#include <iostream.h>
#include <stdio.h>

void replace (char str[20]); 

void main(void) 
{ 
char str[20]; 
printf("enter your string : "); 
gets(str); 
replace(str); 
 
cout<<endl<<str;
cin.ignore();

} 
//replace Function..........................

void replace (char str[20]) 
{ 
	//Compare all str[x] Items if ='a' then change it to '?' ......
	for(int x=0;x<20;x++)
		if(str[x]=='a')str[x]='?';

}