如何在C ++中将句子保存在文本文件中？

Question

这就是我所拥有的，该程序可以正常运行，我唯一的问题是它不会在File3.txt中保存适当的句子。 我包括了整个程序以进行理解，这是什么原因导致我无法正确执行阻止“ r”选项不保存的句子？ 谢谢。

void ascii (int number);
bool raffle (int number);
const int cArray=5;




int main () 
{       

    int value;

    char option;

while (1)
{


    cout <<"Enter a positive integer number: " <<endl;
    cin >>value;
    cout <<endl;


    cout <<"A[scii]" "\t\tR[affle]" "\t\tE[xit]" <<endl;
    cout <<"Please select an option: " <<endl;
    cin >>option;
    cout<<endl;

    switch (option)
    {
        case 'a':
        case 'A':

            ascii(value);
            break;

        case 'r':
        case 'R':
            ofstream outfile("G:/File3.txt", ios::out);
            if(!outfile)
            {
                cout<<"File could not be opened"<<endl;
                exit(1);
            }
            if (raffle(value)==1)
            {
                outfile<<"The number "<<value<<"is present in the array."<<endl;
            }
            else
            {
                outfile<<"The number "<<value<<"is not present in the array."<<endl;
            }
            outfile.close();
            break;

        case 'e':
        case 'E':

            return 0;
            break;


    }
}
}


void ascii (int value)
{

    if (48 <= value && value <= 57)
    {
        cout <<"The number you have entered corresponds to a digit in the ASCII table." <<endl;
    }
    else if(65 <= value && value <= 90)
    {
        cout <<"The number you have entered corresponds to an uppercase letter in the ASCII table." <<endl;
    }
    else if (97 <= value && value <= 122)
    {
        cout <<"The number you have entered corresponds to a lowercase letter in the ASCII table." <<endl;
    }
    else  
    {
        cout <<"The number you have entered corresponds to none of the above." << endl;
    }

}

bool raffle (int value)
{   
    int random[cArray];
    srand(time(NULL));
    for (int i=0; i<5; i++)
    {
        random[i]= 0+rand()%(100+1-0);
        cout<<random[i]<<" "<<endl;
    }

    for (int j=0; j<5; j++)
    {
        if (value == random[j])
        {
            cout << "\n" <<j<<endl;

            return true;
        }
    }
            cout << "Number not present."<<endl;
            return false;



}

Answer 1

看来您忘记了outfile.open() ..

更新：好的，问题出在这里（一个微妙的问题）。 您不应该在switch case语句中声明ofstream。 而是这样声明它：

    int value;
ofstream outfile("G:/File3.txt", ios::out);
    char option = 'r';


    switch (option)
    {
        case 'r':
        case 'R':

            if(!outfile.is_open())
            {
                cout<<"File could not be opened"<<endl;
                exit(1);
            }
            if (raffle(value)==1)
            {
                outfile<<"The number "<<value<<"is present in the array."<<endl;
            }
            else
            {
                outfile<<"The number "<<value<<"is not present in the array."<<endl;
            }

            break;

case 'e' :
case 'E' :
break;
    }
outfile.close();
return 0;

并且，如果您声明int main（），则始终返回值。修改后的代码的完整版本在此处 。

Answer 2

这是修改后的代码::

#include <iostream>
#include <fstream>
#include <cstdlib>

using namespace std;

void ascii (int number);
bool raffle (int number);
const int cArray=5;

int main ()
{

    int value;

    char option;

while (1)
{


    cout <<"Enter a positive integer number: " <<endl;
    cin >>value;
    cout <<endl;


    cout <<"A[scii]" "\t\tR[affle]" "\t\tE[xit]" <<endl;
    cout <<"Please select an option: " <<endl;
    cin >>option;
    cout<<endl;

    ofstream outfile("./File3.txt", ios::out);

    switch (tolower(option))
    {
        case 'a':

            ascii(value);
            break;
        case 'r':
            if(!outfile)
            {
                cout<<"File could not be opened"<<endl;
                exit(1);
            }
            if (raffle(value)==1)
            {
                outfile<<"The number "<<value<<"is present in the array."<<endl;
            }
            else
            {
                outfile<<"The number "<<value<<"is not present in the array."<<endl;
            }
            outfile.close();
            break;

        case 'e':
                return 0;
            break;


    }
        }

        return 0;
}


void ascii (int value)
{

    if (48 <= value && value <= 57)
    {
        cout <<"The number you have entered corresponds to a digit in the ASCII table." <<endl;
    }
    else if(65 <= value && value <= 90)
    {
        cout <<"The number you have entered corresponds to an uppercase letter in the ASCII table." <<endl;
    }
    else if (97 <= value && value <= 122)
    {
        cout <<"The number you have entered corresponds to a lowercase letter in the ASCII table." <<endl;
    }
    else
    {
        cout <<"The number you have entered corresponds to none of the above." << endl;
    }

}

bool raffle (int value)
{
    int random[cArray];
    srand(time(NULL));
    for (int i=0; i<5; i++)
    {
        random[i]= 0+rand()%(100+1-0);
        cout<<random[i]<<" "<<endl;
    }

    for (int j=0; j<5; j++)
    {
        if (value == random[j])
        {
            cout << "\n" <<j<<endl;

            return true;
        }
    }
            cout << "Number not present."<<endl;
            return false;
}

我认为的问题是只在一个case分支中声明了一个流。这使得变量/流不安全。 该代码在Linux中为我工作

Answer 3

您好，所有帮助我解决此问题的人。 我发现switch和fstream不兼容，因此我将大小写更改为if（）和if（）语句，而不是将我的（raffle（value == 1）更改为（raffle（value ==是），并且再次奏效，谢谢大家的回覆，尤其是Hoong Long！-Maria：D