How to erase all spaces in a string?

If you want to trim spaces at both ends with std::string class object, you can use std::string::find_first_not_of[^] and std::string::string/find_last_not_of[^.

A bit of logic and std::string::substr[^], you are able to create a function that will do the same as .NET System::String::Trim[^] function does for managed strings.

The code should look like this (not tested):

using namespace std;

string trim(const string &source, const string &trim_chars)
{
  size_t pos1 = source.find_first_not_of(trim_chars);
  size_t pos2 = source.find_last_not_of(trim_chars);

  // Optional: optimize case where the string is already trimmed.
  if (pos1 == string::npos && pos2 == string::npos) { return source; }

  if (pos1 == string::npos) { pos1 = 0; }
  if (pos2 == string::npos) { pos2 = source.length(); }

  size_t trimmed_length = pos2 - pos1;
  return source.substr(pos1, trimmed_length);
}

string trim(const string &source)
{
  string trim_chars(" \t\r\n");  // Whatever you want to uses by default.
  return trim(source, trim_chars);
}

If you want to remove all spaces, then you might uses similar functions in a loop and construct a new string on the fly. Essentially, you would find first char that is not a space and next space after that and copy that part and then repeat until the remainding part of the string does not contains spaces anymore.

http://stackoverflow.com/questions/83439/remove-spaces-from-stdstring-in-c[^]