Question

您可以在“使用C ++编程原理实践” 书第348页中检查此代码。没有书写错误，我认为使用相同变量名称“ 名称”时会出错。 或代码顺序顺序。当我运行此代码并要求我输入一个文件名作为输入，输入另一个文件名作为输出时，该程序关闭，没有任何影响或错误。

#include "std_lib_facilities.h"
using namespace std;

// struct Reading
struct Reading {
    int hour;
    double temperature;
    Reading(int h, double t) : hour(h), temperature(t) {}
};

int main()
{
    cout << "Please enter input file name: ";
    string name;
    cin >> name;
    ifstream ist(name.c_str()); // ist reads from the file named "name"

    if (!ist) 
        error("can't open input file ", name);

    cout << "Please enter name of output file: ";
    cin >> name;
    ofstream ost(name.c_str());

    if (!ost) 
        error("can't open output file ", name);

    vector<Reading> temps;
    int hour;
    double temperture;

    while (ist >> hour >> temperture) {
        if (hour < 0 || 23 < hour) 
            error("hour out of range", "While reading");            
        temps.push_back(Reading(hour, temperture));
    }

    for (int i = 0; i < temps.size(); ++i)
        ost << '(' << temps[i].hour << ',' << temps[i].temperature << ")\n";

    return 0;
}

Answer 1

我更改了陈述顺序，输入了：

vector<Reading> temps;
  int hour;
  double temperture;

while (ist >> hour >> temperture) {
    if (hour < 0 || 23 < hour) 
        error("hour out of range", "While reading");            
    temps.push_back(Reading(hour, temperture));
}

这行代码之后...

if (!ist) 
    error("can't open input file ", name);

////完整版

#include "pch.h"
#include "std_lib_facilities.h"
#include <iostream>
#include <string>

using namespace std;
// struct Reading

struct Reading {
    int hour;
    double temperature;
    Reading(int h, double t) : hour(h), temperature(t) {}
};

int main()
{
    cout << "Please enter input file name: ";
    string name;
    cin >> name;
    ifstream ist(name.c_str()); // ist reads from the file named "name"
    if (!ist) error("can't open input file ", name);  

    //why the book typed it here
    vector<Reading>temps;
    int hour;
    double temperture;
    while (ist >> hour >> temperture) {
        if (hour < 0 || 23 < hour) error("hour out of range", "While reading");
        temps.push_back(Reading(hour, temperture));
    }
    //end

    cout << "Please enter name of output file: ";
    cin >> name;
    ofstream ost(name.c_str());
    if (!ost) error("can't open output file ", name);  

    for (int i = 0; i < temps.size(); ++i)
        ost << '(' << temps[i].hour << ','
        << temps[i].temperature << ")\n";
    // output result to console window... modification by me!
    for (int i = 0; i < temps.size(); ++i)
        cout << '(' << temps[i].hour << ','
        << temps[i].temperature << ")\n";

    keep_window_open("quit");

    return 0;
}

////结束

..您必须像这样格式化输入文件：

1 60.6
2 45.5
3 70.5

，输出文件将是：
（1,60.6）
（2,45.5）
.....
还有一个。
谢谢你们对我的帮助！

为什么这段代码给我错误？有自我错误吗？

1 个答案: