9.2

41
#include  <stdio.h>
#include  <string.h>
#include  <stdlib.h>
#include  <ctype.h>
char *fun(char  *s)
{ int  i, j, k, n;    char  *p, *t;
  n=strlen(s)+1;
  t=(char*)malloc(n*sizeof(char));
  p=(char*)malloc(n*sizeof(char));
  j=0; k=0;
  for(i=0; i<n; i++)
  {  if(isdigit(s[i])) {
/**********found**********/
       p[j]=s[i]; j++;}
     else
     {  t[k]=s[i]; k++; }
   }
/**********found**********/
   for(i=0; i<k; i++) p[j+i]= t[i];
   p[j+k]=0;
/**********found**********/
   return p;
}
void main()
{ char  s[80];
  printf("Please input: ");  scanf("%s",s);
  printf("\nThe result is: %s\n",fun(s));
}
42.
#include <stdio.h>
#include <string.h>

void fun( char  *a, char  *b, char  *c )
{
  int   i , j;     char   ch;
  i = 0;    j = strlen(b)-1;
/************found************/
  while ( i < j )
  {   ch = b[i]; b[i] = b[j]; b[j] = ch;
      i++;    j--;
  }
  while ( *a || *b ) {
/************found************/
     if ( *a )
       { *c = *a;  c++; a++; }
     if ( *b )
       { *c = *b;  c++; b++; }
  }
  *c = 0;
}

void main()
{
  char   s1[100],s2[100],t[200];
  printf("\nEnter s1 string : ");scanf("%s",s1);
  printf("\nEnter s2 string : ");scanf("%s",s2);
  fun( s1, s2, t );
  printf("\nThe result is : %s\n", t );
}
43.
#include <stdio.h>
#include <string.h>

void fun(char  *s, char  t[])
{
	int i,j=0;
	for(i=0;i<strlen(s);i++)
	{
		if(!((i%2)==0&&(s[i]%2)))
			t[j++]=s[i];
	}
	t[j]='\0';
}

void main()
{
  char   s[100], t[100];void NONO ();
  printf("\nPlease enter string S:"); scanf("%s", s);
  fun(s, t);
  printf("\nThe result is: %s\n", t);
  NONO();
}

void NONO ()
{/* 本函数用于打开文件，输入数据，调用函数，输出数据，关闭文件。 */
  char s[100], t[100] ;
  FILE *rf, *wf ;
  int i ;

  rf = fopen("in.dat","r") ;
  wf = fopen("out.dat","w") ;
  for(i = 0 ; i < 10 ; i++) {
    fscanf(rf, "%s", s) ;
    fun(s, t) ;
    fprintf(wf, "%s\n", t) ;
  }
  fclose(rf) ;
  fclose(wf) ;
}