c++ - 在 linux 中编译简单的 C++ 程序(第一次)

Question

我在 Linux 中使用 C++ 编译简单程序时遇到错误。有 3 个文件:Employee.h , Employee.cpp, and Salary.cpp (main) .我在 Salary.cpp <iostream>, <fstream>, <string>, <stdio.h>, <stdlib.h> 中包含了几个系统头文件我使用的唯一原因是 itoa()功能。我无法编译它并在某处阅读“”有时是先决条件的地方。
我得到的错误是:'Salary.cpp:195:47: error: itoa was not declared in this scope

现在，我已经将 header 包含在全局范围内，并且 itoa() 仅在我包含的文件中使用，所以除了不包含正确的系统 header 外，我不知道为什么会发生这种情况.我需要在命令行中指定所有系统 header 吗？我不太确定发生了什么。

编辑:这里是一些源代码...我只是扩展了保持简短所需的内容。错误发生在底部附近的 addEmployee() 函数中……我不确定我是否知道如何放置行号。就在create new Employee()之后

#include "Employee.h"

#include <iostream>
#include <fstream>
#include <string>
#include <cstdio>
#include <cstdlib>


void findEmployees(Employee*[], const short);
void addEmployee(Employee*[], short&);
unsigned short parseDataFile(Employee* [], short);
bool insertEmployee(Employee*[], short, Employee*);

int main(int argc, char** argv)
{
    //100 employees max, too lazy to create dynamic container
    Employee* employeeList[100];

    //Parse data file, return the length of the list made
    short listLen = parseDataFile(employeeList, 100);

    //Employee database is built, run query engine
    std::cout << "*************************************************\n";
    std::cout << "This program lets you search for salaries of employees or input new employee information.\n";
    std::cout << "*************************************************\n\n\n";

    char choice = { 0 };
    while (true)
    {
        std::cout << "Please choose an option: \n";
        std::cout << "(1) Search for employee salaries.\n";
        std::cout << "(2) Input new employee data\n";
        std::cout << "(3) Exit\n\n";
        std::cin >> choice;

        switch (choice)
        {

        case '1':
            findEmployees(employeeList, listLen - 1);
            break;

        case '2':
            addEmployee(employeeList, listLen);
            break;

        case '3':
            exit(0);
            break;
        }
    }

    return 0;
}

unsigned short parseDataFile(Employee* empList[], short len)
{
    //Do stuff
}

void findEmployees(Employee* empList[], const short len)
{
    //Do stuff
}

void addEmployee(Employee* empList[], short& len)
{
    char first[32] = "";
    char last[32] = "";
    char salary[32] = "";
    char id[32] = "";
    bool loop = true;

    while (loop)
    {
        std::cout << "Input Last Name:  ";
        std::cin.clear();
        std::cin.sync();
        std::cin.getline(last, 31);
        std::cout << std::endl << std::endl;

        std::cout << "Input First Name:  ";
        //Get user name
        std::cin.clear();
        std::cin.sync();
        std::cin.getline(first, 31);
        std::cout << std::endl << std::endl;

        std::cout << "Input Salary:  $";
        //Get user name
        std::cin.clear();
        std::cin.sync();
        std::cin.getline(salary, 31);
        std::cout << std::endl << std::endl;

        Employee* employee = new Employee();
        employee->setID( itoa((int)len, id, 10) ); //Set id

        employee->setFirstName(first); //Set first name
        employee->setLastName(last); //Set last name
        employee->setSalary(salary); //Set salary

        //Inserts new employee at the end of the list, no real reason to sort the list for this assignment
        //I guess I could have used std::vector to make it easy
        empList[len] = employee;
        ++len; //Increment length of the list

        char yesNo = { 0 };
        std::cout << "Would you like to enter another employee?  (Y, N):  ";
        std::cin >> yesNo;
        std::cout << std::endl << std::endl;
        switch (yesNo)
        {
            case 'Y':
            case 'y':
                //do nothing
            break;

            case 'N':
            case 'n':
                loop = false;
            break;

        }        
    }
}

Answer 1

Linux 不提供itoa 实现。实现相同行为并使用 C++11 的最佳方法是以下列方式使用 std::to_string:

std::string tmp = std::to_string(1);

如果您使用的是较旧的 C++ 版本，则可以使用字符串流:

std::stringstream tmpSS;
tmpSS << 1;
std::string tmp = out.str();

编辑:在提供的示例中，您还需要调用 std::string 的 c_str() 方法:

employee->setID( (char*) tmp.cstr() ); //Set id

其中 tmp 是前面的选项之一。