如何改善这种算法? (三串反转) [英] How would you improve this algorithm? (c string reversal)
问题描述
工作通过一些我在网上找到节目访谈的挑战,我不得不写一个算法来扭转一个const char *,并返回一个指针到一个新的char *。我想我有它,而是让它正常工作,我不得不做一些靠不住的东西 - 基本上不必考虑空终止字符自己。不知怎的,我觉得这是不对的,但我很为难,我想知道,如果有人可以帮助我:
的char *反向(为const char *海峡)
{
INT长度= strlen的(STR);
字符* reversed_string =新的char [长度+ 1];
的for(int i = 0; I<长度; ++ I)
{
reversed_string [i] = STR [(长度1) - 我]。
}
//需要空终止字符串
reversed_string [长度] ='\ 0';
返回reversed_string;
}
INT主(INT ARGC,字符* argv的[])
{
字符* rev_str =反向(测试);
COUT<< 你的字符串逆转是这样的:<< rev_str<< ENDL;
删除rev_str;
rev_str = 0;
返回0;
}
STD ::扭转
从<算法>
适用于字符串和字符
数组:
字符串str =你好;
焦炭CHX [] =你好;
反向(str.begin(),str.end());
反向(CHX,CHX +的strlen(CHX));
COUT<<海峡<< ENDL;
COUT<< CHX<< ENDL;
/编辑:这当然,修改原始字符串。但STL救援。下面创建一个新的逆转字符串。 (?)不幸的是,这并不直接对C时不创建工作字符
阵列附加(隐含)复制:
字符串reverse_string(字符串常量和放大器;旧){
返回的字符串(old.rbegin(),old.rend());
}
COUT<< reverse_string(你好)<< ENDL;
Working through some programming interview challenges I found online, I had to write an algorithm to reverse a const char * and return a pointer to a new char *. I think I have it, but to make it work properly I had to do some wonky stuff - basically having to account for the null-terminating character myself. Somehow I feel this is wrong, but I'm stumped, and I was wondering if someone could help me out:
char * reverse(const char * str)
{
int length = strlen(str);
char * reversed_string = new char[length+1];
for(int i = 0; i < length; ++i)
{
reversed_string[i] = str[(length-1) - i];
}
//need to null terminate the string
reversed_string[length] = '\0';
return reversed_string;
}
int main(int argc, char * argv[])
{
char * rev_str = reverse("Testing");
cout << "Your string reversed is this: " << rev_str << endl;
delete rev_str;
rev_str = 0;
return 0;
}
std::reverse
from <algorithm>
works for strings and char
arrays:
string str = "Hello";
char chx[] = "Hello";
reverse(str.begin(), str.end());
reverse(chx, chx + strlen(chx));
cout << str << endl;
cout << chx << endl;
/EDIT: This, of course, modifies the original string. But STL to the rescue. The following creates a new reversed string. Unfortunately (?), this doesn't work directly on C char
arrays without creating an additional (implicit) copy:
string reverse_string(string const& old) {
return string(old.rbegin(), old.rend());
}
cout << reverse_string("Hello") << endl;
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