How do you concatenate a char to a string

i am trying to concatenate an unsigned char to a string but its not working

Code:

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int main(){

string s= "ABCDE";
unsigned char a='vv;
s=s+a;


}

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Code:

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#include <string>
#include <iostream>


int main(int argc, char* argv[])
{
        std::string stringDemo = "Hello";
        char c = 'v';
        stringDemo += c;
        std::cout << stringDemo; // prints Hellov
        stringDemo.push_back(c);
        std::cout << stringDemo; // prints Hellovv
}

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Quote:

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Originally Posted by Serapth

Code:

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#include <string>
#include <iostream>


int main(int argc, char* argv[])
{
    std::string stringDemo = "Hello";
    char c = 'v';
    stringDemo += c;
    std::cout << stringDemo; // prints Hellov
    stringDemo.push_back(c);
    std::cout << stringDemo; // prints Hellovv
}

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it works fine if its a char but once i use an unsigned char ,it does not work

Why do you want to use an unsigned char?

Anyway, if you know that the value of the unsigned char will be in the range of char, the solution is to cast:

Code:

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stringDemo.push_back(static_cast<char>(c));

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Quote:

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Originally Posted by laserlight

Why do you want to use an unsigned char?

Anyway, if you know that the value of the unsigned char will be in the range of char, the solution is to cast:

Code:

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stringDemo.push_back(static_cast<char>(c));

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i am using it for characters that are in the range 0-255 thats why i am using unsigned char.I wont know the range because the characters are being fetched from a file

Ah, then instead of using a std::string, use a std::vector<unsigned char>.

Quote:

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Originally Posted by laserlight

Ah, then instead of using a std::string, use a std::vector<unsigned char>.

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Thanks

Or use wstring.

Code:

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#include <string>
#include <iostream>


int main(int argc, char* argv[])
{
    std::wstring stringDemo = L"Hello";
    unsigned char c = 'v';
    stringDemo += c;
    std::wcout << stringDemo; // prints Hellov
}

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Although frankly, wstring is always such a pain in the .... to work with.

Using wstring will allow you to do this though:

Code:

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    std::wstring stringDemo = L"Hello";
    unsigned char c = static_cast<unsigned char>(199);
    stringDemo += c;
    std::wcout << stringDemo; // prints Hello╟

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Quote:

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Originally Posted by Serapth

Or use wstring.

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I may be wrong, but in theory, the range of a wchar_t may well be the same as that of a signed char, since they have the same constraints on implementation defined limits. So, I reason if that if you want to store unsigned chars, then store unsigned chars.

Can't basic_string<unsigned char> be used ?

I'm not sure that basic_string is portable or standard-compliant. to my knowledge, string and wstring are specified by the standard, but no mention of how they must be implemented. I may be wrong about this.

Quote:

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Originally Posted by Elkvis

I'm not sure that basic_string is portable or standard-compliant. to my knowledge, string and wstring are specified by the standard, but no mention of how they must be implemented. I may be wrong about this.

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basic_string is part of the standard library, but then the stuff like string literals won't exist for basic_string<unsigned char> (except maybe now there's some user defined literals thing, but I'm not familiar with that at all).

basic_string is standard, but char_traits is not standard for unsigned char. Thus, you probably won't be able to use basic_string with unsigned char.
You can supply your own traits struct/class if you want, though.

This works, but I couldn't get it working with any sort of streams.
How would I use custom traits ?

Code:

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basic_string<unsigned char> s;
s+=static_cast<unsigned char>(200);

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Aren't user defined literals about adding custom suffixes to data ?

Quote:

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Originally Posted by manasij7479

Aren't user defined literals about adding custom suffixes to data ?

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C++11 - Wikipedia, the free encyclopedia

Quote:

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Originally Posted by manasij7479

This works, but I couldn't get it working with any sort of streams.

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You need to instantiate unsigned char streams like basic_ifstream<unsigned char>, which also require char_traits.