If I have a string courseID with a string that has the general form of "MATH202". The first few letters represent the subject of the class. If i want to extract those first 4 characters and set a new string subject to those 4 characters how would I do so?
Could I loop through the first string 4 times and set that letter to the second string with that letter?
Or is there a better way?
Use std::string::substr:
string subject = courseID.substr(0, 4);
Related
I want to check if a string only contains:
Letters
Numbers
Underscores
Periods
in Flutter, I tried the following to get only the letters but even if other characters are there it returns true if it contains a letter:
String mainString = "abc123";
print(mainString.contains(new RegExp(r'[a-z]')));
As I told it returns true since it contains letters, but I want to know if it only contains letters.
Is there a way to do that?
The problem with your RegExp is that you allow it to match substrings, and you match only a single character. You can force it to require that the entire string be matched with ^ and $, and you can match against one or more of the expression with +:
print(RegExp(r'^[a-z]+$').hasMatch(mainString));
To match all the characters you mentioned:
print(RegExp(r'^[A-Za-z0-9_.]+$').hasMatch(mainString));
the basic way of doing this is as follow:
define a list of acceptable characters:
// for example
List<String> validChar = ["1", "2", "3", "t"];
loop through all character of your string and check its validity:
// given text
String x = "t5";
bool valid = true;
for(int i=0; i<x.length; i++){
if(!validChar.contains(x[i])){
valid = false;
}
}
print(valid);
just change the x and validChar as your need.
I need to check strings like *11F23H3* that start and end with a *and have 7 uppercase literals or numbers in between. So far I have:
if (!barcode.match('[*A-Z0-9*]')) {
console.error(`ERROR: Barcode not valid`);
process.exitCode = 1;
}
But this does not cover strings like *11111111111*. How would the correct regex look like?
I need to check strings like 11F23H3 that start and end with a *and have 7 uppercase literals or numbers in between
You can use this regex:
/\*[A-Z0-9]{7}\*/
* is regex meta character that needs to be escaped outside character class
[A-Z0-9]{7} will match 7 characters containing uppercase letter or digits
RegEx Demo
Code:
var re = /\*[A-Z0-9]{7}\*/;
if (!re.test(barcode)) {
console.error(`ERROR: Barcode ${barcode} in row ${row} is not valid`);
process.exitCode = 1;
}
Note that if barcode is only going to have this string then you should also use anchors like this to avoid matching any other text on either side of *:
var re = /^\*[A-Z0-9]{7}\*$/;
If I want search first occurrence of letter in str1. If my str include both letter and number and symbol, but First I just want search location of letter like"a","b","c","d"...
can I create a string arr
string str[]={"a","b","c","d","e"....};
str1="signal a: a<= '0';";
str1.find(str,0);
can I do like this?
And I want to ask another question about string size
string str="signal a";
cout<<str.size()<<endl;
size of this string should be 8, but it actually just gives me 86?
I have a file that contains rows and columns of information like:
104857 Big Screen TV 567.95
573823 Blender 45.25
I need to parse this information into three separate items, a string containing the identification number on the left, a string containing the item name, and a double variable containing the price. The information is always found in the same columns, i.e. in the same order.
I am having trouble accomplishing this. Even when not reading from the file and just using a sample string, my attempt just outputs a jumbled mess:
string input = "104857 Big Screen TV 567.95";
string tempone = "";
string temptwo = input.substr(0,1);
tempone += temptwo;
for(int i=1 ; temptwo != " " && i < input.length() ; i++)
{
temptwo = input.substr(j,j);
tempone += temp2;
}
cout << tempone;
I've tried tweaking the above code for quite some time, but no luck, and I can't think of any other way to do it at the moment.
You can find the first space and the last space using std::find_first_of and std::find_last_of . You can use this to better split the string into 3 - first space comes after the first variable and the last space comes before the third variable, everything in between is the second variable.
How about following pseudocode:
string input = "104857 Big Screen TV 567.95";
string[] parsed_output = input.split(" "); // split input string with 'space' as delimiter
// parsed_output[0] = 104857
// parsed_output[1] = Big
// parsed_output[2] = Screen
// parsed_output[3] = TV
// parsed_output[4] = 567.95
int id = stringToInt(parsed_output[0]);
string product = concat(parsed_output[1], parsed_output[2], ... ,parsed_output[length-2]);
double price = stringToDouble(parsed_output[length-1]);
I hope, that's clear.
Well try breaking down the files components:
you know a number always comes first, and we also know a number has no white spaces.
The string following the number CAN have whitespaces, but won't contain any numbers(i would assume)
After this title, you're going to have more numbers(with no whitespaces)
from these components, you can deduce:
grabbing the first number is as simple as reading in using the filestream <<.
getting the string requires you to check until you reach a number, grabbing one character at a time and inserting that into a string. the last number is just like the first, using the filestream <<
This seems like homework so i'll let you put the rest together.
I would try a regular expression, something along these lines:
^([0-9]+)\s+(.+)\s+([0-9]+\.[0-9]+)$
I am not very good at regex syntax, but ([0-9]+) corresponds to a sequence of digits (this is the id), ([0-9]+\.[0-9]+) is the floating point number (price) and (.+) is the string that is separated from the two number by sequences of "space" characters: \s+.
The next step would be to check if you need this to work with prices like ".50" or "10".
I wanted to match the words in string with reverse order.
We wanted to put validation to prompt user, if name exists in reverse order.
For example:
If name column has the value, 'Viral,Tennis'
Now if user enters a new name with the value, 'Tennis,Viral'
Then how can we match reverse order of word using regex or some other way?
I am using C#.net for development.
You could take a look at the Regex.Split(String input, String regex) and do something like so:
String[] userEntry = Regex.Split(userString, "\\s+");
StringBuilder sb = new StringBuilder()
for (int i = userEntry.Length -1; i >= 0; i--)
{
sb.append(userEntry[i]).append(" ");
}
String result = sb.ToString();
//Do Validation
That would do the trick, however, you need to keep in mind that things will get a little bit messy if you do not want to change the order of special symbols such as the comma. You could easily remove those and do any validation without special symbols.
EDIT: It depends on what you mean by special symbols. The regex [^a-zA-z0-9]+ will match any character which is not a letter (upper or lower case) and which is also not a number. So you could easily do something like so:
string input = ...
string pattern = "[^a-zA-z0-9]+";
string replacement = "";
Regex rgx = new Regex(pattern);
string result = rgx.Replace(input, replacement);
The above should yield a string which is only made from letters and digits. White spaces will also be removed.