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The best thing to do is to use the algorithm
remove_if
and isspace:
remove_if(str.begin(), str.end(), isspace);
Now the algorithm itself can't change the container(only modify the values), so it actually shuffles the values around and returns a pointer to where the end now should be. So we have to call string::erase to actually modify the length of the container:
str.erase(remove_if(str.begin(), str.end(), isspace), str.end());
We should also note that remove_if will make at most one copy of the data. Here is a sample implementation:
template<typename T, typename P>
T remove_if(T beg, T end, P pred)
T dest = beg;
for (T itr = beg;itr != end; ++itr)
if (!pred(*itr))
*(dest++) = *itr;
return dest;
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Can you use Boost String Algo? http://www.boost.org/doc/libs/1_35_0/doc/html/string_algo/usage.html#id1290573
erase_all(str, " ");
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Hi, you can do something like that. This function deletes all spaces.
string delSpaces(string &str)
str.erase(std::remove(str.begin(), str.end(), ' '), str.end());
return str;
I made another function, that deletes all unnecessary spaces.
string delUnnecessary(string &str)
int size = str.length();
for(int j = 0; j<=size; j++)
for(int i = 0; i <=j; i++)
if(str[i] == ' ' && str[i+1] == ' ')
str.erase(str.begin() + i);
else if(str[0]== ' ')
str.erase(str.begin());
else if(str[i] == '\0' && str[i-1]== ' ')
str.erase(str.end() - 1);
return str;
If you want to do this with an easy macro, here's one:
#define REMOVE_SPACES(x) x.erase(std::remove(x.begin(), x.end(), ' '), x.end())
This assumes you have done #include <string> of course.
Call it like so:
std::string sName = " Example Name ";
REMOVE_SPACES(sName);
printf("%s",sName.c_str()); // requires #include <stdio.h>
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string replaceinString(std::string str, std::string tofind, std::string toreplace)
size_t position = 0;
for ( position = str.find(tofind); position != std::string::npos; position = str.find(tofind,position) )
str.replace(position ,1, toreplace);
return(str);
use it:
string replace = replaceinString(thisstring, " ", "%20");
string replace2 = replaceinString(thisstring, " ", "-");
string replace3 = replaceinString(thisstring, " ", "+");
Removes all whitespace characters such as tabs and line breaks (C++11):
string str = " \n AB cd \t efg\v\n";
str = regex_replace(str,regex("\\s"),"");
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I used the below work around for long - not sure about its complexity.
s.erase(std::unique(s.begin(),s.end(),[](char s,char f){return (f==' '||s==' ');}),s.end());
when you wanna remove character ' ' and some for example - use
s.erase(std::unique(s.begin(),s.end(),[](char s,char f){return ((f==' '||s==' ')||(f=='-'||s=='-'));}),s.end());
likewise just increase the || if number of characters you wanna remove is not 1
but as mentioned by others the erase remove idiom also seems fine.
Just for fun, as other answers are much better than this.
#include <boost/hana/functional/partial.hpp>
#include <iostream>
#include <range/v3/range/conversion.hpp>
#include <range/v3/view/filter.hpp>
int main() {
using ranges::to;
using ranges::views::filter;
using boost::hana::partial;
auto const& not_space = partial(std::not_equal_to<>{}, ' ');
auto const& to_string = to<std::string>;
std::string input = "2C F4 32 3C B9 DE";
std::string output = input | filter(not_space) | to_string;
assert(output == "2CF4323CB9DE");
string str = "2C F4 32 3C B9 DE";
str.erase(remove(str.begin(),str.end(),' '),str.end());
cout << str << endl;
output: 2CF4323CB9DE
I created a function, that removes the white spaces from the either ends of string. Such as
" Hello World ", will be converted into "Hello world".
This works similar to strip, lstrip and rstrip functions, which are frequently used in python.
string strip(string str) {
while (str[str.length() - 1] == ' ') {
str = str.substr(0, str.length() - 1);
while (str[0] == ' ') {
str = str.substr(1, str.length() - 1);
return str;
string lstrip(string str) {
while (str[0] == ' ') {
str = str.substr(1, str.length() - 1);
return str;
string rstrip(string str) {
while (str[str.length() - 1] == ' ') {
str = str.substr(0, str.length() - 1);
return str;
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I'm afraid it's the best solution that I can think of. But you can use reserve() to pre-allocate the minimum required memory in advance to speed up things a bit. You'll end up with a new string that will probably be shorter but that takes up the same amount of memory, but you'll avoid reallocations.
EDIT: Depending on your situation, this may incur less overhead than jumbling characters around.
You should try different approaches and see what is best for you: you might not have any performance issues at all.
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