这是整个程序，请帮助我，我已经尝试了一切，以找出内存的确切内容。问题是一切运行完美，但有一些额外的字符打印输出。
这是.h文件：
class MyString
{
public:
MyString();
MyString(const char *message);
MyString(const MyString &source);
~MyString();
const void Print() const;
const int Length() const;
MyString& operator()(const int index, const char b);
char& operator()(const int i);
MyString& operator=(const MyString& rhs);
bool operator==(const MyString& other) const;
bool operator!=(const MyString& other) const;
const MyString operator+(const MyString& rhs) const;
MyString& operator+=(const MyString& rhs);
friend ostream& operator<<(ostream& output, const MyString& rhs);
const int Find(const MyString& other);
MyString Substring(int start, int length);
private:
char *String;
int Size;
};
istream& operator>>(istream& input, MyString& rhs);
.cpp文件：
MyString::MyString()
{
char temp[] = "Hello World";
int counter(0);
while(temp[counter] != '\0')
{
counter++;
}
Size = counter;
String = new char [Size];
for(int i=0; i < Size; i++)
String[i] = temp[i];
}
//alternate constructor that allows for setting of the inital value of the string
MyString::MyString(const char *message)
{
int counter(0);
while(message[counter] != '\0')
{
counter++;
}
Size = counter;
String = new char [Size];
for(int i=0; i < Size; i++)
String[i] = message[i];
}
//copy constructor
MyString::MyString(const MyString &source)
{
int counter(0);
while(source.String[counter] != '\0')
{
counter++;
}
Size = counter+1;
String = new char[Size];
for(int i = 0; i <= Size; i++)
String[i] = source.String[i];
}
//Deconstructor
MyString::~MyString()
{
delete [] String;
}
//Length() method that reports the length of the string
const int MyString::Length() const
{
int counter(0);
while(String[counter] != '\0')
{
counter ++;
}
return (counter);
}
/*Parenthesis operator should be overloaded to replace the Set and Get functions of your previous assignment. Note that both instances should issue exit(1) upon violation of the string array bounaries.
*/
MyString& MyString::operator()(const int index, const char b)
{
if(String[index] == '\0')
{
exit(1);
}
else
{
String[index] = b;
}
}
char& MyString::operator()(const int i)
{
if(String[i] == '\0')
{
exit(1);
}
else
{
return String[i];
}
}
/*Assignment operator (=) which will copy the source string into the destination string. Note that size of the destination needs to be adjusted to be the same as the source.
*/
MyString& MyString::operator=(const MyString& rhs)
{
if(this != &rhs)
{
delete [] String;
String = new char[rhs.Size];
Size = rhs.Size;
for(int i = 0; i < rhs.Size+1 ; i++)
{
String[i] = rhs.String[i];
}
}
return *this;
}
/*Logical comparison operator (==) that returns true iff the two strings are identical in size and contents.
*/
bool MyString::operator==(const MyString& other)const
{
if(other.Size == this->Size) {
for(int i = 0; i < this->Size+1; i++)
{
if(&other == this)
return true;
}
}
else
return false;
}
//Negated logical comparison operator (!=) that returns boolean negation of 2
bool MyString::operator!=(const MyString& other) const
{
return !(*this == other);
}
//Addition operator (+) that concatenates two strings
const MyString MyString::operator+(const MyString& rhs) const
{
char* tmp = new char[Size + rhs.Size +1];
for(int i = 0; i < Size; i++)
{
tmp[i] = String[i];
}
for(int i = 0; i < rhs.Size+1; i++) {
tmp[i+Size] = rhs.String[i];
}
MyString result;
delete [] result.String;
result.String = tmp;
result.Size = Size+rhs.Size;
return result;
}
/*Addition/Assigment operator (+=) used in the following fashion: String1 += String2 to operate as String1 = String1 + String2
*/
MyString& MyString::operator+=(const MyString& rhs)
{
char* tmp = new char[Size + rhs.Size + 1];
for(int i = 0; i < Size; i++) {
tmp[i] = String[i];
}
for(int i = 0; i < rhs.Size+1; i++)
{
tmp[i+Size] = rhs.String[i];
}
delete [] String;
String = tmp;
Size += rhs.Size;
return *this;
}
istream& operator>>(istream& input, MyString& rhs)
{
char* t;
int size(256);
t = new char[size];
input.getline(t,size);
rhs = MyString(t);
delete [] t;
return input;
}
ostream& operator<<(ostream& output, const MyString& rhs)
{
if(rhs.String != '\0')
{
output << rhs.String;
}
else
{
output<<"No String to output\n";
}
return output;
}
/*MyString::Find that finds a string in a larger string and returns the starting location of the substring. Note that your string location starts from 0 and ends at length -1. If the string is not found, a value of -1 will be returned
*/
const int MyString::Find(const MyString& other)
{
int nfound = -1;
if(other.Size > Size)
{
return nfound;
}
int i = 0, j = 0;
for(i = 0; i < Size; i++) {
for(j = 0; j < other.Size; j++) {
if( ((i+j) >= Size) || (String[i+j] != other.String[j]) )
{
break;
}
}
if(j == other.Size)
{
return i;
}
}
return nfound;
}
/*MyString::Substring(start, length). This method returns a substring of the original string that contains the same characters as the original string starting at location start and is as long as length.
*/
MyString MyString::Substring(int start, int length)
{
char* leo = new char[length+1];
for(int i = start; i < start + length+1; ++i)
{
leo[i-start] = String[i];
}
MyString sub;
delete [] sub.String; sub.String = leo; sub.Size = Size;
return sub;
}
//Print() method that prints the string
const void MyString::Print() const
{
for(int i=0; i < Size; i++)
{
cout<<String[i];
}
cout<<endl;
}
main.cpp文件：
int main (int argc, char **argv)
{
MyString String1;
const MyString ConstString("Target string"); //Test of alternate constructor
MyString SearchString; //Test of default constructor that should set "Hello World".
MyString TargetString (String1); //Test of copy constructor
cout << "Please enter two strings. ";
cout << "Each string needs to be shorter than 256 characters or terminated by /\n." << endl;
cout << "The first string will be searched to see whether it contains exactly the second string. " << endl;
cin >> SearchString >> TargetString; // Test of cascaded string-extraction operator
if(SearchString.Find(TargetString) == -1) {
cout << TargetString << " is not in " << SearchString << endl;
}
else {
cout << TargetString << " is in " << SearchString << endl;
cout << "Details of the hit: " << endl;
cout << "Starting position of the hit: " << SearchString.Find(TargetString) << endl;
cout << "The matching substring is: " << SearchString.Substring(SearchString.Find(TargetString), TargetString.Length()-1)<<"\n";
}
return 0;
}
运行程序，你得到了这个：
请输入两个字符串。每个字符串需要短于256个字符或由/终止 。 将搜索第一个字符串以查看它是否包含完全第二个字符串。
首先
实
realt World首先不是
请帮助!!
答案 0 :(得分：0)
尝试在MyString::MyString(const char *message)构造函数
答案 1 :(得分：0)
@Sam的回答是正确的。我将添加它以帮助您了解正在发生的事情。
C和C ++字符串实际上是字符数组，遵循约束字符串以\0结尾的约定，有时称为NUL（ not null），这是一个所有位都是0
您的代码获得了第一部分，因为它创建了一个字符数组。但是，您不应用约定，该字符串必须以NUL终止。
然后，将不遵循NUL终止约定的字符串传递给cout， 遵循该约定。换句话说，它贯穿字符串，将每个字符打印到stdout，直到发生跨越内存中的字符\0。实际上相当幸运，它终止了。如果输出的字符数组中没有\0，它将继续运行，直到到达不属于您的程序的内存地址并且因分段错误而失败。