keil环境下GUI.C(213):warningC275:expressionwithpossiblynoeffect这是是怎么回事?源码如下：voidcursorcov(unsignedchar**stylen,unsignedcharn){\x05unsignedchari,j;\x05stylecursorb=calloc(n,(32*(sizeof(unsignedchar))));\x05for(

Question

keil环境下GUI.C(213):warning C275:expression with possibly no effect 这是是怎么回事?
源码如下：
void cursorcov(unsigned char **stylen,unsigned char n)
{
\x05unsigned char i,j;
\x05stylecursorb=calloc(n,(32*(sizeof(unsigned char))));
\x05for(i=0;i

Answer 1

＝＝号不是＝号,没有任何赋值操作.
编译器按照你打的==告诉你,这个语句是多余的,有它和没它运行结果完全相同,有它是徒增计算量.