Quoting strings in C++ - c++

Question

In Pascal Lazarus/Delphi, we have a function QuotedStr() that wraps any string within single quotes.
Here's an example of my current C++ code:
//I need to quote tblCustomers
pqxx::result r = txn.exec( "Select * from \"tblCustomers\" ");
Another one:
//I need to quote cCustomerName
std::cout << "Name: " << r[a]["\"cCustomerName\""];
Similar to the above, I have to frequently double-quote strings. Typing this in is kind of slowing me down. Is there a standard function I can use for this?
BTW, I develop using Ubuntu/Windows with Code::Blocks. The technique used must be compatible across both platforms. If there's no function, this means that I must write one.

Answer 1

C++14 added std::quoted which does exactly that, and more actually: it takes care of escaping quotes and backslashes in output streams, and of unescaping them in input streams. It is efficient, in that it does not create a new string, it's really a IO manipulator. (So you don't get a string, as you'd like.)
#include <iostream>
#include <iomanip>
#include <sstream>
int main()
{
std::string in = "\\Hello \"Wörld\"\\\n";
std::stringstream ss;
ss << std::quoted(in);
std::string out;
ss >> std::quoted(out);
std::cout << '{' << in << "}\n"
<< '{' << ss.str() << "}\n"
<< '{' << out << "}\n";
}
gives
{\Hello "Wörld"\
}
{"\\Hello \"Wörld\"\\
"}
{\Hello "Wörld"\
}
As described in its proposal, it was really designed for round-tripping of strings.

Answer 2

Using C++11 you can create user defined literals like this:
#include <iostream>
#include <string>
#include <cstddef>
// Define user defined literal "_quoted" operator.
std::string operator"" _quoted(const char* text, std::size_t len) {
return "\"" + std::string(text, len) + "\"";
}
int main() {
std::cout << "tblCustomers"_quoted << std::endl;
std::cout << "cCustomerName"_quoted << std::endl;
}
Output:
"tblCustomers"
"cCustomerName"
You can even define the operator with a shorter name if you want, e.g.:
std::string operator"" _q(const char* text, std::size_t len) { /* ... */ }
// ...
std::cout << "tblCustomers"_q << std::endl;
More info on user-defined literals

Answer 3

String str = "tblCustomers";
str = "'" + str + "'";
See more options here

Answer 4

No standard function, unless you count std::basic_string::operator+(), but writing it is trivial.
I'm somewhat confused by what's slowing you down - quoted( "cCustomerName" ) is more characters, no? :>

Answer 5

You could use your own placeholder character to stand for the quote, some ASCII symbol that will never be used, and replace it with " just before you output the strings.

Answer 6

#include <iostream>
#include <string>
struct quoted
{
const char * _text;
quoted( const char * text ) : _text(text) {}
operator std::string () const
{
std::string quotedStr = "\"";
quotedStr += _text;
quotedStr += "\"";
return quotedStr;
}
};
std::ostream & operator<< ( std::ostream & ostr, const quoted & q )
{
ostr << "\"" << q._text << "\"";
return ostr;
}
int main ( int argc, char * argv[] )
{
std::string strq = quoted( "tblCustomers" );
std::cout << strq << std::endl;
std::cout << quoted( "cCustomerName" ) << std::endl;
return 0;
}
With this you get what you want.

Answer 7

What about using some C function and backslash to escape the quotes?
Like sprintf_s:
#define BUF_SIZE 100
void execute_prog() {
//Strings that will be predicted by quotes
string param1 = "C:\\users\\foo\\input file.txt", string param2 = "output.txt";
//Char array with any buffer size
char command[BUF_SIZE];
//Concating my prog call in the C string.
//sprintf_s requires a buffer size for security reasons
sprintf_s(command, BUF_SIZE, "program.exe \"%s\" \"%s\"", param1.c_str(),
param2.c_str());
system(command);
}
Resulting string is:
program.exe "C:\users\foo\input file.txt" "output.txt"
Here is the documentation.