linux下C语言使用stdio.h库中popen和pclose函数编译报错

Question

error: implicit declaration of function ‘popen’; did you mean ‘fopen’? [-Werror=implicit-function-declaration]
error: implicit declaration of function ‘pclose’; did you mean ‘fclose’? [-Werror=implicit-function-declaration]
请问下为什么这样会报隐式声明错误呀？

源代码如下:

        GList *fList = s_wEntries;
        s_wEntries=NULL;
        FILE *fstream=NULL;
        char buff[1024];
        memset(buff,0,sizeof(buff));
        // execute command get all video
        char *launchword="find / -name *";
        strcat(launchword,cText);
        strcat(launchword,"*");
        if(NULL==(fstream=popen(launchword,"r")))
        {


        }
        else
        {
            memset(buff, 0x00, sizeof(buff));
            FileEntryInfo *Finfo;
            GtkMenuItem* searchmenuitem;
            while(NULL!=fgets(buff, sizeof(buff), fstream)){
                   if(buff[0]=='/')
                   {


                        searchmenuitem=gtk_menu_item_new_with_label(buff);
                        Finfo->uri=buff;
                        Finfo->pMenuItem=searchmenuitem;
                        g_list_prepend(s_wEntries,Finfo);   
                   }

                memset(buff, 0x00, sizeof(buff));
            }
            pclose(fstream);
        }

Answer 1

popen(), pclose(): _POSIX_C_SOURCE >= 2 || _XOPEN_SOURCE || _POSIX_SOURCE _BSD_SOURCE || _SVID_SOURCE

glibc是否支持这两个函数，需要测试上面的几个宏是否define了。如果这几个宏有任意一个define，则支持，否则就是不支持啦。