size_t strlen(const char *s)
{
size_t len = 0;
while(*s++)
len++;
return len;
}
char strcpy(char s1,const char *s2)
char *strcpy(char *s1,const char *s2)
{
char *tmp = s1;
while(*s1++ = *s2++)
;
return tmp;
}
char strncpy(char s1,const char *s2,size_t n);
char *strncpy(char *s1,const char *s2,size_t n)
{
char *tmp = s1;
while(n){
if(!(*s1++ = *s2++)) break; //遇到'\0'就结束循环
n--;
}
while(n--)
*s1++ = '\0'; //用'\0'填充剩余部分
return tmp;
}