我正在尝试将已编写的程序分解为两个源文件,但在链接它们时遇到问题,并且错误消息对我来说没有任何意义。
我将提供包含相关信息的文件的缩短版本:
//grandiose.cpp:
#include "thingy.h"
int main() {}
//thingy.h:
#include<string>
int add (int x, int y);
char * parse_input_fragment(const string & ,const string & , size_t &, size_t &);
//thingy.cpp:
#include "thingy.h"
int add (int x, int y)
{
return x+y;
}
char * parse_input_fragment(const string & objective,const string & input, size_t & first_finder, size_t & second_finder) {
char * string_to_int_buffer = new char[64];
first_finder = input.find(objective, first_finder);
first_finder = (input.find('=', first_finder))+1;
second_finder = input.find(';', first_finder);
int y = 0;
for(unsigned int x = first_finder; x < second_finder; x++) {
if ( (input[x] != ' ') && (input[x] != '\n') ) {
string_to_int_buffer[y] = input[x];
y++;
}
}
string_to_int_buffer[y] = '\0';
first_finder = second_finder;
return string_to_int_buffer;
}
如果我将 parse_input_fragment 函数放入 grandiose.cpp 中,它可以正常编译,但是当我按照描述将其拆分时,我会收到错误消息。我出于测试目的添加了“add”函数,该函数编译得很好。
我收到的错误消息是针对 thingy.h 中的原型(prototype): 错误 C4430:缺少类型说明符 - 假定为 int。注意:C++ 不支持default-int
它被明确标记为字符指针返回类型,并且在不从 grandiose.cpp 中拆分出来时可以工作,所以我对这里的问题感到非常困惑。
编辑:
好的,移动 using 命名空间 std 后;到适当的位置并按照建议包含 header 防护装置,这些错误消息消失了,但我收到了新的消息,我对此感到更加困惑。我将包含完整的文件和错误消息。
错误消息: Province.obj:错误LNK2005:“public:__thiscall省::province(void)”(??0province@@QAE@XZ)已在grandiose.obj中定义
province.obj:错误LNK2005:“公共(public):__thiscall省::省(class std::basic_string,class std::allocator>,int * const)”(??0province@@QAE@V?$basic_string@ DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAH@Z) 已在 grandiose.obj 中定义
// grandiose.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <vector>
#include <ctime>
#include <iostream>
#include <fstream>
#include <string>
#include "market.h"
int _tmain(int argc, _TCHAR* argv[])
{
market England;
ifstream reader;
reader.open ("provinces.txt", ios::in);
if (reader.is_open()) { //check if txt file successfully opened
cout << "\n\nprovinces.txt was successfully opened.\n\n";
}
else {
cout << "\n\nfile was not successfully opened.\n\n";
return (1);
}
string reader_buffer;
while ( reader.good() ) { // while not end of file
getline (reader, reader_buffer, '}'); // get one province's worth of data from txt file
if (!reader_buffer.empty()) {
parse_provinces (reader_buffer); // send data to be parsed
}
}
add(1,2);
return 0;
}
//market.h
#include <iostream>
#include <list>
#include "province.h"
using namespace std;
class market
{
public:
list<province> provinces;
};
//province.h
#ifndef PROVINCE_H
#define PROVINCE_H
#include <iostream>
#include <string>
using namespace std;
int add (int x, int y);
char * parse_input_fragment(const string & ,const string & , size_t &, size_t &);
class province
{
public:
province::province();
province::province(string, int[]);
unsigned int * rural_poor;
unsigned int * urban_poor;
unsigned int * max_mine_jobs;
unsigned int * max_farm_jobs;
unsigned int * employed_mine;
unsigned int * employed_farm;
unsigned int * employed_factory;
string name;
};
province::province () {
rural_poor = new unsigned int(0);
urban_poor = new unsigned int(0);
max_mine_jobs = new unsigned int(0);
max_farm_jobs = new unsigned int(0);
employed_mine = new unsigned int(0);
employed_farm = new unsigned int(0);
employed_factory = new unsigned int(0);
name = "";
}
province::province (string name, int numbers[]) {
province::name = name;
cout << "This province is named " << province::name << endl;
rural_poor = new unsigned int(numbers[0]);
cout << "Rural poor = " << *rural_poor << endl;
urban_poor = new unsigned int(numbers[1]);
cout << "Urban poor = " << *urban_poor << endl;
max_mine_jobs = new unsigned int(numbers[2]);
cout << "Max mine jobs = " << *max_mine_jobs << endl;
max_farm_jobs = new unsigned int(numbers[3]);
cout << "Max farm jobs = " << *max_farm_jobs << endl;
}
province * parse_provinces(string);
#endif
//province.cpp
#include "stdafx.h"
#include "province.h"
int add (int x, int y)
{
return x+y;
}
char * parse_input_fragment(const string & objective,const string & input, size_t & first_finder, size_t & second_finder) {
char * string_to_int_buffer = new char[64];
first_finder = input.find(objective, first_finder);
first_finder = (input.find('=', first_finder))+1;
second_finder = input.find(';', first_finder);
int y = 0;
for(unsigned int x = first_finder; x < second_finder; x++) {
if ( (input[x] != ' ') && (input[x] != '\n') ) {
string_to_int_buffer[y] = input[x];
y++;
}
}
string_to_int_buffer[y] = '\0';
first_finder = second_finder;
return string_to_int_buffer;
}
province * parse_provinces(string input) {
size_t first_finder;
size_t second_finder;
char * string_to_int_buffer;
int population_info[4];
// find the name
first_finder = input.find('=');
string name;
for(unsigned int x = 0; x < first_finder; x++) {
if ((input[x] != ' ') && (input[x] != '\n')) {
name.push_back(input[x]);
}
}
// find the rural poor
string_to_int_buffer = parse_input_fragment("rural_poor", input, first_finder, second_finder);
population_info[0] = atoi(string_to_int_buffer);
// find the urban poor
string_to_int_buffer = parse_input_fragment("urban_poor", input, first_finder, second_finder);
population_info[1] = atoi(string_to_int_buffer);
// find max mine jobs
string_to_int_buffer = parse_input_fragment("max_mine_jobs", input, first_finder, second_finder);
population_info[2] = atoi(string_to_int_buffer);
// find max farm jobs
string_to_int_buffer = parse_input_fragment("max_farm_jobs", input, first_finder, second_finder);
population_info[3] = atoi(string_to_int_buffer);
delete[] string_to_int_buffer;
string_to_int_buffer = NULL;
province * current_province = new province(name, population_info);
return current_province;
}
最佳答案
即使您包含 <string>
,您还需要使用std
命名空间来访问 string
类型:
#include<string>
using namespace std;
类型string
驻留在 std 命名空间中,因此只需输入 string
不会命名已知类型。
或者,您可以替换所有出现的 string
与 std::string
在标题中并使用 using
.cpp 中的语句(实际上这是理想的处理方式,因为它避免了所有 std
函数和类型对全局命名空间造成污染。
Jason 的回答也是一个很好的建议:使用包含保护来保护你的头文件,因此如果你两次包含相同的头文件(例如间接),你将不会因为多个定义而出现编译器错误(C++ 有一个单定义规则) :所有类只能定义一次)。在您的具体情况下,这不是问题,但养成这样做的习惯以避免以后的问题是一件好事
关于c++ - 链接源文件,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/10365704/