C ++清单项目删除 [英] C++ inventory item removal
本文介绍了C ++清单项目删除的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
- 将库存增加到10个项目。 DONE !!!
- 创建一个for循环，要求用户输入库存中的初始项目。
- 循环创建一个小故事，治疗师改变两个项目（即项目4和8）。我想要的是SWAP一个项目的另一个项目，即，你想交易你的{item [item2] y或n
-
- 按字母顺序对库存进行排序。您可以根据需要使用自己的排序，但这里是一个冒泡排序算法：
// A simple inventory program using a struct to store data
// in an array.
#include <cstdlib>
#include <iostream>
#include <iomanip>
#include <fstream>
#include <string>
#include <sstream>
using namespace std;
// define a data structure
struct InventoryRecord
{
string name; // inventory item name
int qty; // how many are in stock
double value; // the value
};
// const for the max size of the record array
const int MAX_SIZE = 9;
// function prototypes
void addData(InventoryRecord list[], int& size);
void dispData(const InventoryRecord list[], int size);
void remData( const InventoryRecord list[], int size);
void saveFile(const InventoryRecord list[], int size);
void openFile(InventoryRecord list[], int& size);
char getMenuResponse();
int main(int argc, char *argv[])
{
InventoryRecord recList[MAX_SIZE];
int numOfRecs = 0;
bool run = true;
do
{
cout << "Hero's Inventory - " << numOfRecs << " items in your bag" << endl;
switch ( getMenuResponse() )
{
case 'A': addData(recList, numOfRecs); break;
case 'D': dispData(recList, numOfRecs); break;
case 'R': remData(recList, numOfRecs); break;
case 'O': openFile(recList, numOfRecs); break;
case 'S': saveFile(recList, numOfRecs); break;
case 'Q': run = false; break;
default : cout << "That is NOT a valid choice" << endl;
}
} while (run);
cout << endl << "Program Terminated" << endl;
// system("PAUSE"); // Program exits immediatly upon "Quit" if commented out
return EXIT_SUCCESS;
}
// Task: Allow data entry of one inventory item
// Accepts: References to the inventory array and its size
// Returns: Nothing
// Modifies: The array and size 'actual parameter'
// NOTE: Could be modified to allow entry of more than one item
void addData(InventoryRecord list[], int& size)
{
InventoryRecord tmp; // declare a temp item that we will load before putting in the array
char response;
char str[256]; // needed for cin.getline; we are going to use a char array
if (size < MAX_SIZE) {
system("cls");
cout << "Please enter 10 items helpful to your quest! " << endl;
cout << "Enter item: " << endl << endl;
cout << "Name: ";
// Get up to 256 characters from the keyboard including white space.
// Stop reading if encounter the \n first. If there's any chance of
// more than 256 characters you will have to clean up cin with
// cin.ignore before the next input.
cin.getline(str, 256, '\n'); // for char arrays; different from the other getline
tmp.name = str;
cout << "Quantity: ";
cin >> tmp.qty;
cout << "Value: ";
cin >> tmp.value;
cout << endl;
// see if this record should be added to the array
cout << "Add to inventory? (y/n) ";
cin >> response;
if (toupper(response) == 'Y')
list[size++] = tmp;
} else {
cout << "Inventory is full; cannot enter more units." << endl;
system("pause");
}
system("cls");
}
void dispData(const InventoryRecord list[], int size)
{
system("cls");
double cost = 0;
if(size < 1) {
cout << "Nothing to display" << endl;
} else {
cout << "All Items in your Bag" << endl << endl;
cout << fixed << setprecision(2);
cout << "Item Name Qty Value" << endl;
cout << "~~~~~~~~~~~~~~~~~~" << endl;
cout << left;
for (int i = 0; i < size; i++) {
cout << setw(21) << list[i].name << right
<< setw(4) << list[i].qty
<< setw(10) << list[i].value << left << endl;
cost = cost + list[i].value * list[i].qty;
}
cout << "~~~~~~~~~~~~~~~~~~~" << endl;
cout << right << setw(3) << size;
cout << " items listed";
cout << right << setw(19) << cost << endl << endl;
}
system("PAUSE");
system("cls");
}
void remData(const InventoryRecord list[], int size) {
system("cls");
cout <<"Enter Item you wish to remove from your inventory: " << endl;// This is being displayed so user can see items in the inventory
double cost = 0;
if(size < 1) {
cout << "Nothing to display" << endl;
} else {
cout << "All Items in your Bag" << endl << endl;
cout << fixed << setprecision(2);
cout << "Item Name Qty Value" << endl;// It is not displaying right the alignment is off
cout << "~~~~~~~~~~~~~~~~~~" << endl;
cout <<"Item Name: ";/* from here I do not know what to do! What I want is have use type the item name they want removed
also display an error if they enter an item wrong*/
cout << left;
for (int i = 0; i < size; i++) {
cout << setw(21) << list[i].name << right
<< setw(4) << list[i].qty
<< setw(10) << list[i].value << left << endl;
cost = cost + list[i].value * list[i].qty;
}
cout << "~~~~~~~~~~~~~~~~~~~" << endl;
cout << right << setw(3) << size;
cout << " items listed";
cout << right << setw(19) << cost << endl << endl;
}}
// Save records to disc
void saveFile(const InventoryRecord list[], int size) {
ofstream outfi("Inventory.txt");
// make sure the file stream is open before doing IO
if (!outfi.fail()) {
system("cls");
cout << "Saving inventory to the disc ";
for(int i = 0; i < size; i++) {
outfi << list[i].name << ';'
<< list[i].qty << ';'
<< list[i].value;
// Start a new line after all but the last record
// Simplifies reading the file as EOF is at end of last line
if (i < size-1) outfi << endl;
}
cout << endl << size << " records writen to the disc." << endl;
outfi.close();
system("PAUSE");
system("cls");
}
else {
cout << "ERROR: problem with file" << endl;
system("PAUSE");
system("cls");
}
}
// Open file and load array
void openFile(InventoryRecord list[], int& size)
{
ifstream infi("Inventory.txt");
string str;
stringstream strstrm;
// make sure the file stream is open before doing IO
if (!infi.fail()) {
system("cls");
cout << "Reading inventory from the disc ";
size = 0; // overwrite any existing records
while(!infi.eof() && size < MAX_SIZE) {
// get and store the name
getline(infi, str, ';');
list[size].name = str;
// get, convert and store the quantity
getline(infi, str, ';');
strstrm.str(""); strstrm.clear(); // empty and clear the stringstream
strstrm << str;
strstrm >> list[size].qty;
// get, convert and store the cost
getline(infi, str);
strstrm.str(""); strstrm.clear(); // empty and clear the stringstream
strstrm << str;
strstrm >> list[size++].value;
}
cout << endl << size << " records read from the disc." << endl;
system("PAUSE");
system("cls");
}
else { // something went wrong with opening the file
cout << "ERROR: problem with file" << endl;
system("PAUSE");
system("cls");
}
}
char getMenuResponse()
// Task: Put the menu on screen and get a response
// Accepts: Nothing
// Returns: The users response
// Modifies: Nothing
// NOTE: Characters are far more intuitive at the command
// line than numbers; avoid using numbers.
{
char response;
cout << endl << "Make your selection" << endl
<< "(A)dd Items, (D)isplay Items, (R)emove items, (O)pen File, (S)ave File, (Q)uit" << endl
<< "> ";
cin >> response;
cin.ignore(256, '\n');
// clean-up up to 256 chars including the delimiter specified (\n, the endl)
// OR stop when the \n is encountered after removing it.
return toupper(response);
}
推荐答案
基本上两种方法来删除元素，最简单的是用最后一个删除的元素，并调整列表大小：
There are essentially two ways to remove the element, the easiest is swap the element which you want to delete with the last one and resize the list:
void deleteElem(Data[] list, int & listLength, int ix) {
if (ix < listLength - 1) {
list[ix] = list[listLength - 1];
}
--listLength;
}
第二个解决方案是在向左删除元素后，
The second solution is memmove everthing after the to deleting element one to the left:
void deleteElem(Data[] list, int & listLength, int ix) {
memmove(list[ix], list[ix + 1], (listLength - ix - 1) * sizeof(Data));
--listLength;
}
编辑：memmove的长度有一个错误，您应该阅读文档。
There was an error in the length for memmove, always the same. You should read the documentation.
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