Lecture 2

Question 1

basic function syntax

Answer 1

return_type function_name (argument list) {
//body of function
return statement;
}
ex) int add (int a, int b) {
return a + b;
}

Question 2

basic function with no return syntax

Answer 2

void function_name (argument list) {
//body of function
}
*no return statement because return_type is void

Question 3

function prototype syntax

Answer 3

return_type function_name (arg list);
ex) int add(int a, int b);

Question 4

what is a function prototype?

Answer 4

definition of the function without initializing it

Question 5

can you call a function prototype in main( ) and then initialize it after main( )?

Answer 5

yes, you can
the function prototype defines the function (no implementation yet) but the system recognizes it from the prototype
after running through main( ), the system is able to execute the function call since the implementation happens after main( )

Question 6

can you call a function in main( ) and then define/implement it after main()?

Answer 6

no, the system will stop at the function call because it wont recognize the function call (not defined before called) and wont know what to do for it (not implemented before or after call)

Question 7

what is the most basic linear data structure in c?

Answer 7

c structures (aka structs)

Question 8

struct basic syntax

Answer 8

struct name {
field 1;
field 2;
field 3;
};
ex) struct student {
unsigned int pid;
char name[50];
}

Question 9

can you initialize the fields when you define the struct?

Answer 9

NO, cannot initialize fields within the definition of the struct (syntax)

Question 10

how do you assign values to the fields of your struct?

Answer 10

using the “.” operator (dot)
ex) student.pid = 12;
*the dot operator goes to that field in memory and assigns the int pid to 12

Question 11

can you use the dot operator for strings/chars?

Answer 11

NOOO

Question 12

how do you assign values to string/char fields of your struct?

Answer 12

strcpy( struct.field, “string”);
string function, copies the string then puts into the character array at the allocated indexes for that field

Question 13

what is the stack frame’s lifetime?

Answer 13

1) created when the function is called
- stores variables local to that
function in the stack frame
- push functions onto stack
2) destroyed when the function returns
- all local variables go out of scope
- pop functions off of the stack

Question 14

what are the stack’s operations to add/remove functions in the stack?

Answer 14

push –> pushes functions onto the stack when called
pop –> “pops” functions off the stack after they return

Question 15

what sequence does the stack adhere to?

Answer 15

LIFO (last in first out)

Question 16

do push and pop remove the functions/variables from memory?

Answer 16

no, they only update the memory register
**not creating or destroying memory just changing the value stored there

Question 17

if you have a function pushed on the stack and the local variables aren’t initialized, are they equal to 0?

Answer 17

no, whatever is left in memory at those addresses in the stack will be assigned to those variables
- leftover from what was on the stack from before
**important to initialize upon creation

Question 18

if you have a function popped off the stack and the local variables aren’t initialized, are they set to 0?

Answer 18

no, there is nothing initializing the memory back to zero
**important to initialize upon creation

Question 19

where is the stack located?

Answer 19

in main memory (RAM)

Question 20

what is the stack frame created for?

Answer 20

each function call has it’s own stack frame where the variables local to that function are stored while its pushed onto the stack until it gets popped off the stack

Question 21

int foo(int a, int b) {
return a + bar(a + b);
}
int bar (int z, int w) {
int x = z + w;
z = square(z);
return x + z;
}
int square (int x) {
return x * x;
}
how many stack frames are created?

Answer 21

3 for each function called
(foo, foo calls bar, bar calls square)

Question 22

what kind of function is puts( )?

Answer 22

puts is an output function included in stdio.h extension

Question 23

what does puts( ) do?

Answer 23

function that only takes character array/strings that is formatted by coder, then prints it to the console
*similar to printf but only accepts chars
- writes one character @ a time

Question 24

what kind of function is gets()?

Answer 24

gets is an input function included in stdio.h extension

Question 25

what does gets() do?

Answer 25

• waits for the coder/user to hit the input something into the terminal and hit the return key
• takes the characters you put in and puts them into the character array
• reads input (stdin) one character @ a time

Question 26

how do puts and gets differ from printf and scanf?

Answer 26

• puts and gets only accept characters/strings
• printf and scanf can convert to integers etc

Question 27

what if the user entered 10 when prompted by gets() and printed by puts()?

Answer 27

accepted as the string ‘10’ not the integer, prints ‘10’ as string not integer

Question 28

what should you do if you want convert a string to an integer?

Answer 28

atoi()
changes ASCII (characters) to integers
“a to i”

Question 29

what is a different way to create a struct?

Answer 29

using typedef

Question 30

what is typedef?

Answer 30

definition type, allows us to create own datatypes without using struct

Question 31

what is the implementation of typedef?

Answer 31

typedef struct {
//fields
} name;

Question 32

if you use struct only, how do you initialize that data type?

Answer 32

struct name_of_datatype variable_name;

Question 33

if you use typedef, how do you initialize that data type?

Answer 33

name_of_datatype variable_name;
**don’t have to say struct if you use typedef