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key9 · Guest

Hi all
I wrote some source code to study,

but I have problem: If I wrote the implement code to .h file directly

code can pass the complie, if I put the code to .cpp file ,it fails , why?

Here's the source code:

[key9@localhost unit]$ gcc -o test test.cpp -lstdc++
/home/key9/tmp/ccgdxJIB.o(.text+0x1c2): In function `main':
: undefined reference to `LinuxTestTerminal::printch(char*)'
/home/key9/tmp/ccgdxJIB.o(.gnu.linkonce.t._ZN17LinuxTestTerminalC1Ev+0x19):
In function `LinuxTestTerminal::LinuxTestTerminal()':
: undefined reference to `vtable for LinuxTestTerminal'
collect2: ld returned 1 exit status

Source code:
********/Terminal.h/*********
#ifndef __TERMINAL_H_
#define __TERMINAL_H_

class Terminal{ // this is virtual class of terminal
public:
virtual void printch(char*) =0;
virtual void backSpace() = 0;
virtual void printCR() = 0;
virtual void printTab() =0;
private:
};
#endif // __TERMINAL_H_

********/LinuxTerminal.h/*********
#ifndef __LINUXTESTTERMINAL_H_
#define __LINUXTESTTERMINAL_H_

#include "Terminal.h"

class LinuxTestTerminal : public Terminal{
public:
void printch(char*);
void backSpace();
void printCR();
void printTab();
};

#endif //__LINUXTESTTERMINAL_H_

********/LinuxTerminal.cpp/*********
#include <stdio.h>
#include "Terminal.h"

void
LinuxTestTerminal::printch(char* ch){
printf("%c",*ch);
}

void
LinuxTestTerminal::backSpace(){
printf("/b");
}

void
LinuxTestTerminal::printCR(){
printf("/n");
}

void
LinuxTestTerminal::printTab(){
printf(" ");
}

********/test.cpp/*********
//use -lstdc++

#include <stdio.h>
#include <termios.h>
#include <unistd.h>
#include <iostream>

#include "Terminal.h"
#include "LinuxTerminal.h"

class Terminal;

using namespace std;

int mygetch( ) {
struct termios oldt,newt;
int ch;
tcgetattr( STDIN_FILENO, &oldt );
newt = oldt;
newt.c_lflag &= ~( ICANON | ECHO );
tcsetattr( STDIN_FILENO, TCSANOW, &newt );
ch = getchar();
tcsetattr( STDIN_FILENO, TCSANOW, &oldt );
return ch;
}

int main(int argc, char *argv[])
{

printf("new line of doing test");

LinuxTestTerminal lt;
lt.printch("dsadadasdasd");

while(mygetch());

}

*********************************
another /LinuxTerminal.h/, delete the LinuxTerminal.cpp file

#ifndef __LINUXTESTTERMINAL_H_
#define __LINUXTESTTERMINAL_H_

#include "Terminal.h"

class LinuxTestTerminal : public Terminal{
public:
void printch(char* ch){
printf("%c",*ch);

}
void backSpace(){
printf("/b");

}
void printCR(){
printf("/n");
}
void printTab(){
printf(" ");
}

};

#endif //__LINUXTESTTERMINAL_H_

Ian Collins · Guest

key9 wrote: