Sams Teach Yourself C++ in 21 Days

69: // Converts a character array to a String

70: String::String(const char * const cString)

71: {

72: itsLen = strlen(cString);

73: itsString = new char[itsLen+1];

74: for (int i = 0; i < itsLen; i++)

75: itsString[i] = cString[i];

76: itsString[itsLen]=’\0’;

77: ASSERT(Invariants());

78: }

79:

80: // copy constructor

81: String::String (const String & rhs)

82: {

83: itsLen=rhs.GetLen();

84: itsString = new char[itsLen+1];

85: for (int i = 0; i < itsLen;i++)

86: itsString[i] = rhs[i];

87: itsString[itsLen] = ‘\0’;

88: ASSERT(Invariants());

89: }

90:

91: // destructor, frees allocated memory

92: String::~String ()

93: {

94: ASSERT(Invariants());

95: delete [] itsString;

96: itsLen = 0;

97: }

98:

99: // operator equals, frees existing memory

100: // then copies string and size

101: String& String::operator=(const String & rhs)

102: {

103: ASSERT(Invariants());

104: if (this == &rhs)

105: return *this;

106: delete [] itsString;

107: itsLen=rhs.GetLen();

108: itsString = new char[itsLen+1];

109: for (int i = 0; i < itsLen;i++)

110: itsString[i] = rhs[i];

111: itsString[itsLen] = ‘\0’;

112: ASSERT(Invariants());

113: return *this;

114: }

115:

116: //non constant offset operator

766 Day 21

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