[C++知识库]C语言四种输入法加变式总汇，用函数指针表示

#include  <stdio.h>
#include  <stdlib.h>

void mp(int a[], int n)
{
	int  s ; 	
	for (int i = 0 ; i < n - 1 ; i++)	
	for (int j = 0 ; j < n -1 - i; j++)	
	if (a[j] > a[j+1])	
	s = a[j], a[j] = a[j+1], a[j+1] = s ;
}

void djh(int a[], int n)
{
	int  s ; 
	for (int i = 0 ; i < n - 1 ; i++)	
	for (int j = i + 1 ; j < n ; j++)	
	if (a[i] > a[j])	
	s = a[i], a[i] = a[j], a[j] = s ;
}

void sjh(int a[], int n)
{
    int s ;	
    for (int i = 0 ; i < n / 2 ; i++)	
    {		
 	    for (int j = i ; j < n - i ; j++)		
 	    {		
 	        if (a[i] > a[j])			
 	        s = a[i], a[i] = a[j], a[j] = s ;			
 	        if (a[n-1-i] < a[j])			
 	        s = a[n-1-i], a[n-1-i] = a[j], a[j] = s ; 		
 	    }	
 	}
}  

void dxz(int a[], int n) 
{
 	int  s ; 	
 	for (int i = 0 ; i < n - 1 ; i++)	
 	{		
 	    int  k = i ;		
 	    for (int j = i +1 ; j < n ; j++)		
 	    if (a[k] < a[j])		
 	    k = j ;		
 	    if (k != i)		
 	    s = a[k], a[k] = a[i], a[i] = s ;	
 	}
} 

void sxz(int a[], int n)
{
	int  s, k, m; 	
	for (int i = 0 ; i < n / 2 ; i++)	
	{		
	    s = i, k = i ;		
	    for (int j = i + 1 ; j < n - i ; j++)		
	    {			
	        if (a[s] > a[j])			
	        s = j ;			
	        if (a[k] < a[j])			
	        k = j ;		
	    }		
	    if (s == n-1-i && k == i)		
	    m = a[s], a[s] = a[k], a[k] = m ;		
	    else if (s == n-1-i)	
	    {			
	        if (s != i)			
	        m = a[s], a[s] = a[i], a[i] = m ;			
	        if (k != n-1-i)			
	        m = a[k], a[k] = a[n-1-i], a[n-1-i] = m ;		
	    }		
	    else		
	    {			
	        if (k != n-1-i)			
	        m = a[k], a[k] = a[n-1-i], a[n-1-i] = m ;			
	        if (s != i)			
	        m = a[s], a[s] = a[i], a[i] = m ;		
	    }			
	}
} 

void cr(int a[], int n)
{
	int  s ; 	
	for (int i = 1 ; i < n ; i++)	
	{		
	    int  j = i - 1 ;		
	    s = a[i] ;        
	    while (j >= 0 && a[j] > s)	    
	    {	    	
	        a[j+1] = a[j] ;	    	
	        j-- ;	    
	    }		
	    a[j+1] = s ;   		
	}
} 

void ps(int a[], int n, void (*p)(int a[], int n))
{
    (*p)(a, n) ;
} 

void main(void)
{
	int  n, x, q ;	
	printf("请输入数的个数n:\n") ; 	
	scanf("%d", &n) ; 	
	int  a[n] ;	
	printf("请输入%d个数:\n", n) ;	
	for (int i = 0 ; i < n ; i++)	
	scanf("%d", &a[i]) ;	
	printf("请选择排序方法, 输入序号:\n 1.冒泡\n 2.交换\n 3.选择\n 4.插入\n") ;	
	scanf("%d", &x) ;	
	if (x == 1)  ps(a, n, mp) ;	
	else if (x == 4)  ps(a, n, cr) ;	
	else if (x == 2 || x == 3)	
	{		
	    printf("请选择排序具体方法, 输入序号:\n 1.单向\n 2.双向\n") ;		
	    scanf("%d", &q) ;		
	    if (q == 1)  			
	    {			
	        if (x == 2) 	ps(a, n, djh) ;			
	        else             ps(a, n, sjh) ;		
	    }		
	    else if (q == 2)		
	    {			
	        if (x == 3)     ps(a, n, dxz) ;			
	        else              ps(a, n, sxz) ;		
	    }		
	    else  printf("输入无效\n") ; 
	}	
	else  printf("输入无效\n") ;	
	for (int i = 0 ; i < n ; i++)	
	printf("%d ", a[i]) ;
}