1) Figure out what the expression and/or statements evaluate to or print.
2) Short answer or fill-in the blank about C.


Note - they're a bit mixed up in this file ...


1a)
char c[10] = "jklmno";
for(int i=0; i<26; i++){
  c[i] += 2;
}
printf("%s\n", c);

answer:
* run-time error because c[25] is not okay.
* "lmnopq"...


2a)
What is the difference between a signed integer and unsigned integer?
Specifically, what is the difference between  
  int x; // range is -2^31 to 2^31 - 1
  unsigned int y; // range 0 to 2^32 - 1

answer: 


1b)
int i = 64;
i = i << 1; 128, 1000 0000b
i = i | 0x12;    0001 0010b -> 1001 0010
i = i >> 3; 1 0010b
printf("%i\n", i); 18

Answer:


2b)
What keyword identifies a loop that keeps track of a variable for you?
Answer: for
** Note - this question is both too vague and too easy.



1c) 
  int num = 123456;
  int i;
  for(i=0;i<3;i++)
    num1 = num1 + (1 << i);
    // 123456 + 1 = 123457 + 2 = 1234569 + 4 = 1234573
  printf("%d",num1);
  
  what is the value of num1?
  answer: 
 

2c) (True/False) A variable of an enumerated (enum) type only takes one value?
  Answer: True
** Note: question is vague and could be misunderstood.


1d)
int a = 0x00; 

a |= 0xab; 
a &= 0x0f; // 0x0000 000b
a = ~a;    // 0xffff fff4
a >> 2;    // 0x3fff fffd

printf("%d %x\n", a, a); 


2d)
What is struct used for?
Struct is used for collecting variables that are related to create a new type.
** Note - too vague, it is better to ask something specific where it is
easy to determine if you are correct or not.


1e) 
int main()
	int x=50;
	x = x % 3 + 5; // 2+5 = 7
	x = x>>1; // 3
	printf("%d\n", x);

Answer:


2e) How many bytes does a long double take in memory when using gcc on CS?
Answer:  (use sizeof) sizeof(long double)
  16


1f)

int i;
char c[10] = "abcdef";
              bbddff
for (i = 0; c[i]; i++)
  c[i] += c[i] & 0x1;  // c[0] += 1
                       // c[1] += 98 + 0x1
printf("%s\n", c);

Answer: 


1g) 
int i;
char c[100] = "HeLLoWoRLD";
for (i = 0; c[i]; i++)                  // if (c[i] & 32) "false"; else "true";
  printf("c[%d] '%c' -> %s\n", i, c[i], (c[i] & 32) ? "false":"true");
          c[0], 'H' -> true
	  c[1], 'e' -> false

97+_ & 32
0110 0001
65+_ & 32
0100 0001
0010 0000
Answer:



1h).
  char c = 'a'; // 97
  c += 4 + ('X'-'W'); //102
  c -= 2*2-1;//102-(4-1) = 98
  c -= ('a'-'A'); 98 - (97-65) = 66
  printf("%c\n", c); // B
  printf("%d\n", c); // 66
answer: 
        

2f.
  What happens when you use return in a function?
Answer: The function is terminated and the value is returned.
** Note - too easy?


1i)
int num = 70 % 8 * 2 + 4 % 3;
             4   * 2 + 4 % 3
	         8   + 4 % 3
		 8   +   1
		     9


2g)
What is the storage size and value range of an unsigned char on CS with gcc?
** Note - very nice, specific enough to easily tell if someone knows this or not based on their answer

1 byte, 0 to 255

1j)

int main(int argc, char *argv[]){
  char c = 'c'; // 99
  c += c>>2; 99 + 99/4 = 99 + 24 = 123
  for(int i=1; i<4;i++)
    c = ++c | i;
        124 | 1 = 125
	126 | 2 = 126
	127 | 3 = 127 // 0111 1111
	              //        11
  printf("%i\n", c); //prints 127
}



2h)
What does the variable argc contain?
Answer: the number of command lines arguments



1k)
#include<stdio.h>
#include<stdlib.h>

int main(int argc,char *argv[]){
  float number=10;

  for(int i=0; i<=number; i++){
    printf("%.0lf x %d = %.0lf\n", number, i, i*number);
             10 x 0 = 0
	     10 x 1 = 10
	     ...
	     10 x 10 = 100
  }
  printf("------------------\n");
  for (int k=1; k<=number; k++){
    printf("%.0lf / %d = %.2lf\n", number, k, number/k);
             10 / 1 = 10.00
	     10 / 2 = 5.00
	     10 / 3 = 3.33
	     10 / 4 = 2.50
	     ...
  }
  return 0;
}


2i)
What is a SWITCH statement in C?
Answer:
** Note -- too vague