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I have a string like below:
std::string myString = "This is string\r\nIKO\r\n. I don't exp\r\nO091\r\nect some characters.";
Now I want to get rid of the characters between \r\n including \r\n.
So the string must look like below:
std::string myString = "This is string. I don't expect some characters.";
I am not sure, how many \r\n's going to appear.
And I have no idea what characters are coming between \r\n.
How could I use regex in this string?
Personally, I'd do a simple loop with find. I don't see how using regular expressions helps much with this task. Something along these lines:
string final;
size_t cur = 0;
for (;;) {
size_t pos = myString.find("\r\n", cur);
final.append(myString, cur, pos - cur);
if (pos == string::npos) {
break;
}
pos = myString.find("\r\n", pos + 2);
if (pos == string::npos) {
// Odd number of delimiters; handle as needed.
break;
}
cur = pos + 2;
}
Regular expressions are "greedy" by default in most regex libaries.
Just make your regex say "\r\n.*\r\n" and you should be fine.
EDIT
Then split your input using the given regex. That should yield two strings you can combine into the desired result.
Related
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I've asked to write code that gets a char array(sentence), if the there is an 'i' in the sentence I need to add the letter 'b' the letter 'i' again like this example:
pig -> pibig
I tried to use string.h functions but I didn't succeed to make it right.
Use std::string in string header file, and std::string::insert whenever you need to insert a char in string:
std::string my_string = "my satringa";
for (size_t i = 0; i < my_string.length(); ++i)
{
if (my_string.at(i) == 'a')
{
my_string.insert(i + 1, "b");
}
}
std::clog << my_string << std::endl;
Output:
> my sabtringab
If you are forced to use C-style strings, don't worry do all of your operations on std::string and then take the underlying stored string with std::string::c_str() as a C-style string (and don't forget to take a copy).
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I am working on a small project of mine, and I need to match a string to a regex value, and the first character of the match needs to start exactly at a certain index.
I need to do this in C++, but can't find a method or function that seems like it would work on cplusplus.com.
Eg. if I put in the string Stack overflow into the pattern f.ow
and an index of 3, it should return false. But if I set the index to 10, it should return true and allow me to find out what actually matched (flow). And if I put in an index of 11, it should also return false.
Try this function, hope this will work for you
#include<iostream>
#include<regex>
#include<string.h>
using namespace std;
bool exactRegexMatch(string str,int index){
regex reg("f(.)ow");
return regex_match(str.substr(index), reg);
}
int main(){
if(exactRegexMatch("Stack Overflow",10)){
cout<<"True"<<endl;
}
else{
cout<<"False"<<endl;
}
}
How to match a string to regex based on a certain index?
Pass the substring starting from the index as the string argument, and add ^ to the beginning of the regex so that it only matches when the pattern starts from the beginning of the substring.
This uses the whole string by constructing the regex.
strRx = `"^[\\S\\s]{" + strOffset + "}(f.ow)";
// make a regex out of strRx
or, use iterators to jump to the location to start matching from
bool FindInString( std::string& sOut, std::string& sInSrc, int offset )
{
static std::regex Rx("(f.ow)");
sOut = "";
bool bRet = false;
std::smatch _M;
std::string::const_iterator _Mstart = sInSrc.begin() + offset;
std::string::const_iterator _Mend = sInSrc.end();
if ( regex_search( _Mstart, _Mend, _M, Rx ) )
{
// Check that it matched at exactly the _Mstart position
if ( _M[1].first == _Mstart )
{
sOut = std::string(_M[1].first, _M[1].second);
bRet = true;
}
}
return bRet;
}
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I am new to c++ programming. I need some help,
I have string :
---- Input : "Name : $$ Enter Your Name2 $$"
I want to extract string between $$ symbols including symbols :
---- Output : "$$ Enter Your Name2 $$"
Please help me.
Regular Expression are very useful in this case.
C++11 has regex library.
#include <string>
#include <regex>
std::string parse_string(const std::string& str) {
static const std::string REGEX_STR = R"__(\$\$(\w|\W)*\$\$)__";
std::regex regex(REGEX_STR);
std::smatch regex_iterator;
if (std::regex_search(str, regex_iterator, regex)) {
return regex_iterator.str();
}
return std::string("");
}
The code can be improved but it should represent a good starting point. Specific case should be handled, for example: more $$*$$ in a string, etc...
Note:
R"__(\$\$(\w|\W)*\$\$)__"; is a raw string in order to make more readable the regex.
Just search the string for the delimiter:
std::string parse_string(const std::string& str, const std::string& delim) {
auto start = str.find(delim);
if (start == std::string::npos)
return "";
auto end = str.find(delim, start + delim.size());
if (end == std::string::npos)
return str.substr(start);
else
return str.substr(start, end - start + delim.size);
}
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getline(cin,s);
istringstream iss(s);
do
{
string sub;
iss>>sub;
q.insert(sub);
}while(iss);
I used this technique when question wanted me to split on the basis of space so can anyone explain me how to split when there's a particular delimiter like ';' or ':'.
Someone told me about strtok function but i am not able to get it's usage so it would be nice if someone could help.
First, don't use strtok. Ever.
There's not really a function for this in the standard library.
I use something like:
std::vector<std::string>
split( std::string const& original, char separator )
{
std::vector<std::string> results;
std::string::const_iterator start = original.begin();
std::string::const_iterator end = original.end();
std::string::const_iterator next = std::find( start, end, separator );
while ( next != end ) {
results.push_back( std::string( start, next ) );
start = next + 1;
next = std::find( start, end, separator );
}
results.push_back( std::string( start, next ) );
return results;
}
I believe Boost has a number of such functions. (I implemented
most of mine long before there was Boost.)
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How can I parse a string given by a user and swap all occurrences of the old substring with the new string. I have a function to work with but I am really uncertain when it comes to strings.
void spliceSwap( char* inputStr, const char* oldStr, const char* newStr )
The simplest solution is to use google (First link) here. Also be aware that in C++ we prefer std::string over const char *. Do not write your own std::string, use the built-in one. Your code seems to be more C than C++!
// Zammbi's variable names will help answer your question
// params find and replace cannot be NULL
void FindAndReplace( std::string& source, const char* find, const char* replace )
{
// ASSERT(find != NULL);
// ASSERT(replace != NULL);
size_t findLen = strlen(find);
size_t replaceLen = strlen(replace);
size_t pos = 0;
// search for the next occurrence of find within source
while ((pos = source.find(find, pos)) != std::string::npos)
{
// replace the found string with the replacement
source.replace( pos, findLen, replace );
// the next line keeps you from searching your replace string,
// so your could replace "hello" with "hello world"
// and not have it blow chunks.
pos += replaceLen;
}
}