给出一个函数来输出一个字符串的所有排列

#include "stdio.h"
#include "stdlib.h"
#include "string.h"
   
void permutation(char * p_str, char * p_begin)
{
    if(!p_str || !p_begin)
    {
        return;
    }
 
 
    if('\0' == *p_begin)
    {
        printf("%s\n", p_str);
    }
    
    else
    {
        char * p_ch;
  
        for(p_ch = p_begin; *p_ch != '\0'; ++p_ch)
        {
            char temp;
   
            
            
				temp = *p_ch;
                *p_ch = *p_begin;
                *p_begin = temp;
           
			
            permutation(p_str, p_begin + 1);
   // a b c d
   // 
            
			//(*p_ch != *p_begin)
            
				temp = *p_ch;
                *p_ch = *p_begin;
                *p_begin = temp;
			
        }
    }
}

int main(int argc, char * argv[])
{
    
    
    char strr[6]="123";
	// 1 3 3
	// 
    //char strd[4];
    permutation(strr, strr);
    return 0;
}