程序代码：

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

bool str_in(char **);
void str_sort(char *[],int );
void swap( char **p1, char **p2);
void str_out(char *[],int);

const size_t BUFFER_LEN = 256;
const size_t NUM_P = 50;

int main(void)
{
    char *ps[NUM_P];
    int count = 0;
    
    printf("\nEnter successive lines, pressing Enter at the eng of"
               " each line.\nJust press enderto end.\n");
    
    for(count = 0; count<NUM_P ; count++)
    if(!str_in(&ps[count]))
      break;
    
    str_sort(ps,count);
    str_out(ps,count);
    return 0;
      
}

bool str_in(char **pString)
{
    char buffer[BUFFER_LEN];
    if(gets(buffer) == NULL)
    {
        printf("\nError reading string.\n");
        exit(1);
    }
    if(buffer[0] == '\0')
      return false;
      
    *pString = (char *)malloc(strlen(buffer) + 1);
    
    if(*pString == NULL)
    {
        printf("\nOut of memory.");
        exit(1);
    }  
    strcpy(*pString,buffer);
    return true;
}

void str_sort( char *p[],int n)
{

    bool sorted = false;
    while(!sorted)
    {
        sorted = true;
          for(int i=0 ; i<n-1 ; i++)
           if(strcmp(p[i],p[i+1]) > 0)
           {
               sorted = false;
               swap(&p[i],&p[i+1]);
           }
    }
}

void swap(char **p1,char **p2)
{
    char *pt = *p1;
    *p1 = *p2;
    *p2 = pt;
}

void str_out(char *p[], int n)
{
    printf("\nyour input sorted in order is:\n\n");
    for(int i=0 ; i<n ; i++)
    {
        printf("%s\n",p[i]);
        free(p[i]);
        p[i] = NULL;
    }
    return;
}