重新排列字符C ++ [英] Rearrange character C++

问题描述

我正在尝试用C ++编写一个程序，它接受用户输入的第一个字符并将其放到最后。程序是否可以执行此操作



例如。



用户输入：'stack'



'我应该旋转多少次？'



用户输入：2



输出：'ackst'



我尝试过：

I'm trying to write a program in C++ that takes the first character of users input and puts it to the end. Do program will do that for n tines

Eg.

User Input: 'stack'

'How many times should I rotate?'

User Input: 2

Output: 'ackst'

What I have tried:

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

int main()
{
	int K;

	string S;
	cout << "------------------------------------"<<endl;
	cout << "Enter a word: ";
	cin >> S;
	cout << "------------------------------------"<<endl;

	if(S.length() >1000)
	{
	cout << "------------------------------------"<<endl;
	cout << "Too many characters"<<endl;
	cout << "------------------------------------"<<endl;
	}
	
	if(S.length() ==1)
	{
	cout << "------------------------------------"<<endl;
	cout << "Not enough characters"<<endl;
	cout << "------------------------------------"<<endl;
	}
	
	if (S.length() <=1000 && 
  S.length() !=1)

        {
	cout << "Times of rotation: ";
	cin >> K
	}
}

推荐答案

试试这个：

Try this:

if (S.length() <= 1000 && S.length() != 1)
{
	cout << "Times of rotation: ";
	cin >> K;

	int L = S.length();

	for (int ii = 0; ii < K; ii++)
	{
		char chFirst = S[0];

		for(int i = 0; i < L - 1; i++)
			S[i] = S[i+1];

		S[L - 1] = chFirst;
	}
			

	cout << S;
}

一个简短的解释：

- 我们保存第一个角色

- 循环n次，其中n是旋转。

- 内循环：用第二个替换第一个字符，第二个用第三个替换，依此类推

- 将第一个字符设置为和字符串

A short explanation:
- we save the first character
- loop n- times, where n the rotation is.
- inner loop: replace the first char with the second, the second with the third and so on
- set the first character to the and of the string

在另一种方法中，您可以使用 string :: substr

In an alternative approach, you could use string::substr

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


void rotate (string & s, size_t r)
{
  r %= s.length();
  if ( r == 0) return;
  s = s.substr(r,s.length()-r) + s.substr(0,r);
}

void show_decorated(const string & message)
{
  cout << "------------------------------------\n";
  cout << message << '\n';
  cout << "------------------------------------\n";
}

int main ()
{
  int K;
  string S;
  cout << "------------------------------------\n";
  cout << "Enter a word: ";
  cin >> S;
  cout << "------------------------------------\n";

  if( S.length() > 1000)
  {
    show_decorated( "Too many characters" );
    return -1;
  }
  if(S.length() <= 1)
  {
    show_decorated("Not enough characters");
    return -1;
  }

  cout << "Times of rotation: ";
  cin >> K;
  rotate(S,K);
  show_decorated(S);
  cout << endl;

}

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