void char_type()
{
 char c=0xFF;
 if(c==-1)
  printf("signed");
 elseif(c==255)
  printf("unsigned");
 else
  printf("error!");
}

signed char c=*p; //c=-1
unsigned char c=*p;//c=255

 a[i] - '0' 

 #include <stdio.h> 
 #include <stdlib.h> 
 #include <string.h> 
  
 int main() 
 { 
  char str[10]; 
  int i, len; 
  
  while(scanf("%s", str) != EOF) 
  { 
   for(i = 0, len = strlen(str); i < len; i++) 
   { 
    printf("%d", str[i] - '0'); 
   } 
   printf("\n"); 
  } 
  
  return 0; 
 } 

 a[i] + '0' 

 #include <stdio.h> 
 #include <stdlib.h> 
 #include <string.h> 
  
 int main() 
 { 
  int number, i; 
  char str[10]; 
  
  while(scanf("%d", &number) != EOF) 
  { 
   memset(str, 0, sizeof(str)); 
   
   i = 0; 
   while(number) 
   { 
    str[i ++] = number % 10 + '0'; 
    number /= 10; 
   }   
   puts(str);  
  } 
  
  return 0; 
 }