#include<stdio.h>
#include<string.h>
main()
{
   int i=0,j=0,k=0;
   char a[100],b[100],c[100],*p;
  
   printf("please input string a:\n");
   scanf("%s",a);
   printf("please input string b:\n");
   scanf("%s",b);
  
   while(a[i]!='\0'&&b[j]!='\0')                      /********************************************
   {
      if(a[i]<b[j])
       {
         c[k]=a[i];
         i++;                          
       }
       else                                              先把那个较小的字符串放到c中
       {
         c[k]=b[j];
         j++;
       }
       k++;
    }                                                ***********************************************/
    c[k]='\0';                                       /*构成一个完整的字符串*/
    if(a[i]=='\0')                                   /*判断a中的字符串是否完全复制到c中*/
       p=b+j;                                        /*p指向数组b只未复制到c的位置*/
    else
       p=a+i;                                        /*p指向数组a中未复制到c的位置*/
    strcat(c,p);
    puts(c);

}