C Learners

salahuddin_66 · 08-29-2004, 10:36 PM

i am just trying to learn C my self

i compile in gcc
-----------------------------
gcc -ansi 87b.c -o test
----------------------------

but i could not understand this prog the use of
-------------
right = 0;
------------
right = 1;
-------------
if(!right)
------------
for(chances=0; chances<3 && !right; chances++) "only the not right use why"

Code:

 
#include <stdio.h>

int main(void) 
{
int answer, count , chances, right;

for (count=1; count<11; count++){
    printf("What is %d + %d?", count, count);
    scanf("%d" , &answer);
    
    if (answer == count+count) printf("Right!\n");
    else{
       printf("Sorry, you're wrong\n");
       printf("Try again\n");
       
       right = 0;
       
       /* nested for */
       
           for(chances=0; chances<3 && !right; chances++){
	   printf("What is %d + %d?", count, count);
           scanf("%d" , &answer);
	   
	   if (answer == count+count){
	   printf("Right!\n");
	   right = 1;
	   }
	   
	  }
	  
	  /*if answer still wrong, tell user */
	  
	  if(!right)
	   printf("What is %d + %d?", count, count);
	  }
	  }
	  
	
return 0;

}

masand · 08-29-2004, 10:48 PM

hi
the program is quite clear

right=0 ,right =1 are used as flags here, these can be used when we want to mark a state

here when u go to else part then , mark it as right=0,which means we have gone to that part,else right would not have been =0

so later
for
if(!right)
if we have right =0
then !right make it '1'and the if condition bcomes

if(1)
which is true and it goes on to that section of IF condition

if it was

if(0)
then it wuld have not gone there

did u get this???

regards

salahuddin_66 · 08-29-2004, 11:09 PM

thanx understand

now tell me just

if(1)

will go to the if statement that contains the right =1 (the second if)

and the other if (0) will go the frist ( if or else) section ???

masand · 08-30-2004, 02:30 AM

hi
no. no u got this wrong
for ex.
we have x=1;
then if we have this statement
if(x==1)
will check whether x is equal to 1

so if(1) means that the if statement is true always and it will execute the block of the if statenment

1 = true
and 0 = false
in boolean

so if u use if(1) in a c program then the block below it will b executed all the time

so in ur program if right is set to 0 then
then the block of
if(!right) will be executed
i.e "printf("What is %d + %d?", count, count);"
also if(!right ) is same as (if right==0)
when u use some kinds of flags we geneally use this
i hope now u get it

regards

salahuddin_66 · 08-30-2004, 03:35 AM

yes

thanx