谁来点拨一下

daniel_zhy

test1.cpp

1. 
   
2. #include <iconv.h>
   
3. #include <iostream>
   
4. 
   
5. using namespace std;
   
6. 
   
7. int main(){
   
8.         char* inbuf=strdup("123456");
   
9. 
   
10.         char* outbuf=(char *)malloc(sizeof(char)*10);
    
11.         memset(outbuf, 0, 10 );
    
12.        
    
13.         cout<<"inbuf_before:"<<inbuf<<endl;
    
14.         cout<<"outbuf_before:"<<outbuf<<endl;
    
15. //        cout<<"&outbuf_before:"<<&outbuf<<endl;
    
16. 
    
17.         size_t inbytesleft=strlen(inbuf);
    
18.         size_t outbytesleft=10;
    
19. 
    
20.         //please take a look following lines
    
21.         //start..
    
22.         iconv_t cd;
    
23.         char **pin = &inbuf;
    
24.         char **pout = &outbuf;
    
25.        
    
26.         cd = iconv_open("utf-8","gbk");
    
27.         memset(outbuf,0,outbytesleft);
    
28.         iconv(cd,pin,&inbytesleft,pout,&outbytesleft);
    
29.         iconv_close(cd);
    
30.         //..end
    
31. 
    
32.         cout<<"inbuf_after:"<<inbuf<<endl;
    
33.         cout<<"outbuf_after:"<<outbuf<<endl;
    
34. //        cout<<"&outbuf_after:"<<&outbuf<<endl;
    
35. 
    
36.         free(inbuf);
    
37.         free(outbuf);
    
38. }
    

复制代码

test2.cpp

1. 
   
2. #include <iconv.h>
   
3. #include <iostream>
   
4. 
   
5. using namespace std;
   
6. 
   
7. void convert(char * inbuf, char* outbuf, size_t inbytesleft, size_t outbytesleft);
   
8. 
   
9. int main(){
   
10.         char* inbuf=strdup("123456");
    
11. 
    
12.         char* outbuf=(char *)malloc(sizeof(char)*10);
    
13.         memset(outbuf, 0, 10 );
    
14.        
    
15.         cout<<"inbuf_before:"<<inbuf<<endl;
    
16.         cout<<"outbuf_before:"<<outbuf<<endl;
    
17. //        cout<<"&outbuf_before:"<<&outbuf<<endl;
    
18. 
    
19.         size_t inbytesleft=strlen(inbuf);
    
20.         size_t outbytesleft=10;
    
21. 
    
22.         //please take a look following lines
    
23.         //start..
    
24.         convert(inbuf, outbuf, inbytesleft, outbytesleft);
    
25.         //..end
    
26. 
    
27.         cout<<"inbuf_after:"<<inbuf<<endl;
    
28.         cout<<"outbuf_after:"<<outbuf<<endl;
    
29. //        cout<<"&outbuf_after:"<<&outbuf<<endl;
    
30. 
    
31.         free(inbuf);
    
32.         free(outbuf);
    
33. }
    
34. 
    
35. //move the convert block to a function.
    
36. void convert(char * inbuf, char* outbuf, size_t inbytesleft, size_t outbytesleft){
    
37.         iconv_t cd;
    
38.         char **pin = &inbuf;
    
39.         char **pout = &outbuf;
    
40.        
    
41.         cd = iconv_open("utf-8","gbk");
    
42.         memset(outbuf,0,outbytesleft);
    
43.         iconv(cd,pin,&inbytesleft,pout,&outbytesleft);
    
44.         iconv_close(cd);
    
45. }
    

复制代码

执行结果为：

1. 
   
2. # g++ -o test1 test1.cpp
   
3. # ./test1
   
4. inbuf_before:123456
   
5. outbuf_before:
   
6. inbuf_after:
   
7. outbuf_after:
   
8. # g++ -o test2 test2.cpp
   
9. # ./test2
   
10. inbuf_before:123456
    
11. outbuf_before:
    
12. inbuf_after:123456
    
13. outbuf_after:123456
    

复制代码

其中test2是期望的结果。

可test1的问题在哪呢？

ywchen2000

还真没有看出来是什么原因,建议用inline

nait

好好看看iconv的manpage,想想为什么函数原型是指向指针的指针
再比较下面两幅图中inbuf和outbuf有什么不同,你最后的free对不对
还有,c语言参数是传值的
如果所有你都搞清楚了就明白你为什么错了

nait

帖一个修正的版本[PHP]#include <iconv.h>
#include <iostream>

using namespace std;

int main(){
        char* inbuf=strdup("123456");

        char* outbuf=(char *)malloc(sizeof(char)*10);
        memset(outbuf, 0, 10 );
       
        cout<<"inbuf_before:"<<inbuf<<endl;
        cout<<"outbuf_before:"<<outbuf<<endl;
//        cout<<"&outbuf_before:"<<&outbuf<<endl;

        size_t inbytesleft=strlen(inbuf);
        size_t outbytesleft=10;

        //please take a look following lines
        //start..
        iconv_t cd;
        char **pin = &inbuf;
        char **pout = &outbuf;
        char *in_bak = inbuf;
        char *out_bak = outbuf;
       
        cd = iconv_open("utf-8","gbk");
        memset(outbuf,0,outbytesleft);
        if (iconv(cd,pin,&inbytesleft,pout,&outbytesleft) == -1){
          perror("iconv");
        }
        iconv_close(cd);
        //..end

        cout<<"inbuf_after:"<<in_bak<<endl;
        cout<<"outbuf_after:"<<out_bak<<endl;
//        cout<<"&outbuf_after:"<<&outbuf<<endl;

        free(in_bak);
        free(out_bak);
}
[/PHP]

pluskid

Post by nait
好好看看iconv的manpage,想想为什么函数原型是指向指针的指针
再比较下面两幅图中inbuf和outbuf有什么不同,你最后的free对不对
还有,c语言参数是传值的
如果所有你都搞清楚了就明白你为什么错了

请问，那个Emacs里面的那些栈窗口、Watch窗口是怎么做出来的？

nait

这就是传说中的gud
emacs自带的

pluskid

我的gud怎么就这样呢？
最多就是代码同步显示，没有什么Watch窗口之类的，那些窗口是怎么弄出来的呀？

nait

M-x gdb-many-windows RET

daniel_zhy

多谢, 简直是图文并茂.

明白了, 开始的确没领会iconv中的解释. 没注意inbuf, outbuf的指针也在跟着跑.

pluskid

Post by nait
M-x gdb-many-windows RET

奇怪，我没有这个命令呀，你是不是装了什么插件的？