CS 202 f2017 quiz 3.  cs202xy login: _____________________________________________

Note: answers put in // line afterwards, and sometimes some notes in the problems about why/how

Note: for each, you should copy/paste the original

1. For each, give the value printed.

1a)
char c = 97;
printf("%c", c);
// a

1b)
char c = 97;
printf("%i", c);
// 97

1c)
char c = 127;
printf("%i", c << 1);
// 127*2 = 254

1d)
char c = 127;
printf("%i", c & 15);
// 1111 1111b & 1111b = 1111b = 15

1e)
int x = (1 < 2) && (2 < 1);
           1    &&    0
	         0
printf("%i", ++x);
// 1


1f)
int x = (1 < 2) | (2 < 1);
           1    |    0
	        1
printf("%i", x++);
// 1 is printed, final value of x is 2

1g)
int x = 1;
switch (x) {
  case 1: x++;
  case 2: x++;
  case 3: x++;
  default: x++;
}
printf("%i", x);
// case 1 happens, then the rest do as well because there is no break
// final value of x is 5

1h)
for(int i=0; i < 5; i++)
  ;
printf("%i", i);
// final value of i is 5 - the value causing the "i < 5" condition to be false


1i)
int x=0;
while((x=1) > 2) // x is set to 1 and condition is false
  x++;
printf("%i", x); // 1

1j)
char c = 127;
c++; // -127 because of overflow
printf("%i", c);



2) Give the min, max, and # bytes for each of the following data types on CS with gcc

*** NOTE *** in these problems I am using ^ to mean exponent.

2a) unsigned char
0 to 255, 1 byte

2b) char
-128 to 127, 1 byte

2c) int
-2^31 to 2^31-1, 4 bytes
roughly -2 billion to 2 billion

2d) unsigned int
0 to 2^32-1, 4 bytes
roughly 0 to 4 billion

2e) short
-2^15 to 2^15-1, 2 bytes
roughly -32000 to 32000

2f) unsigned short
0 to 2^16-1, 2 bytes
roughly 0 to 65000

2g) long int
-2^63 to 2^63-1, 8 bytes
roughly 8*10^18 to 8*10^18

2h) unsigned long int
0 to 2^64-1, 8 bytes
roughly 0 to 16*10^18

2i) float - max/min, precision (# digits)
roughly -10^127 to 10^127, roughly 7 digits of precision, exponent goes between -126 and 127.
4 bytes

2j) double
roughly -10^1023 to 10^1023, roughly 15 digits of precision, exponent goes between -1022 and 1023
8 bytes

2k) long double
roughly -10^16000 to 10^16000, roughly 34 digits of precision, exponent goes between roughly -16000 and 16000
16 bytes


3) Give an extremely short phrase (at most 10 words) describing what each keyword does

3a) static, for local variable - global storage, local scope

3b) static, for global variable - cannot be used in separate .c files

3c) const - variable value cannot be changed after initialized

3d) while - loop while condition is true

3e) #define - set a pre-processor "variable" (called a "macro")
e.g.,
#define TRUE 1

3f) sizeof - # of bytes in a variable or data type

3g) extern, for global variable - variable is declared in another .c file

3h) enum - integer type with named values
e.g.,
typedef enum FRUIT_T {apple, banana, orange} fruit_t;

3i) typedef - make a shorcut for a data type (often used with struct, enum)

3j) union - type that allows one variable that could take multiple types
e.g.,
typedef struct GRADE_T {
  char type; // 'i' for int, 'f' for float, 'l' for letter
  union grade {
    int i;
    float f;
    char l;
  };
} grade_t;
grade_t g; g.type = 'f'; g.grade.f = 97.23;

3k) struct - data type for grouping variables together into a single variable

3l) for - loop while condition is true, includes initializer / condition / body / increment.

3m) switch - run different statements depending on value of integer expression

3n) break - stop innermost loop the break is in, skip to end of loop

3o) continue - go to top of innermost loop continue is in, and check the loop condition

3p) default - for switch statement, statements that run if expression doesn't match any case statements