c++ remove whitespace from string and keep the same size

To remove whitespace from a string in C++ while keeping the same size, you can use the std::remove_if function from the <algorithm> header along with a lambda function. Here are the steps to achieve this:

  1. Include the necessary headers: cpp #include <algorithm> #include <string>

  2. Define a lambda function that checks if a character is whitespace: cpp auto isWhitespace = [](char c) { return std::isspace(static_cast<unsigned char>(c)); };

  3. Create a string variable and assign the input string to it: cpp std::string inputString = "This is a string with whitespace.";

  4. Use the std::remove_if function to remove the whitespace from the string: cpp inputString.erase(std::remove_if(inputString.begin(), inputString.end(), isWhitespace), inputString.end());

Let's break down the std::remove_if function call:

  • inputString.begin() and inputString.end() specify the range of characters to process, which is the entire string.
  • isWhitespace is the unary predicate function that determines if a character is whitespace.
  • std::remove_if moves all the non-whitespace characters to the beginning of the string and returns an iterator pointing to the first element after the removed characters.
  • inputString.erase() erases the characters from the iterator returned by std::remove_if to the end of the string, effectively removing the whitespace.

After these steps, the inputString will contain the original string without any whitespace, and its size will remain the same.

Here's the complete code:

#include <algorithm>
#include <cctype>
#include <string>

int main() {
    auto isWhitespace = [](char c) { return std::isspace(static_cast<unsigned char>(c)); };

    std::string inputString = "This is a string with whitespace.";

    inputString.erase(std::remove_if(inputString.begin(), inputString.end(), isWhitespace), inputString.end());

    return 0;
}

Please note that the std::isspace function from the <cctype> header is used to check if a character is whitespace. This function handles not only the space character (' '), but also other whitespace characters such as tabs and newlines.