今天刘老师讲了const,类型转换,函数指针的用法,以前没能认识到函数指针的强大,刘老师写排序时用到了函数指针,暧昧感觉到了函数指针的强大;
最后他留了个作业,就是写string.h里的几个函数,我写了下,感觉写的很操蛋,效率不高,明天看看老师怎么写吧!
char* strcpy(char s1[],const char s2[]) { char *head=s1; while(*s1++=*s2++); return head; } char* strncpy(char s1[],const char s2[],size_t len) { char *head=s1; while((*s1++=*s2++)&&--len); *s1='\0'; return head; } char* strcat(char s1[],const char s2[]) { char *head=s1; while(*s1++); while(*s1++=*s2++); return head; } int strcmp(const char s1[],const char s2[]) { while(*s1&&*s2&&*s1==*s2)*s1++,*s2++; return *s1-*s2; } size_t strlen(const char s[]) { const char* head=s; while(*s)s++; return s-head; } void *memset(void *cell,int value,size_t size) { void*head=cell; char*p=(char*)cell; while(size--)*p++=value; return head; } void* memcpy(void* dest,const void* src,size_t size) { void* head=dest; char*p=(char*)dest; char*q=(char*)src; while(size--)*p++=*q++; return head; }