C ++中的简单“数据库" [英] Simple 'database' in c++
问题描述
我的任务是用c ++创建伪数据库.给出了3个表，分别存储名称(char *)，年龄(int)和性别(布尔).编写允许以下操作的程序:
-将新数据添加到表中
-显示所有记录
-使用条件对表格进行排序:
-名称增加/减少
-年龄增加/减少
-性爱
My task was to create pseudodatabase in c++. There are 3 tables given, that store name(char*), age(int), and sex (bool). Write a program allowing to :
- add new data to the tables
- show all records
- sort tables with criteria :
- name increasing/decreasing
- age increasing/decreasing
- sex
必须使用功能模板.数组的大小也必须是可变的，具体取决于记录的数量.
Using function templates is a must. Also size of arrays must be variable, depending on the amount of records.
我有一些代码，但是那里仍然有问题. 这是我所拥有的: 函数tabSize()用于返回数组的大小.但是目前它返回的是我猜想的指针大小:
I have some code but there are still problems there. Here's what I have: Function tabSize() for returning size of array. But currently it returns size of pointer I guess :
#include <iostream>
using namespace std;
template<typename TYPE> int tabSize(TYPE *T)
{
int size = 0;
size = sizeof(T) / sizeof(T[0]);
return size;
}
如何使其返回数组的大小，而不是其指针?
How to make it return size of array, not its pointer ?
接下来最重要的是:add()用于添加新元素.首先在里面，我得到数组的大小(但是因此它返回指针的值，而不是大小，它现在已经没有用了:/).然后，我认为我必须检查数据类型是否为char.还是我错了?
Next the most important : add() for adding new elements. Inside first I get the size of array (but hence it returns value of pointer, and not size it's of no use now :/). Then I think I must check if TYPE of data is char. Or am I wrong ?
// add(newElement, table)
template<typename TYPE> TYPE add(TYPE L, TYPE *T)
{
int s = tabSize(T);
//here check if TYPE = char. If yes, get the length of the new name
int len = 0;
while (L[len] != '\0') {
len++;
}
//current length of table
int tabLen = 0;
while (T[tabLen] != '\0') {
tabLen++;
}
//if TYPE is char
//if current length of table + length of new element exceeds table size create new table
if(len + tabLen > s)
{
int newLen = len + tabLen;
TYPE newTab = new [newLen];
for(int j=0; j < newLen; j++ ){
if(j == tabLen -1){
for(int k = 0; k < len; k++){
newTab[k] =
}
}
else {
newTab[j] = T[j];
}
}
}
//else check if tabLen + 1 is greater than s. If yes enlarge table by 1.
}
我想在这里正确吗?
我猜最后一个函数show()是正确的:
Last functions show() is correct I guess :
template<typename TYPE> TYPE show(TYPE *L)
{
int len = 0;
while (L[len] == '\0') {
len++;
}
for(int i=0; i<len; i++)
{
cout << L[i] << endl;
}
}
，sort()的问题如下:我可以影响排序是减少还是增加?我在这里使用气泡排序.
and problem with sort() is as follows : Ho can I influence if sorting is decreasing or increasing ? I'm using bubble sort here.
template<typename TYPE> TYPE sort(TYPE *L, int sort)
{
int s = tabSize(L);
int len = 0;
while (L[len] == '\0') {
len++;
}
//add control increasing/decreasing sort
int i,j;
for(i=0;i<len;i++)
{
for(j=0;j<i;j++)
{
if(L[i]>L[j])
{
int temp=L[i];
L[i]=L[j];
L[j]=temp;
}
}
}
}
运行它的主要功能:
int main()
{
int sort=0;
//0 increasing, 1 decreasing
char * name[100];
int age[10];
bool sex[10];
char c[] = "Tom";
name[0] = "John";
name[1] = "Mike";
cout << add(c, name) << endl;
system("pause");
return 0;
}
推荐答案
在您的设计中，您必须具有一个保持数组大小的变量.该值将在添加或删除项目时进行调整. C ++语言不具备获取数组变量大小的功能.
In your design, you must have a variable that maintains the size of the array. This value will be adjusted as items are added or removed. The C++ language has no facilities for obtaining the size of an array variable.
此外，更喜欢使用std::string而不是char *.如果您的讲师说使用char *，则将其作为参数提供给您的函数，但在函数和类内部转换为std::string.这将使您的生活更加轻松.
Also, prefer to use std::string instead of char *. If your instructor says to use char *, then provide it as a parameter to your functions, but convert to std::string inside functions and classes. This will make your life a lot easier.
不要实现自己的排序算法.优先使用std::sort和其他比较功能. std::sort算法已经过测试，可以节省您的时间和精力.
Don't implement your own sort algorithms. Prefer to use std::sort and different compare functions. The std::sort algorithm has been tested and will save you time and effort.
实施Visitor设计模式.这将允许您以不同的方式访问表，而无需在表类中编写新方法.例如，使用Visitor基类，您可以派生用于从文件读取，写入文件和显示内容的类，而无需更改表类.
Implement the Visitor design pattern. This will allow you to access your tables in different ways without writing new methods in the table class. For example, with a Visitor base class, you can derive classes for reading from files, writing to files and displaying content without changing the table class.
最后，请勿使用可能无法携带的system("pause").取而代之的是，可以在std::istream::ignore中找到的cin.ignore.
Lastly, don't use system("pause") which may not be portable. Instead, prefer cin.ignore which can be found in std::istream::ignore.
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