无法将参数1从'char'转换为'const std :: basic_string <_Elem，_Traits，_Ax>＆'

Question

I am getting abpve error at line str.append(ch); in below code.

I basically want to append str with each char 'ch'.

If someone know the issue please correct my error.

int extract(unsigned char data, char i); // Signature of extract function


void decoded(istream& input,ostream& output)
    {   
        int cnt;
        int x;

        input.read((char*)&x,sizeof(x));


        cout<<x;
        cnt=x;
        string str;
        char ch;
        for ( ; ; ) 
        {
            char c;

            input.read((char*)&c,sizeof(char));

            if ( input )
            {
                //read_bit(c,output);
                for (int i=7; i>=0; i--)
                {     
                    if(cnt)
                        {
                        cnt--;
                        ch=(char)(((int)'0')+extract(c, i));

                        str.append(ch);// I am getting error at this line.

                        if(huffmanFindTable[str])
                        {
                            output.write((char*)&(huffmanFindTable[str]),sizeof(char));
                            str.clear();
                        }
                        else
                        {
                        }

                    }
                }
            }
            else
            break;
        }



    }

Answer 1

string::append has no member function taking a char as argument. You can append null-terminated char arrays or other stringS .

Answer 2

You can only append a "sequence" of character to a string. "append" is an operation on two (sequence) vector (take the word vector in a more generic sense) like objects.

You can do the following:

1. str.append(1, ch);
2. str+=ch;

Answer 3

Like the compiler says, there is no member function with the signature

str.append(ch);

You can use either

str.append(1, ch);

or the simpler

str.push_back(ch);