如何用转义字符替换字符串中的所有特殊字符？

Question

If I had a string that looked like \\"A\\\\nB\\" , how do I transform it to look like "A\\nB" ?

The \\n portion should work as a new line. It should not be printing "A\\nB", it should be printing as follows:

A
B

Answer 1

This should do the work:

if(example.size() > 1) {
    for (auto i = 0ul; i < example.size() - 1; ++i) // loop through the string char by char
        if (example[i] != '\\' || (example[i + 1] == '\\'))
            result += example[i]; // if the current one is a \ and the next char is different to \ (for the case of \\) remove it
    if (example[example.size() - 1] == '\\' && example[example.size() - 1] == '\\') result += '\\'; // check for the last char
} else if(example.size() == 1 && example[0] != '\\') result+=example[0]; // check for special case there the string is just one char long

Answer 2

You can create a separate function for removing escape characters from your std::string in a following way:

std::string remove_escape_char(std::string const& s) {
    std::string result;
    auto it = s.begin();
    while (it != s.end()) {
        char c = *it++;
        if (c == '\\' && it != s.end()) {
            switch (*it++) {
            case '\\':
                c = '\\';
                break;
            case 'n':
                c = '\n';
                break;
            default: 
                continue;
            }
        }
        result += c;
    }

    return result;
}

and then the function for removing special characters from std::string :

void remove_special_char(std::string& str, char c) {
    auto position = str.find(c);
    while (position != std::string::npos) {
        str.erase(position, 1);
        position = str.find(c);
    }
}

You can use above two functions like:

std::string str{"\"A\\nB\""};
remove_special_char(str, 0x22); // remove "
std::cout << remove_escape_char(str) << std::endl;

Now the output should be:

A
B

Demo