C++ TString::asChar方法代码示例

// compares object with parameter value and returns true if match, otherwise false
bool TString::equals( const TString &sText ) const {
    // initializes boolean to false
    bool check = 0;
    // compares char data targeted by mpText and parameter value
    if ( strcmp( mpText, sText.asChar() ) ) {
        return check; // if condition is true, returns false
    }
    return ++check; // returns true otherwise
}

// checks for assignment to self and returns if true
void TString::assign( const TString &sText ) {
    // tests for self-assignment
    if ( this != &sText ) {
        delete [] mpText; // frees heap memory allocated for char[] targeted by mpText
        mLength = sText.length(); // sets non null-byte length of array to be targeted by mpText to that of sText
        mpText = new char[ mLength + 1 ]; // initializes encapsulated char data with extra element for null byte
        strncpy( mpText, sText.asChar(), mLength ); // copies sText target to new memory targeted by mpText
        mpText[ mLength ] = 0; // sets last element in array targeted by mpText to null byte
    }
}

// deep copy ctor
TString::TString( const TString &sText ) {
    mLength = sText.length(); // sets non null-byte length of array to be targeted by mpText to that of sText
    mpText = new char[ mLength + 1 ]; // initializes encapsulated char data with extra element for null byte
    strncpy( mpText, sText.asChar(), mLength ); // copies sText target to new memory targeted by mpText
    mpText[ mLength ] = 0; // sets last element in array targeted by mpText to null byte
}

// note - you may need to change the definition of the main function to
// be consistent with what your C++ compiler expects.
int main()
{
    ofstream outfile (pOutfileName, ios::out);
    if( !outfile.is_open() )
    {
        cout << "Error - unable to open output file: " << pOutfileName << endl;
        return 1;
    }

    //cout << "Writing output to " << pOutfileName << "... please wait" << endl;
    //ostream& outstream = outfile;  // uncomment to write to file
    ostream& outstream = cout;  // uncomment to write directly to cout

    const char *mp = 0;
    int step = 0;
    outstream << "----- simple String class test ----- (09/16/2010)" << endl << endl;

    // const checks  (compile tests)
	// If there are compile errors in this section, then there are probably const specifiers missing from your
	// class definition, e.g.  the length() member function should be defined as a const member function so
	// it can be invoked on a const TString object, as should all other member functions that don't change the
	// state of 'this'.
    {
        if (0 != 0)  // only a compilation check for these methods at this point (for const). Tested further below.
        {
            const TString s0(pHello); // create a const TString object
            int n = s0.length();
            bool f = s0.equalsIgnoreCase(pHello);
            f = s0.equals(pHello);
            const char *p = s0.asChar();
            n = s0.indexOf('h');
            const TString s1(s0);  // const String object parameter

            TString s2;
            s2.assign(s0);  // const String object parameter
            s2.append(s0);  // const String object parameter
        }
    }

    // Default ctor
    outstream << "\n----- Step " << ++step << " - default ctor -----" << endl;
    {
        TString s0;  // default arg value
        outstream << "s0 using default ctor with default arg = \"" << s0.asChar() << "\" (length = " << s0.length() << ")" << endl;
        mp = (0 == s0.length()) ? "OK: " : "ERROR: ";
        outstream << mp << "length = " << s0.length() << endl;
        mp = (0 != s0.asChar()) ? "OK: " : "ERROR: ";
        outstream << mp << "asChar() return value " << hex << "0x" << reinterpret_cast<const int *>(s0.asChar()) << dec << endl;
        mp = ('\0' == *(s0.asChar())) ? "OK: null byte " : "ERROR: null byte not ";
        outstream << mp << "at position 0" << endl;
    }
    {
        TString s0(copyToTemp(pHello));  // char * parameter
        clearTemp();
        outstream << endl << "s0 using default ctor with char* parameter = \"" << s0.asChar() << "\" (length = " << s0.length() << ")" << endl;
        mp = (s0.length() == strlen(pHello)) ? "OK: " : "ERROR: ";
        outstream << mp << "length = " << s0.length() << endl;
        mp = (0 == strcmp(s0.asChar(), pHello)) ? "OK: " : "ERROR: ";
        outstream << mp << "value is \"" << s0.asChar() << "\"" << endl;
        mp = (s0.asChar() != pHello) ? "OK: different " : "ERROR: same ";
        outstream << mp << "pointer value returned from asChar()" << endl;
        mp = (s0.asChar() == s0.asChar()) ? "OK: same " : "ERROR: different ";
        outstream << mp << "pointer value returned for successive calls of asChar()" << endl;
    }


    // Copy ctor
    outstream << "\n----- Step " << ++step << " - copy ctor -----" << endl;
    {
        TString s0(copyToTemp(pHiMom));
        clearTemp();
        TString s1(s0);  // copy ctor
        outstream << "s1 using copy ctor = \"" << s1.asChar() << "\" (length = " << s1.length() << ")" << endl;
        mp = (s1.length() == s0.length() && s1.length() == strlen(pHiMom)) ? "OK: " : "ERROR: ";
        outstream << mp << "length = " << s1.length() << endl;
        mp = (s1.asChar() != s0.asChar()) ? "OK: different " : "ERROR: same ";
        outstream << mp << "pointer value returned from asChar()" << endl;
        mp = (0 == strcmp(s1.asChar(), pHiMom)) ? "OK: " : "ERROR: ";
        outstream << mp << "value is \"" << s1.asChar() << "\"" << endl;
    }
    {
        // Check copy of empty string
        TString s0;
        TString s1(s0);
        outstream << "s1 using copy ctor = \"" << s1.asChar() << "\" (length = " << s1.length() << ")" << endl;
        mp = (0 == s1.length()) ? "OK: " : "ERROR: ";
        outstream << mp << "length = " << s1.length() << endl;
        mp = (0 != s1.asChar()) ? "OK: " : "ERROR: ";
        outstream << mp << "asChar() return value " << hex << "0x" << reinterpret_cast<const int *>(s1.asChar()) << dec << endl;
        mp = (s1.asChar() != s0.asChar()) ? "OK: different " : "ERROR: same ";
        outstream << mp << "pointer value returned from asChar()" << endl;
        mp = ('\0' == *(s0.asChar())) ? "OK: null byte " : "ERROR: null byte not ";
        outstream << mp << "at position 0" << endl;
    }


    // append
    outstream << "\n----- Step " << ++step << " - append -----" << endl;
//.........这里部分代码省略.........