Increase in pointer capability
Hi all, I found the following function, which is used to remove the head of a linked list. void RemoveHead(node **head) { node *temp; if (head && *head) { /* Corrected code */ temp = (*head)->next; free(*head); *head = temp; } } 1. Why is the purpose of 'head' in the 'if' condition? Shouldn't '*head' suffice? 2. This function has an argument, which is a po...
by bsd_lite - C/C++ - 2008-10-17 21:58:56 阅读（1459） 回复（4）
A.7.1 pointer Generation If the type of an expression or subexpression is ``array of T,'' for some type T, then the value of the expression is a pointer to the first object in the array, and the type of the expression is altered to ``pointer to T.'' This conversion does not take place if the expression is in the operand of the unary & operator, or of ++, --, sizeof, or as the left operand of an as...
我想增加一个文件系统的大小 ！ (/dev/data ) 原大小: # df -k Filesystem 1024-blocks Free %Used Iused %Iused Mounted on /dev/hd4 65536 55948 15% 1008 4% / /dev/hd2 458752 20380 96% 14990 14% /usr /dev/hd9var 65536 59212 10% 383 3% /var /dev/hd3 65536 63364 4% 40 1% /tmp /dev/hd1 65...
table表中某列flag，定义为number（1，0），现将其改为number（2，0）。 我在SQL explorer中修改，commit，apply以后，试着将其中flag列某个数值由9改成11却不成功，提示错误号为12289，capability not supported。 这是什么原因？还需要修改另外的表参数吗？初来乍到，还望不吝指教！ 谢谢！
Thou shalt not follow the NULL pointer, for chaos and madness await thee at its end. Clearly the holy scriptures were mis-transcribed here, as the words should have been ``null pointer'', to minimize confusion between the concept of null pointers and the macro NULL (of which more anon). Otherwise, the meaning is plain. A null pointer points to regions filled with dragons, demons, core dumps, and...
struct P{ string a; string b; }; struct G{ P ab; G *pt[4]; G(){//initialize new tree node ab.a=" "; ab.b=" "; for(int i=0;i<4;i++) pt=NULL; } }; G g; function(g); 我有以上一些code, 当我在function()里面访问g->pt时就会出错。 在unix下编译时的出错信息是: Error: pointer type needed instead of G. 不懂:cry:怎么回事, 谁能帮帮我~谢谢各位大虾~
dereferencing pointer to incomplete type dereferencing pointer to incomplete type 的错误也是未包含某些头文件造成的! 分析数据包：判断通信双方的操作系统、网络信息流量、通过路由的数据包大小、数据包内容。 以太网：以太网的桢？ 以太网中，数据是以被称为帧的数据结构本为单位进行交换的。 现在最常用的帧格式MAC V2 v2帧的格式： （插入8字节）目的地址（6字节）-源地址（6字节）-类型（2字节）-数据（46-150...
试了一下reference及pointer的用法 ------------------------ int main() { int val=1024; int *&ref = &val } 如此无法通过编译 ------------------------ 于是我改成下面两种即可编译 1. ------------------------- int main() { int val=1024; int *pr = &val int *&ref = pr; } ------------------------- 2. ------------------------- int main() { int val=1024; int *const &ref ...
我写的print(head)函数里 void print(head)//head 是一个全局变量，是指向链表头的指针 { struct stitch *p; unsigned long sti_count1=0; p=head; .... } 'p=head;'这条语句系统提示"Nonportable pointer coversion" 这是什么原因呀，大家帮帮忙，
