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I'm trying to create a simple program to take serial numbers as an input and then searche them to find out what year the product was made in.
I am having some trouble getting a std::string to hold both numbers and letters.
std::string serial;
serial = b1234;
For example, if I run this through my compiler, I get the error message 'invalid digit in decimal constant'.
Is there a simple way to hold letters and numbers together in a string?
Basic C++ syntax says that string literals are delimited by " quotation marks.
const std::string serial = "b1234";
No. A a std::string is a string of characters, so you can't save integers in that string.
You're trying to write "b1234", I guess. Have you read any tutorial on C++ strings?
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I'm working on a regular expression email validation assignment and it is working pretty well. I can match based on all the criteria I'm asked to. Here is my current pattern:
^([a-zA-Z0-9.\-\_\+]+)#([a-zA-Z0-9.\-\_\+]+)$
I also want to check that it begins with an alphabetic character. So I changed my pattern to this:
^[a-zA-Z]([a-zA-Z0-9.\-\_\+]+)#([a-zA-Z0-9.\-\_\+]+)$
And that works fine and only produces the match when the first character is alphabetic. BUT, the matches that are produced cut off the first character. So for example, if I try:
Billy#bobby.com
The match for the user-id before the # sign is coming back as "illy". I want it to come back as "Billy"
See the regex in action here: https://pythex.org/?regex=%5E%5Ba-zA-Z%5D(%5Ba-zA-Z0-9.%5C-%5C_%5C%2B%5D%2B)%40(%5Ba-zA-Z0-9.%5C-%5C_%5C%2B%5D%2B)%24&test_string=b2ill..%2B..DSD_y.23%40bobby.com&ignorecase=0&multiline=0&dotall=0&verbose=0
Nick gave me the help I needed. Here was my final pattern
^([a-zA-Z][a-zA-Z0-9.-_+]+)#([a-zA-Z0-9.-_+]+[a-zA-Z])$
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My code was converted to these random characters at some point after I saved my program using Vi. I did this project for a grade in one of my college courses and didn’t get any credit, despite the fact that I spent hours working on my code for this to happen. If anyone knows how to convert it back to C++ I would be thankful.
Turns out I had saved my file under the wrong folder and I was able to recover my original file. Thanks to all for helping out with this! It seems like it always tends to be something so simple...
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How do I match a string with " alphanumeric characters, underscore and any number of open and closed square braces ".
Example : " CDN_MBIT_hresp_s_reg[0]_MB_hresp_s_reg[1]bbjabs_chiansmokrs[6] "
I tried $line=~/[a-zA-Z0-9_/[/]]/;
This seems doesn't work.
P.S. This question is quite similar to Regex Matching Square Brackets
but not same
Thank you in advance.
Wrong slash used for escaping.
/[a-zA-Z0-9_\[\]]/
Alternatively, you could simply use
/[\w\[\]]/
Both of those match exactly one character. If you wanted to capture the string, you'd want
/([\w\[\]]+)/
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I have just started to learn C++ and i would like to get some help.
The user needs to type an ID number and the format has to be the following. The first character B and the other 4 any integer.
Im trying to check if the character format are right.
So far i have this:
if ((isalpha(id[0])=='B' ) && (isdigit(id.at(1))) && (isdigit(id.at(2))) ......
{
//do something
}
else
{
cout << "Wrong format" << endl;
}
but even if i type example B8745 it says wrong format.
You are comparing the result of isalpha, which is boolean, to character literal 'B'.
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A program I'm debugging is receiving SIGINT at this point:
#0 0x00007ffff590784e in toupper () from /lib/x86_64-linux-gnu/libc.so.6
The code in question is this:
std::string search = name;
std::transform(search.begin(), search.end(), search.begin(), ::toupper);
Right now I don't know whats the content, but special symbols are allowed.
I already got that I'm doing something wrong here, sinse its actually UTF-8 and I should be converting it to std::wstring before performing case transformations. Howover, even though I was doing it the wrong way I don't understand why it should crash.
What are the reasons for toupper to crash for SIGINT? And how can I avoid that some user input can this to my server application?
UTF-8 uses numbers that will appear negative when viewed as a signed char (which is the usual). Giving those negative numbers to toupper gives undefined behavior.
Try:
std::transform(search.begin(), search.end(), search.begin(),
[](unsigned char ch) {return ::toupper(ch); });
...and see if things don't work a little better.