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C++ 为什么我的程序最多只能编译16条记录?_C++_Arrays_Oop_File Io_Time - Fatal编程技术网

C++ 为什么我的程序最多只能编译16条记录?

C++ 为什么我的程序最多只能编译16条记录?,c++,arrays,oop,file-io,time,C++,Arrays,Oop,File Io,Time,下面是我的程序,它应该创建一个对象数组,然后告诉我。每个循环运行所需的时间。循环只是从文件和内存中读/写,程序应该在完成时比较这些方法。由于某些原因,程序仅在创建的记录数为16或更少时显示时间。我似乎不知道为什么。我也不明白为什么我的比率不起作用。可能是因为每个变量都不到一秒钟,所以它试图用0除以0,也许 #include <iostream> #include <fstream> #include <string> #include <ctime>

下面是我的程序,它应该创建一个对象数组,然后告诉我。每个循环运行所需的时间。循环只是从文件和内存中读/写,程序应该在完成时比较这些方法。由于某些原因,程序仅在创建的记录数为16或更少时显示时间。我似乎不知道为什么。我也不明白为什么我的比率不起作用。可能是因为每个变量都不到一秒钟,所以它试图用0除以0,也许

#include <iostream>
#include <fstream>
#include <string>
#include <ctime>
#include <iomanip>
using namespace std;

class TestRecord
{
private:
int _number;
string _data;
public:
TestRecord ()
{_number = 0; _data = "no data";}

TestRecord (int number, string data)
{_number = number; _data = data;}

void setNumber (int number)
{_number = number;}

void setData (string data)
{_data = data;}

int getNumber() const
{return _number;}

string getData() const
{return _data;}

friend ostream &operator <<(ostream &out, TestRecord &records)
{
    out << records._number << " " << records._data;
    return out;
}
};

int main ()
{
    string string256 = "AaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronAaronA";
int recordsToBeCreated = 0;

cout << " How many records should be created?" << endl;
cin >> recordsToBeCreated;

TestRecord* recordObj = new TestRecord[recordsToBeCreated]; 

//--------------------------------------writing

clock_t startTime1 = clock();
for (int count = 0; count < recordsToBeCreated; count++)  //fill object array
{
    srand(count);
    recordObj[count].setData(string256);
    recordObj[count].setNumber(rand()% 10000 + 1000);

}
clock_t endTime1 = clock();
ofstream outFile;

clock_t startTime2 = clock();
for (int count1 = 0; count1 < recordsToBeCreated; count1++) //write to disk
{
    outFile.open("data.txt");
    outFile << recordObj[count1] << endl;
}
clock_t endTime2 = clock();
outFile.close();
//----------------------------------------reading
clock_t startTime3 = clock();
for(int count2 = 0; count2 < recordsToBeCreated; count2++) //read/write from mem
{
    int *tempNumber = new int;
    string *tempString = new string;

    *tempNumber = recordObj[count2].getNumber();
    *tempString = recordObj[count2].getData();

    delete tempNumber;
    delete tempString;
}
clock_t endTime3 = clock();
ifstream inFile;
clock_t startTime4 = clock();
for(int count3 = 0; count3 < recordsToBeCreated; count3++) //read/write from disk
{
    int *tempNumber = new int;
    string *tempString = new string;
    inFile.open("data.txt");

    inFile >> *tempNumber;
    inFile >> *tempString;

    delete tempNumber;
    delete tempString;
}
clock_t endTime4 = clock();
inFile.close();
//---------------------------------random reading comp

int randomNumber = rand()%recordsToBeCreated;

clock_t startTime5 = clock(); //traverse array to random index
for(int count4 = 0; count4 > randomNumber; count4++)
{
    recordObj[count4];
}
clock_t endTime5 = clock();

clock_t startTime6 = clock();
inFile.open("data.txt");
for(int count5 = 0; count5 < randomNumber; count5++)
{
    string *tempString = new string;
    cin.ignore();
    inFile >> *tempString;
}
clock_t endTime6 = clock();
inFile.close();

double seconds1 = endTime1 - startTime1;
seconds1 = seconds1 / CLOCKS_PER_SEC;
double seconds2 = endTime2 - startTime2;
seconds2 = seconds2 / CLOCKS_PER_SEC;
double seconds3 = endTime3 - startTime3;
seconds3 = seconds3 / CLOCKS_PER_SEC;
double seconds4 = endTime4 - startTime4;
seconds4 = seconds4 / CLOCKS_PER_SEC;
double seconds5 = endTime5 - startTime5;
seconds5 = seconds5 / CLOCKS_PER_SEC;
double seconds6 = endTime6 - startTime6;
seconds6 = seconds6 / CLOCKS_PER_SEC;

cout << "Time to write to memory:                      " << fixed << setprecision (5) << seconds1 << " seconds" << endl;
cout << "Time to write to file:                        " << setprecision (5) << seconds2 << " seconds" <<  endl;
cout << "Ratio of (write to disk)/(write to memory):   " << seconds2/seconds1 <<  endl;
cout << "\n\n";
cout << "Runtime to read from memory:                  " << setprecision (5) << seconds3 << " seconds" <<  endl;
cout << "Runtime to read from disk:                    " << setprecision (5) << seconds4 << " seconds" <<  endl;
cout << "Ratio of (read from disk)/(read from memory): " << seconds4/seconds3 << endl;
cout << "\n\n";
cout << "Runtime to find random index from memory:     " << setprecision (5) << seconds5 << " seconds" <<  endl;
cout << "Runtime to find random line from disk:        " << setprecision (5) << seconds6 << " seconds" <<  endl;
cout << "Ratio of (read from disk)/(read from memory): " << seconds6/seconds5 << endl;



delete [] recordObj;
system("pause");
return 0;
#包括
#包括
#包括
#包括
#包括
使用名称空间std;
类测试记录
{
私人:
整数;
字符串数据;
公众:
测试记录()
{{u number=0;_data=“无数据”}
TestRecord(整数、字符串数据)
{{u number=number;{u data=data;}
无效集合编号(整数编号)
{{u number=number;}
void setData(字符串数据)
{{u data=data;}
int getNumber()常量
{返回_数;}
字符串getData()常量
{返回_数据;}
friend ostream&运算符*tempString;
}
clock_t endTime6=时钟();
infle.close();
双秒1=结束时间1-开始时间1;
秒1=秒1/秒时钟;
双秒2=结束时间2-开始时间2;
秒2=秒2/秒时钟;
双秒3=结束时间3-开始时间3;
秒3=秒3/秒时钟;
双秒4=结束时间4-开始时间4;
秒4=秒4/秒时钟;
双秒5=结束时间5-开始时间5;
秒5=秒5/秒时钟;
双秒6=结束时间6-开始时间6;
秒6=秒6/秒时钟;
无法编辑:

这条线

for(int count4 = 0; count4 > randomNumber; count4++)
这是危险的。你不会进入无限循环,只是因为
count4
迟早会缠绕
2^32-1
,但这是一个坏条件。它不应该是第4个计数吗

编辑2:

tempInt/tempString的分配只能执行一次(在循环之前),而不能在循环本身中执行

老东西:

第一个(相当明显的)建议:停止动态分配所有内容

而不是

for(int count2 = 0; count2 < recordsToBeCreated; count2++) //read/write from mem
{
   int *tempNumber = new int;
   string *tempString = new string;

   *tempNumber = recordObj[count2].getNumber();
   *tempString = recordObj[count2].getData();

   delete tempNumber;
   delete tempString;
}
您可以在每次迭代时覆盖该文件。我想这应该是

outFile.open("data.txt");
// write 'em all
for (int count1 = 0; count1 < recordsToBeCreated; count1++)
{
    outFile << recordObj[count1] << endl;
}
outFile.open(“data.txt”);
//都写下来
对于(int count1=0;count1>*临时字符串;
删除临时编号;
删除临时字符串;
}
再次打开“data.txt”,因此只读取第一行

这应该是(删除分配后)

infle.open(“data.txt”);
对于(int count3=0;count3>临时编号;
填充>>临时字符串;
}

请提供更多信息。如果数字大于16,会发生什么情况?它会崩溃吗?打印错误?天哪。请摆脱所有这些指针和手动分配。它们完全没有必要,而且使代码更加复杂和容易出错。@KonradRudolph:这显然是个初学者。你会让他/她跳过基础知识,一切都依靠图书馆吗?指出替代方案很好,但我不会因为这个人学习实际工作原理而责怪他。代码在我看来很好。在ideone上似乎运行正常:我能想到的唯一问题是,如果它无法写入文件(就像在ideone上一样),我的作业需要动态分配。程序差不多完成了,只是数字大于16,什么也没发生。16或更少,并打印处理所有内容所需的时间。我用Visual C++ 2010,如果有帮助的话。我修复了文件覆盖,但我仍然有同样的问题,没有任何事情发生时,我输入17或更多。教师要求分配,以熟悉指针。
for (int count1 = 0; count1 < recordsToBeCreated; count1++)
{
    outFile.open("data.txt");
    outFile << recordObj[count1] << endl;
}
outFile.open("data.txt");
// write 'em all
for (int count1 = 0; count1 < recordsToBeCreated; count1++)
{
    outFile << recordObj[count1] << endl;
}
for(int count3 = 0; count3 < recordsToBeCreated; count3++) //read/write from disk
{
   int *tempNumber = new int;
   string *tempString = new string;
   inFile.open("data.txt");

   inFile >> *tempNumber;
   inFile >> *tempString;

   delete tempNumber;
   delete tempString;
}
inFile.open("data.txt");
for(int count3 = 0; count3 < recordsToBeCreated; count3++) //read/write from disk
{
   int tempNumber;
   string tempString;

   inFile >> tempNumber;
   inFile >> tempString;
}