字符串倒置

[susuding]

[要求：编写函数，实现将“i am from hunan”倒置为“hunan from am i”;
想用指针数组实现，首先将指针数组指向字符串的首位置；
然后向后遍历字符串如果遇到空格，则将指针数组的下一个元素指向空格后的单词，并统计空格数；
最后根据统计的空格个数，将指针数组所存放的内容倒叙输出。
思路是否正确，具体该怎样实现呢，请指教？

[wei801516]

放入vector里面 用vector的反串机制 就哦了！~~安全

[zx0319]

读到一个空格断开，独立cpy到一个字符串中，之后逆序连接就好了。

[bdmh]

    char* p = "i am from hunan";
	int len = strlen(p);
	for (int i= len-1;i>=0;i--)
	{
		printf("%c",*(p+i));
	}

[justkk]

void revs(char *s)
{
    char *p1, *p2, c;

    if( s == NULL || *s == 0 ) return;

    p1 = s;
    p2 = s + strlen(s);

    while( --p2 > p1 )
    {
        c = *p1;
        *p1 = *p2;
        *p2 = c;
        p1++;
    }
}

[pstrunner]

3，4楼只是将整行进行倒置，没有把具体单词进行倒置。

应该还有一步，就是依据空格分隔单词，将每个单词倒置一下就可以啦；

具体算法与3，4楼雷同。

[pstrunner]

void invert_word(char *pstart, char *pend)
{
	int len = pend - pstart;
	for (int i=0; i<len/2; i++)
	{
		std::swap(*pstart, *(pend-1));
		pstart ++;
		pend --;
	}
}

void invert_string(char *pch)
{
	invert_word(pch, pch+strlen(pch));
	char *pre = pch, *post = NULL;
	while (NULL != (post = ::strchr(pre, ' ')))
	{
		invert_word(pre, post);
		pre = post + 1;
	}
}

int main(int argc, char **argv)
{
	char chStr[100] = "i am from hunan";
	invert_string(chStr);
}

[Quote=引用 5 楼 ptrunner 的回复:]

3，4楼只是将整行进行倒置，没有把具体单词进行倒置。

应该还有一步，就是依据空格分隔单词，将每个单词倒置一下就可以啦；

具体算法与3，4楼雷同。
[/Quote]

[xjz19901211]

string str = "i am from hunan";

	for (int i = 0; i < str.length()/2; i++)	//所有逆序
	{
		char temp = str[i];
		str[i] = str[str.length() - i - 1];
		str[str.length() - 1 - i] = temp;
	}

	for (int i = 0; i < str.length(); i++)
	{
		int j = i;
		while (str[j] != ' '&& str[j] != '\0') j++;//单词尾

		j -= 1;

		for (int k = i; k <= (j + i)/2; k++)	//单词再逆序
		{
			char temp = str[k];
			str[k] = str[j - (k - i)];
			str[j - (k - i)] = temp;
		}
		i = j + 1;//下一个单词
	}

差不多就这样吧……

[susuding]

感谢六楼和七楼，你们的方法都很对，但是纠结于指针数组的使用，能不能用指针数组的方法实现呢

[zhao1zhong6]

//来个更简单的
#include <iostream>
using namespace std;

int main(int argc, char* argv[])
{
	char p[]= "I am from shandong";
	for (int i =0,b = 1; i < strlen(p)/2; i++,b++)
	{
		char c = *(p+i);
		*(p+i) = *(p+ strlen(p)-b);
		*(p+ strlen(p)-b) = c;
	}
	cout<< p;
	system("pause");
	return 0;
}

[pstrunner]

typedef char *pchar;

void print_word(char *str)
{
	while (*str!=' ' && *str!='\0')
	{
		cout << *str;
		str++;
	}
}

void pointer_array(char *str)
{
	char *pos = str;
	pchar *pch = new pchar[strlen(str)];

	*pch = pos;
	pch++;
	while ('\0' != *pos)
	{
		if (' ' == *pos++)
		{
			*pch = pos;
			pch++;
		}
	}

	pch--;
	while (1)
	{
		print_word(*pch);
		cout << " ";
		if (*pch == str)
		{
			break;
		}
		pch--;
	}
	delete []pch;
}
int main(int argc, char **argv)
{
	char chStr[100] = "i am from hunan";
	pointer_array(chStr);
}

[Quote=引用 8 楼 susuding 的回复:]

感谢六楼和七楼，你们的方法都很对，但是纠结于指针数组的使用，能不能用指针数组的方法实现呢
[/Quote]

[pstrunner]

理解好题意再说：（

[Quote=引用 15 楼 fyzqzpd 的回复:]

C/C++ code
//来个更简单的
#include <iostream>
using namespace std;

int main(int argc, char* argv[])
{
char p[]= "I am from shandong";
for (int i =0,b = 1; i < strlen(p)/2; i++,b++)
{
……
[/Quote]

[rwjlqn]

只要有了思路 剩下的就是去实践了~

[xiaoboalex]

既然都用C++了，那就用STL吧，四行代码搞定：

#include <iostream>
#include <sstream>
#include <vector>
#include <iterator>
#include <algorithm>
using namespace std;

int main()
{
	vector<string> svec;
	copy(istream_iterator<string>(istringstream (string("i am from hunan"))), istream_iterator<string>(), back_inserter(svec));
	reverse(svec.begin(), svec.end());
	copy(svec.begin(), svec.end(), ostream_iterator<string>(cout, " "));

	system("pause");
}

[heguodong]

[Quote=引用 10 楼 xiaoboalex 的回复:]
既然都用C++了，那就用STL吧，四行代码搞定：

C/C++ code
#include <iostream>
#include <sstream>
#include <vector>
#include <iterator>
#include <algorithm>
using namespace std;

int main()
{
vector<string>……
[/Quote]
赞同,学C++的都多熟悉下STL吧

[acdbxzyw]

[Quote=引用 10 楼 xiaoboalex 的回复:]

既然都用C++了，那就用STL吧，四行代码搞定：

[/Quote]
杀鸡焉用牛刀？

#include<iostream>
#include <algorithm>
using namespace std;

int main(void)
{
char p[] = "let's go";
reverse(p,p+strlen(p));
return 0;
}

[lovelyzxg]

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <functional>

using namespace std;


void main()
{
const int VECTOR_SIZE = 8 ;

// Define a template class vector of strings
typedef vector<string > StrVector ;

//Define an iterator for template class vector of strings
typedef StrVector::iterator StrVectorIt ;

StrVector Tongue_Twister(VECTOR_SIZE) ;

StrVectorIt start, end, it ;

start = Tongue_Twister.begin() ; // location of first
// element of Tongue_Twister

end = Tongue_Twister.end() ; // one past the location last
// element of Tongue_Twister

//Initialize vector Tongue_Twister
Tongue_Twister[0] = "she" ;
Tongue_Twister[1] = "sells" ;
Tongue_Twister[2] = "sea" ;
Tongue_Twister[3] = "shells" ;
Tongue_Twister[4] = "by";
Tongue_Twister[5] = "the";
Tongue_Twister[6] = "sea" ;
Tongue_Twister[7] = "shore" ;

cout << "Before calling reverse \n" << endl ;

// print content of Tongue_Twister
cout << "Try this Tongue Twister: " ;
for(it = start; it != end; it++)
cout << *it << " " ;
cout << "\n\n" ;

// reverse the items in the vector Tongue_Twister
reverse(start, end) ;

cout << "After calling reverse \n" << endl ;

// print content of Tongue_Twister
cout << "Now try the reversed Tongue Twister: " ;
for(it = start; it != end; it++)
cout << *it << " " ;
cout << "\n\n" ;

}
csdn里面的程序~

[Zhhmily]

#include <iostream>
#include <stdio.h>
#include <string.h>

using namespace std;

int main()
{
	char str1[256] = "i am from hunan";
	char str2[256] = "";
	char *pDest = strrchr(str1, ' ');
	while (pDest)
	{
		sprintf(str2, "%s%s ",str2, pDest+1); *pDest = '\0';
		pDest = strrchr(str1, ' ');
	}
	sprintf(str2, "%s%s", str2, str1);
	printf("%s\n", str2);
}