How to remove spaces before and after in the specified path?

[rajesh5479]

Hello!

How to remove spaces before and after in the specified path?

I have a string value getting like this - "C: \ Test file \ Temp1"

My question is remove spaces before and after (colon & Backslash): \ only (not in text)

Expecting output :"C:\Test file\Temp1"

I have written code like below

path = L"C: \ Test file \ Temp1";
int length = path.length();

for (int i = 0; i < length; i++)
{
   if (path [i] == ': ' || '\ ')
   {
	path .erase(i, 1);
	length--;
        i--;
   }
}

how can i solve this issue ? can help someone.

[coder777]

This may give you an idea:

#include <string>

int main()
{
  std::string path = "C: \\ Test file \\ Temp1";

  std::string::size_type pos;
  while((pos = path.find(" \\")) != std::string::npos)
  {
    path.erase(pos, 1);
  }
}

Note that for "\ " it is similar. You just need + 1 on pos.

[seeplus]

From the example given, need to replace " \ " with just "\". So consider:

#include <string>
#include <iostream>

int main()
{

	std::string path = "C: \\ Test file \\ Temp1";

	for (std::string::size_type pos = 0; (pos = path.find(" \\ "), pos) != std::string::npos; path.replace(pos, 3, "\\"));

	std::cout << path << std::endl;
}

which displays:

C:\Test file\Temp1

as required.

Note that if there is more than one space, or sometimes before only or after only - then a different approach is needed.

[coder777]

So my example removes all leading spaces. Here is how to remove all trailing spaces as well:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

#include <iostream> #include <string> int main() { std::string path = "C: \\ Test file \\ Temp1"; std::string::size_type pos; while((pos = path.find(" \\")) != std::string::npos) { path.erase(pos, 1); } while((pos = path.find("\\ ")) != std::string::npos) { path.erase(pos + 1, 1); } std::cout << path << std::endl; return 0; }

Output: C:\Test file\Temp1

There are two loops because there might be backslashes without leading and/or trailing spaces. So this works in all cases.

[rajesh5479]

Thanks you so much @coder777

it's working all the cases leading and trailing spaces.

is there any way to both the cases in single while loop leading and trailing cases?

[coder777]

is there any way to both the cases in single while loop leading and trailing cases?

Yes, but that requires more attention.

You need a start_pos. Set it to 0.

Search for the backslash only using start_pos (as seeplus showed).

Set bool found_space = false;

Within the loop check whether theres is a trailing (pos + 1) space. If so remove it, set found_space = true. Note that before checking the space you need to check whether the backslash isn't the last character.

Similar for the leading backspace:

Within the loop check whether theres is a leading (pos - 1) space. If so remove it, set found_space = true. Note that before checking the space you need to check whether the backslash isn't the first character.

When found_space == false set start_pos = pos + 1;

This is a good execise for you to check your understanding of the subject...

[rajesh5479]

Hi coder777

I tried with in same loop to remove leading and trailing spaces of given path but i'm not getting expected output please help me.

#include <iostream>
#include <string>

int main()
{
  std::string path = "C:               \\         Test file            \\            Temp1";
  stringx::size_type pos = 0;
  bool found_space = false;
  while ((pos = path.find("\\")) != stringx::npos)
  {
	if (pos == path.find(" \\"))
	{
	     path.erase(pos, 1);
	     found_space = true;
	}
        else if (pos == path.find("\\ "))
	{
             path.erase(pos+1, 1);
	     found_space = true;
	}
   }
}

[coder777]

Okay, you did not get what told you. I have a simplier solution not so far from your try:

#include <iostream>
#include <string>

int main()
{
  std::string path = "C:               \\         Test file            \\            Te\\ mp1";

  std::string::size_type pos0 = std::string::npos;
  std::string::size_type pos1 = std::string::npos;
  do
  {
    pos0 = path.find(" \\");
    if(pos0 != std::string::npos)
      path.erase(pos0, 1);
    pos1 = path.find("\\ ");
    if(pos1 != std::string::npos)
      path.erase(pos1 + 1, 1);
  }
  while((pos0 != std::string::npos) || (pos1 != std::string::npos));

  std::cout << path << std::endl;

  return 0;
}

[seeplus]

Slightly different approach where the string is only iterated once and erases all the non-required consecutive spaces together, which for large strings will give a small performance benefit. Consider:

#include <string>
#include <iostream>

int main()
{
	std::string path = "\\  C: \\     Test   file    \\  Temp1\\ ";

	for (size_t pos = 0; (pos = path.find('\\', pos)) != std::string::npos; ++pos) {
		if (pos > 0)
			if (const size_t fl = path.find_last_not_of(' ', pos - 1); fl == std::string::npos) {
				path.erase(0, pos);
				pos = 1;
			} else {
				path.erase(fl + 1, pos - fl - 1);
				pos = fl + 2;
			}

		if (auto ff = path.find_first_not_of(' ', pos); ff == std::string::npos)
			path.erase(pos, ff);
		else
			path.erase(pos, ff - pos);
	}

	std::cout << "'" << path << "'" << std::endl;
}