/*		C No Evil Homework
Each question carries equal weight.

The assignment must be turned in and committed to your SVN by August 31, 2011
at 11:00am. No late submissions will be allowed.

Instructions on how to use SVN and other information relating to
online submission can be found on the course website.

http://www.cs.illinois.edu/class/cs241/handin.html
*/

/*
Part I
Each of these examples can appear inside C programs.

The ... means additional (irrelevant) instructions.

For each example, answer the following questions:
(a) What does the code attempt to do?

(b) Correct the code listed
 */


/*Goal: Insert description of intended functionality here
 
*/
void Problem1(){
	int x;
	int *p = x;
}


/*Goal: Insert description of intended functionality here

*/
void Problem2(){
	float *p;
	*p = 12.5
}


/*Goal: Insert description of intended functionality here

*/
void Problem3(){
	float a;
	...
	if(0 < a < 1)
		printf("a is a value between 0 and 1.\n");
}

/*Goal: Insert description of intended functionality here

*/
void Problem4(){
	int x=5;
	int y;
	...
	if(x=y)
		printf("x and y are equal.\n");
	else
		printf("x and y are different.\n");
	
}

/*Goal: Insert description of intended functionality here

*/
void Problem5(){
	int x, *ip;
	float y, *fp;
	...
	ip = &x;
	fp = (float*)ip;
	y=*fp;
	
}

/*Goal: Insert description of intended functionality here

*/
void Problem6(){
	int a=0, b=10;
	while (a =! b){
		...
		a++;
	}
	
}

/*Goal: Insert description of intended functionality here

*/
void Problem7(){
	char s[30];
	scanf("%30s",s);
	s[30] = '\0';
}


/*Goal: Insert description of intended functionality here

*/
//Problem 8
void reset(int *x){
	x=0;
}

int main(){
	...
	int x=1;
	reset(&x);
	printf("x is now 0.\n");
	return 0;
}


/*Goal: Insert description of intended functionality here

*/
void Problem9(){
	char *s = (char *) malloc (50);
	...
	s="this is a string";
	free(s);
}

/*Goal: Insert description of intended functionality here

*/
void Problem10(){
	float *values;
	int i,n = 10;
	for(i=0;i<n;i++)
		values[i] = (float)i/n;
}

/*Goal: Insert description of intended functionality here

*/
void Problem11(){
	int **array;
	int i,j;
	array = malloc(10*sizeof(int *));
	for(i=0;i<10;i++)
		for(j=0;j<10;j++)
			array[i][j] = i*j;
}

/*Goal: Insert description of intended functionality here

*/
void Problem12(){
	char *str = (char *)malloc(10);
	int x;
	scanf("%9s",str);
	...
	switch(str) {
		case "blue":
			x=1; break;
		case "red":
			x=2; break;
		default: x=0;
	}
}

/*Goal: Insert description of intended functionality here

*/
void Problem13(){
	int i;
	...
	scanf("%d",&i);
	switch(i) {
		case 1: function1();
		case 2: function2();
		default: printf("Unknown command.\n");
	}
}


/*Goal: Insert description of intended functionality here

*/
void Problem14(){
	#define multiply(x,y)	x*y
	#define sum(x,y)	x+y
	int x = 3, y = 5;
	int z = 100 / multiply(x+1, y);
	z = 100 / sum(x*y, y);
	
}

/*Goal: Insert description of intended functionality here

*/
void Problem15(){
	int x;
	...
	if(x < 0){
		printf("invalid value.\n");
		exit;
	}
}

/*Goal: Insert description of intended functionality here

*/
void Problem16(){
	char str[4];
	strcat(str, "abcd");
}



/* Part II
Provide the code for the following functions.
You may use only the allowed operators specified in each problem.
You may not use any other operators, control constructs (if, do, while, ...),
or function calls.

You can only use constant values from 0L to 255L (0x0L to 0xFFL).

You may assume that your machine:
· Uses 2’s complement representation of integers
· Performs right shift arithmetically
· Uses either a 32- or a 64-bit representation of long integers
· Has unpredictable behavior when shifting a long integer by more
	than the word size

*/

long int clearBit(long int value, long int flag){
	/* returns value with all set bit positions from flag cleared
		using only the operators & ~ ^ | >> << ! + =
		
		For Example:  value=0xFF flag=0x55 -> retval=0xAA */

}


long int isEqual(long int x, long int y){
	/* returns 1L if x==y, 0L otherwise
		using only the operators & ~ ^ | >> << ! + = */

}