代码： file : addstring.h #include <sstream> #include <string> using namespace::std; class addstring { public: int i ; ostringstream jason; string m_string; string tostring(ostringstream& jason, int na); int test(int a,int b); }; file :addstring.cpp #include <sstream> #include"addstring.h" void addstring::addstring() { jason.str(""); cout < <"ddd" < <endl; string m_string = NULL; } int addstring::test(int a,int b){ cout < <"test" < <endl; } file main.cpp #include <iostream> #include <sstream> #include"addstring.h" #include <string.h> using namespace::std; int main () { addstring add; add.test(1,2); } !! error main.cpp:(.text+0x1c0): undefined reference to `addstring::test(int, int)' collect2: ld returned 1 exit status 简单的代码问题到不少： void addstring::addstring() 构造函数无返回值，并且需要在类中声明，改为 addstring::addstring() class addstring { ...一些定义... addstring();//声明不可少 }; int addstring::test(int a,int b)需要返回一个int类型的值，改为 int addstring::test(int a,int b) { do something.... return 0; } 每个单独的.h文件最好加上下面的代码： #ifndef _addstring_ #define _addstring_ ......类代码...... #endif
