strcpy函数的实现

/*my strcpy@author arhaiyun*/#include<assert.h>#include<string.h>char* m_strcpy(char* dst, char* src){//[1].Check to make sure it is validassert((dst != NULL) && (src != NULL));char* ret = dst;int length = strlen(src) + 1;//[2].Make sure memory is not repeatedif(dst <= src || dst >= (src + length)){//[3].Copy '\0' in the endwhile(length--){*dst++ = *src++;}}else{dst = dst + length - 1;src = src + length - 1;while(length--){*dst-- = *src--;}}//[4].return dstreturn ret;}