbb.
ccccccccccccccccc dddddddddddddddddd.
I also tried the following regex code but it didn't work:
[^\.]\n
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I am struggling through this date extraction. I have a date like this
("D("yyyy-mm-dd")).
I want to get this "yyyy-mm-dd" and I cannot strip ("D(") this also because I have this format in other places so I tried like this
first searching the string but I am not sure if I am on right track
eg. intabc = istrdate.SearchSubString("D(");
so please suggest how can I get this value.
Input is
"(D(YYYY-MM-DD))"
OUTPUT that I want
(YYYY-MM-DD)
What i have done(not correct way I think )
intabc = istrdate.SearchSubString("D(");
you can use substr() and string::erase() functions in c++98
string str = "\"D(\"yyyy-mm-dd\")";
string result = str.substr(3);
result.erase(result.end() - 1)
result.erase(result.end() - 1)
if you are using c++11 you can also use string::pop_back() method.
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how to write a cpp program for replace string using only 1 text file
for example if in text file abc.txt
Hello
how are you
good
bye
i want output like
Hello
how are you
bad
bye
all above thing will be done in text file
Pretty easy. Open the file, get the text. Then iterate throw each word and ask the user if he/she wants to change that word. If yes, write new word on new file. If not, write old word on new file.
Now you just need to translate that to c++
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I am designing a GUI in Matlab,
I have a folder called sth. It contains many files having same structure like,
filename_1_something.mat
filename_2_something.mat
In order to loop over filenames by selecting via index, I need to find a resulting string like this;
filename_%d_something.mat
So I don't need to read all the files in the dir. Two of the filenames are enough to compare strings and find the different char array item and change by %d.
Or anything different than this also appreciated.
using the regex provided by #rock321987 -
names = dir('*.mat');
num = length(names);
expression = '\w*_\d+_\w*\.mat';
for n = 1:num
str = names(n).name;
nameList{n} = regexp(str,expression,'match')
end
works on:
test_1_something.mat
test_10_something.mat
changing the regex to just \w*_\w*\.mat
works for
test_1.mat
1_test.mat
test_1_something.mat
test_10_something.mat
but also works for anything with an string joined by underscore .mat
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If you open a *.gif file with notepad the file starts with GIF89
but for the *.jpeg files the first characters aren't something like GIF89
How can I detect that my file is *.jpeg with it's file first characters?
According to The JPEG File Interchange Format:
(After a 2 byte "SOI" marker...)
the next 2 bytes will be 0xFFE0
the next 2 bytes are unimportant for this detection
the next 5 bytes will be "JFIF" (including the null-terminator)