Question

我正在尝试将库存系统读入结构数组。当我调用该函数并且它到达第一行时我尝试将数据写入数组，我收到错误：

Lab 09.exe中0x777CA932处的未处理异常：Microsoft C ++异常：内存位置0x00F3DC68处的std :: out_of_range。

这是结构：

struct inventory {

int record;
string toolname;
int quantity;
double cost;

};

数组声明：

inventory unsortedArray[100];

这是函数（假设文件的第一行是83 #Electric Sander＃7 57.00）：

void fillArray(inventory unsortedArray[]) {

ifstream file;
string line;
string delim = "#";
stringstream ss;
file.open("records.txt");
int i = 0;

while (!file.eof()) {

    getline(file, line);

    unsigned first = line.find_first_of(delim);
    unsigned last = line.find_last_of(delim);

    unsortedArray[i].toolname = line.substr(first, (last - first) + 1);

    line.erase(first, (last - first) + 1);

    ss << line;
    ss >> unsortedArray[i].record;
    ss >> unsortedArray[i].quantity;
    ss >> unsortedArray[i].cost;

    i++;
    }

    file.close();

}

Answer 1

问题1

使用

*ngIf="myFlag"

通常会导致问题。见Why is iostream::eof inside a loop condition considered wrong?

问题2

使用正确的类型来捕获while (!file.eof())和std::string::find_first_of的返回值。

使用

std::string::find_last_of

或

auto first = line.find_first_of(delim);
auto last = line.find_last_of(delim);

问题3

在继续使用之前，请务必检查std::string::size_type first = line.find_first_of(delim); std::string::size_type last = line.find_last_of(delim);和std::string::find_first_of的返回值。

std::string::find_last_of

我的建议

使用

auto first = line.find_first_of(delim);
auto last = line.find_last_of(delim);

if ( first == std::string::npos )
{
  // Didn't find it. Figure out what to do.
}

if ( last == std::string::npos )
{
  // Didn't find it. Figure out what to do.
}

// Both checks are done. Now you can use first and last.

从文件填充数组时，Visual Studio将中止

1 个答案:

问题1

问题2

问题3