How do I print "\n" explicitly in a string in c++ - c++

Question

hi i have a unknown string in c++ containing "\n" "\t" etc.
say;
string unknown1=read_from_file();
if unknown1="\n\t\n\t\n\n\n\n\n" now I want to print
"\n\t\n\t\n\n\n\n\n"
to the screen explcitly other than a bunch of empty spaces.... how should I do that? remember that I don't know what is in unknown1...
to emphasize, I know that we could print \n explicitly if we change "\n" into "\n" for every such character... But the problem is that I don't know what is inside unknown1... It is read from a file....
Thanks for answering, however we have further concerns:
The procedure answered has one more porblem... Suppose I don't know that the only possible special character in the file is \n or \t... maybe there are something like \u ? \l ? i think we can't exhaust every possibility right? Is there kind of built in C++ function just to output the corresponding characters?

Answer 1

\n , \t are escape sequences, but you can print them by adding an extra \ before them, \\ is used to obtain a single backslash. A single backslash means it is an escape sequence ( if it is a valid one ), but two backslashes represent the backslash character, so whenever you need to output a backslash, just add two of them.
So, if you use
string unknown1="\\n\\t\\n\\t\\n\\n\\n\\n\\n";
You will get your desired output.
If you are reading from a file , then do something like this
string unknown1="\n\t\n\t\n\n\n\n\n";
for ( int i = 0 ; i < unknown1.length() ; i++ )
{
if( unknown1[i] == '\n')
cout<<"\\n";
}
Like that, you will have to check for each escape sequence that may be used.

Answer 2

Run specific checks for the non-printable characters you are worried about like this.
char c;
while(c!=EOF){
if(c=='\n')printf("\\n");
if(c=='\t')printf("\\t");
and so on and so forth.
c = the next charater;
}
oops, I wrote C instead of C++ but #Arun A.S has the right syntax

Answer 3

See below example. You can add your own characters to the switch to extend the characters it handles.
#include <iostream>
#include <string>
std::string escapeSpecialChars(const std::string& str)
{
std::string result;
for(auto c : str)
{
switch(c)
{
case '\n':
result += "\\n";
break;
case '\t':
result += "\\t";
break;
default:
result += c;
break;
}
}
return result;
}
int main()
{
std::string str = "\n\n\n\t";
std::cout << escapeSpecialChars(str);
return 0;
}

Answer 4

You could create your own function to print characters using a std::map:
void printChar( const char ch )
{
static const std::map< char, std::string > char_map = {
{ '\n', "\\n" }
// add mappings as needed
};
auto found = char_map.find( ch );
if ( found != char_map.end() )
std::cout << found->second;
else
std::cout << ch;
}
// usage
std::string str = "a\nbc";
for ( auto ch : str ) printChar ( ch );