c++ : replacing a char in a string

cb951303 · 06-06-2005, 12:19 PM

Quote:

I understand that you might not be able to enter the values in the compiler, but since you are reading them from file in
the first place, you could set up a resource file where you could store these characters and read them in at the beginning of
the program.

I haven't tested this out because I don't have Turkish fonts, but it seems to me like it should work.

actually I already tried that, the thing is I also used the replace function like this:

Code:

replace(str_in.begin(), str_in.end(), 'ö', 'o')

but in this case if str_in's value is given in the source code, there is no problem but if I type it in the console (with cin), It doesn't work at all.

So what you're saying will surely work, but not with a input string :/

beforemath · 06-06-2005, 02:09 PM

A bit of a question:
It seems that when I perform explicit conversion

Code:

(int)random_char

I get the ascii value for that character.
When I try

Code:

(char)random_int

I get the character for that ascii value.

Even this seems to also be allowed (or at least, as far as I can tell):

Code:

replace(str_in.begin(), str_in.end(), (char)(-121), 'c');
replace(str_in.begin(), str_in.end(), (char)(-89), 'g');
replace(str_in.begin(), str_in.end(), (char)(-115), 'i');

Do simple conversions like that not work with expanded character sets at the command line, then?

carl.waldbieser · 06-06-2005, 05:48 PM

The problem is that for function templates, the template parameters are deduced by the compiler based on the types you are passing in as parameters. The replace function is really a template function. It looks like:

Code:

template <class ForwardIterator, class T>
void replace(ForwardIterator first, ForwardIterator last, const T& old_value, const T& new_value)

So if you pass in iterator, iterator, int, char, it looks for the prototype

Code:

void replace(iterator, iterator, int, char)

Since the last two parameters are always the same type, the compiler can't find it, and it barks at you.

If you are going to be using characters outside the ASCII and extended ASCII set (i.e. characters that require more than 8 bits), you should probably consider using wstring instead of string. However, the global streams cin, cout, and cerr used for console input, output, and error are only capable of handling char data-- not wchar_t data.

Here is my previous example, tweaked to use a wstring instead of a string. This uses the *NIX device /dev/tty to write to the console, since I can't send a wide-character string to a cout (a character stream).

Code:

#include <string>
#include <iostream>
#include <fstream>
#include <algorithm>

int main()
{
   using std::wstring;
   using std::wofstream;
   using std::endl;
   using std::replace;

   wstring s(L"Hejjo Worjd!");

   replace(s.begin(), s.end(), L'j', L'l');

   // Create a wide-character output stream to write to the console.
   wofstream wcout("/dev/tty");

   wcout << s << L'\n';

   return 0;
}