多个 .cpp 文件中包含的头文件

Question

我遵循了一个简单的例子，如下所示。但编译失败。

您能看一下并给我一些建议吗？

使用vs2010控制台应用程序。谢谢。

错误消息

pgm.h(11): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
pgm.h(11): error C2143: syntax error : missing ',' before '&'
1>  multi_fct.cpp
pgm.h(11): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
pgm.h(11): error C2143: syntax error : missing ',' before '&'
1>  ch3_p96.cpp
pgm.h(11): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
pgm.h(11): error C2143: syntax error : missing ',' before '&'
ch3_p96.cpp(24): error C2664: 'prn_info' : cannot convert parameter 1 from 'const char [8]' to 'const int'
1>          There is no context in which this conversion is possible
ch3_p96.cpp(26): error C3861: 'fct1': identifier not found

pgm.h

#include <iostream>
#include <cstdlib>
#include <string>

#define     N   3

void fctl(int k);
void fct2();
void prn_info(const string& pgm_name);

ch3_p96.cpp

#include "stdafx.h"

#include <iostream>

#include "pgm.h"

using namespace std;

int main()
{
    char ans;
    int  k, n = N;

    cout << "This program does not do very much.\n";
    cout << "Do you want more information?\n";
    cout << "Enter either y or Y is yes.\n" << endl;

    cin >> ans;

    if (ans == 'y' || ans == 'Y')
        prn_info("ch3_p96");    // multi_main
    for (k = 0; k < n; ++k)
        fct1(k);

    cout << "Best Regards!" << endl;

}

multi_fct.cpp

#include "StdAfx.h"

#include <iostream>
#include "pgm.h"

using namespace std;

void fct1(int n)
{
    int i;

    cout << "Hello from fct1()" << endl;
    for (i = 0; i < n; ++i)
        fct2();
}

void fct2()
{
    cout << "Hello from fct2()" << endl;

}

multi_prn.cpp

#include "StdAfx.h"

#include <iostream>
#include <string>
#include "pgm.h"

using namespace std;

void prn_info(const string& pgm_name)
{
    cout << "Usage:  " << pgm_name << endl;
    cout << "This program illustrates a   " << endl;
    cout << "Program is more than one file.    " << endl;
    cout << "In this example, a single" << endl;
    cout << ".h file is included at the" << endl;
    cout << "top of our three .cpp files." << endl;
    cout << "Thus pgm.h acts as the \"glue\"" << endl;
    cout << "that binds the program." << endl;
}

Answer 1

您需要命名空间限定字符串：std::string。

编译器错误表示它没有找到类型名称，因此猜测 string 是 int，并继续尝试解析您的代码。

另外，在一个地方使用 fctl （fct 小写-L），在一个地方使用 fct1 （fct one）。

Answer 2

您需要限定字符串：

void prn_info(const std::string& pgm_name);

它位于 std 命名空间中。请不要在头文件中使用using namespace std。