C ++十六进制计算器乘法 [英] C++ Hexadecimal Calculator Multiplication
问题描述
我遇到的问题是我的乘法方法仅处理一行，而目前没有前进到下一行.加法功能正常工作，并且我能够更新当前的十六进制数，但是由于某种原因，我只能让一行乘法工作.
I'm having issues where my multiplication method is only handling one row, it's currently not advancing to the next row. The add function is working properly, and I'm able to update the current hex number, but for some reason I can only get one line of multiplication to work.
Example input:
111# * 333# = 333
123# * 123# = 369
这是有问题的代码:
LList* Calculator::multiply(LList& left, LList& right) {
int product, carry = 0, lval = 0, rval = 0, zeros = 0;
bool calculating = true;
listnode *leftNode;
vector <LList*> addList;
listnode *rightNode;
LList* newHex;
while(calculating) {
leftNode = left.next();
if(leftNode == NULL) {
break;
}
else {
lval = leftNode->data;
}
//leftNode = left.next();
right.reset();
if(leftNode == NULL) {
calculating = false;
if(carry != 0) {
//newHex->insertTail(carry);
}
lval = 0;
break;
}
LList* curList = new LList;
addList.push_back(curList);
while(rightNode != NULL) {
// Add however zeros we need for
// each entry based on the zero counter
for(int i = 0; i < zeros; i++) {
curList->insertTail(0);
}
rightNode = right.next();
if(rightNode == NULL) {
}
else {
rval = rightNode->data;
product = lval * rval + carry;
carry = 0;
if(product >= 16) {
carry = (product / 16);
product = (product % 16);
}
curList->insertTail(product);
}
}
zeros++;
}
Calculator calc;
LList* temp;
// Add up everything in the addList
for(int i = 0; i < addList.size() - 1; i++) {
if(temp == NULL)
temp = calc.add(*addList[i], *addList[i+1]);
else
temp = calc.add(*addList[i+1], *temp);
}
newHex = temp;
// Delete it
for(int i = 0; i < addList.size(); i++) {
}
return newHex;
};
这是下一个方法:
listnode* LList::next() {
listnode* temp = view;
if(temp != NULL)
view = view->next;
if(view == NULL) {
}
return temp;
};
完整计划:
#include <iostream>
#include <vector>
#include <stdlib.h>
#include <string>
using namespace std;
#undef NULL
const int NULL = 0;
const char SENTINEL = '#';
typedef int element;
class listnode {
public:
element data;
listnode * next;
};
class LList {
private:
listnode * head;
listnode * tail;
listnode * view;
public:
LList();
~LList();
void read();
listnode* next();
void reset();
void print();
void insertTail(element val);
void clean();
element deleteHead();
};
class Calculator {
public:
Calculator();
inline LList* add(LList& left, LList& right);
inline LList* multiply(LList& left, LList& right);
};
Calculator::Calculator() {
};
LList* Calculator::add(LList& left, LList& right) {
int sum, carry = 0, lval = 0, rval = 0;
bool calculating = true;
listnode *leftNode;
listnode *rightNode;
LList* newHex = new LList;
while(calculating) {
leftNode = left.next();
rightNode = right.next();
if(leftNode == NULL) {
lval = 0;
}
else
lval = leftNode->data;
if(rightNode == NULL) {
rval = 0;
}
else
rval = rightNode->data;
if(leftNode == NULL && rightNode == NULL) {
calculating = false;
if(carry != 0) {
newHex->insertTail(carry);
}
break;
}
sum = lval + rval + carry;
carry = 0;
if(sum >= 16) {
carry = 1;
sum -= 16;
}
newHex->insertTail(sum);
}
return newHex;
};
LList* Calculator::multiply(LList& left, LList& right) {
int product, carry = 0, lval = 0, rval = 0, zeros = 0;
bool calculating = true;
listnode *leftNode;
vector <LList*> addList;
listnode *rightNode;
LList* newHex;
while(calculating) {
leftNode = left.next();
if(leftNode == NULL) {
break;
}
else {
lval = leftNode->data;
}
//leftNode = left.next();
right.reset();
if(leftNode == NULL) {
calculating = false;
if(carry != 0) {
//newHex->insertTail(carry);
}
lval = 0;
break;
}
LList* curList = new LList;
addList.push_back(curList);
while(rightNode != NULL) {
// Add however zeros we need for
// each entry based on the zero counter
for(int i = 0; i < zeros; i++) {
curList->insertTail(0);
}
rightNode = right.next();
if(rightNode == NULL) {
}
else {
rval = rightNode->data;
product = lval * rval + carry;
carry = 0;
if(product >= 16) {
carry = (product / 16);
product = (product % 16);
}
curList->insertTail(product);
}
}
zeros++;
}
Calculator calc;
LList* temp;
// Add up everything in the addList
for(int i = 0; i < addList.size() - 1; i++) {
if(temp == NULL)
temp = calc.add(*addList[i], *addList[i+1]);
else
temp = calc.add(*addList[i+1], *temp);
}
newHex = temp;
// Delete it
for(int i = 0; i < addList.size(); i++) {
}
return newHex;
};
listnode* LList::next() {
listnode* temp = view;
if(temp != NULL)
view = view->next;
if(view == NULL) {
}
return temp;
};
void LList::reset() {
view = head;
}
LList::LList(){
/*
next:
This is used to set the linked
list to NULL.
*/
head = NULL;
view = NULL;
};
void LList::print() {
listnode * temp;
int i = 0;
string printValues;
temp = head;
while(temp != NULL) {
int var = temp -> data;
char character = ' ';
if(i % 3 == 0 && i != 0)
printValues += ',';
i++;
if(var > 9 && var < 16) {
character = static_cast <char>(var + 65 - 10);
};
if (var <= 9 && var >= 0) {
character = static_cast <char>(var + 48);
};
if (var > 96 && var < 103) {
character = static_cast <char>(var + 97 + 10);
};
printValues += character;
temp = temp -> next;
}
string tempValues;
for(int i = printValues.length() - 1; i >= 0; i--)
tempValues += printValues[i];
cout << tempValues;
cout << endl;
};
void LList::read() {
string userval;
int i;
bool parsing = true;
char curval;
vector <int> values;
clean();
while(parsing) {
cin >> userval;
for(unsigned int i = 0; i < userval.length(); i++) {
curval = userval[i];
if(curval >= 48 && curval <= 57)
values.push_back(static_cast <int>(curval -
48));
if(curval >= 65 && curval <= 70)
values.push_back(static_cast <int>(curval -
65 + 10));
if(curval >= 97 && curval <= 102)
values.push_back(static_cast <int>(curval -
97 + 10));
if(curval == ' ')
break;
if(curval == SENTINEL) {
parsing = false;
break;
}
}
}
for(int i = values.size() -1; i >= 0; i--) {
insertTail(values[i]);
}
};
void LList::insertTail(element val) {
listnode * temp;
temp = new listnode;
temp -> data = val;
temp -> next = NULL;
if(head == NULL) {
head = temp;
view = head;
}
else
tail -> next = temp;
tail = temp;
};
void LList::clean() {
while(head != NULL)
deleteHead();
};
void validCommands() {
cout << "Valid commands are:" << endl;
cout << " e enter enter the current ";
cout << "hexadecimal ";
cout << "number from the keyboard" << endl;
cout << " a add add a new hexadecimal ";
cout << "number to the current hex. number" << endl;
cout << " m multiply ";
cout << "multiply a new hexadecimal number ";
cout << "by the current hex. number" << endl;
cout << " h help show this help menu" << endl;
cout << " q quit quit the program" << endl << endl;
};
element LList::deleteHead() {
listnode * temp;
temp = head;
head = head -> next;
delete temp;
return temp -> data;
};
LList::~LList(){
delete head;
};
int main() {
LList L, add,multiply;
Calculator calc;
L.insertTail(0);
char option;
bool run;
cout << "Hexadecimal Calculator, Ver 1.0.0 \n";
do {
/*
This do while is used to continuosly run the
program until the user decides to end.
*/
cout << "Current Hexadecimal number is: ";
L.print();
cout << endl;
cout << "Command (h for help): ";
cin >> option;
cout << endl << endl;
switch(option) {
case 'e' :
cout << "Enter a hexadecimal number ";
cout << "followed by #: ";
L.read();
cout << endl << "Entering completed.";
cout << endl << endl;
break;
case 'a' :
cout << "Adding a new hexadecimal number ";
cout << "to the current hex. number" << endl;
cout << endl;
cout << "Enter a hexadecimal ";
cout << "number, follow by #: ";
add.read();
cout << endl << "Addition completed.";
cout << endl;
L = *calc.add(L, add);
cout << endl;
break;
case 'm' :
cout << "Multiplying a new hexadecimal ";
cout << "number ";
cout << "to the current hex. number" << endl;
cout << endl;
cout << "Enter a hexadecimal ";
cout << "number, follow by #: ";
multiply.read();
cout << endl << "Multiplication completed.";
cout << endl;
L = *calc.multiply(L, multiply);
cout << endl;
break;
case 'h' : validCommands();
break;
case 'q' : run = false;
break;
};
} while (run);
exit(0);
}
推荐答案
while(rightNode != NULL)的第一个评估使用rightNode的未初始化值，当您运行程序时，该值恰好为非NULL.在此检查之后，在取消引用之前，rightNode被设置为来自right.next()的有效节点指针值.但是对于下一个左数字，rightnode在上一个循环中仍为NULL，因为它在right.reset()之后不会更新，因此对于第一个数字之后的每个数字，while(rightNode != NULL)总是从rightNode设置为NULL开始，因此所有循环在之后第一个被跳过.
The first evaluation of while(rightNode != NULL) uses an uninitialized value for rightNode, which happens to be non-NULL when you run the program. After this check, before it is dereferenced, rightNode is set to a valid node pointer value from right.next(). But for the next left digit, rightnode is still NULL from the previous loop, because it is not updated after right.reset(), so for every digit after the first, while(rightNode != NULL) always starts off with rightNode set to NULL, so all loops after the first one are skipped.
一旦修复此错误，就会暴露出另一个错误:在右数字循环内的curList中添加零，因此，每当处理右数字时就添加零.相反，应该在左数字循环内创建curList之后，在右数字循环前添加零.
Once this is fixed, another bug will be exposed: zeros are added to curList inside the right-digit loop, so the zeros get added whenever a right-digit is processed. Instead the zeros should be added before the right-digit loop, after curList is created within the left-digit loop.
还有另一个错误(我认为)-右数位循环结束后，任何进位值都未添加到curList的最后一位数-而是将其保存为下一个右数位的开头环形.这可能是有意为之，但我不认为它总是会停留在正确的数字位置(但在这一点上我可能是错的-我并没有过多地考虑各种可能性).
There is another bug (I think) -- after the right-digit loop ends, any carry value is not added to the last digit of curList -- instead it gets saved for the beginning of the next right-digit loop. This might be intentional, but I don't think it will always end up in the correct digit position (but maybe I'm wrong on this point -- I haven't dedicated much thought to the possibilities).
为了调试您的问题，我不得不复制您的代码，填写缺少的部分并修复错误.另外，还有一些样式问题，这些问题不是实际的错误或错误，但已知会引起问题.因此，这是我对测试版本进行的更改:
For debugging your problem, I had to duplicate your code, fill in missing parts and fix the bugs. Also, there were some style issues which are not actual mistakes or bugs, but are known to promote problems. So here are changes I made to my version for testing:
-
LList包含一个通过
next()和reset()访问的有状态迭代器(view).将来，您的代码的多个部分可能希望同时在同一个LList上进行迭代，但是它们将无法共享LList对象所拥有的单个迭代状态.迭代器对象解决了这个问题.
LList contains a stateful iterator (
view) accessed withnext()andreset(). In the future, multiple sections of your code might want to iterate over the same LList, at the same time, but they will not be able to share the single iteration state held by the LList object. Iterator objects solve this problem.
在用户"代码中使用原始指针:如果可能，应避免使用指针操纵，或者将其限制为库"代码-就像在LList对象中一样.不需要在Calculator类中处理指针.
Use of raw pointers in "user" code: Pointer manipulation should be avoided, if possible, or restricted to "library" code -- like within the LList object. There is no need to handle pointers inside the Calculator class.
变量应在其使用所需的最内部范围内声明.如果遵循此样式点，则代码的第一个问题就不会发生，其中rightNode从上一个循环中继承了一个值.
Variables should be declared inside the innermost scope required for their use. The code's first problem, where rightNode was carrying a value over from a previous loop, could not have happened if this style point was being followed.
在函数末尾不需要保留项的向量(addList)进行总结.我的版本将LList命名为prodSum.
There was no need to keep a vector (addList) of terms to sum up at the end of the function. My version keeps a running sum as the LList named prodSum.
这是我的代码版本，包括我自己的LList和Calculator :: add，因为您没有使它们可用.请注意，LList在这里与迭代器一起使用，而不是view成员.我的迭代器在其结束位置时可以被取消引用"，并赋予零.这样做是为了方便起见，因为对于任何值，都隐含一个在最高位上方的无数个高阶零字符串:
Here is my version of the code, including my own LList and Calculator::add, because you did not make those available. Note that LList works with iterators here, not a view member. My iterators can be "dereferenced" when at their end position, giving a zero. This was done for convenience, because an infinite string of high-order zeros above the highest digit is implied for any value:
#include <iostream>
#include <string>
#include <vector>
struct listnode {
int data;
listnode *next;
listnode(int data=0) : data(data), next(0) {}
};
class LList {
listnode *head, *tail; // head is least significant end
void delNodes() {
listnode* node = head;
while(node) {
listnode* todel = node;
node = node->next;
delete todel;
}
head = tail = 0;
}
public:
LList() : head(0), tail(0) {}
LList(std::string digits) : head(0), tail(0) {
for(auto it = digits.rbegin(); it != digits.rend(); ++it) {
if(*it >= '0' && *it <= '9') insertTail(*it - '0');
else if(*it >= 'a' && *it <= 'f') insertTail(*it - 'a' + 10);
else if(*it >= 'A' && *it <= 'F') insertTail(*it - 'A' + 10);
} }
LList(const LList& src) : head(0), tail(0) {
for(int data : src) { insertTail(data); }
}
~LList() { delNodes(); }
LList& operator = (const LList& src) {
delNodes();
for(int data : src) { insertTail(data); }
return *this;
}
void insertTail(int value) {
listnode *newnode = new listnode(value);
if(!head) {
head = tail = newnode;
} else {
tail->next = newnode;
tail = newnode;
} }
class iterator {
friend LList;
const listnode* node;
iterator(const listnode* node) : node(node) {}
public:
iterator& operator ++ () { if(node) node = node->next; return *this; }
int operator * () const { return node ? node->data : 0; }
bool operator != (iterator iter) const { return iter.node != node; }
bool operator == (iterator iter) const { return iter.node == node; }
};
iterator begin() const { return iterator(head); }
iterator end() const { return iterator(0); }
std::string get_digits() const {
static const char da[] = "0123456789abcdef";
std::string digits;
for(int d : *this) {
digits = da[d] + digits;
}
return digits;
}
};
LList add(const LList& left, const LList& right) {
LList sum;
auto liter = left.begin();
auto riter = right.begin();
int carry = 0;
while(liter != left.end() || riter != right.end()) {
int s = *liter + *riter + carry;
carry = s / 16;
sum.insertTail(s % 16);
++liter;
++riter;
}
if(carry) sum.insertTail(carry);
return sum;
}
LList multiply(const LList& left, const LList& right) {
LList prodSum;
auto leftNode = left.begin();
int zeros = 0;
for(;;) {
if(leftNode == left.end()) break;
int lval = *leftNode;
LList curList;
for(int i = 0; i < zeros; i++) {
curList.insertTail(0);
}
auto rightNode = right.begin();
int carry = 0;
while(rightNode != right.end()) {
int rval = *rightNode;
int product = lval * rval + carry;
carry = product / 16;
product %= 16;
curList.insertTail(product);
++rightNode;
}
while(carry) {
curList.insertTail(carry % 16);
carry /= 16;
}
prodSum = add(prodSum, curList);
++leftNode;
++zeros;
}
return prodSum;
}
int main() {
LList a("111");
LList b("333");
LList c = multiply(a, b); // 36963
std::cout << c.get_digits() << '\n';
}
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