ecs 32c

break linenumber

create breakpoint at specified line

break file:linenumber

create breakpoint at line in file

what does #include do?

reads the content of the header file

when do you declare variables?

before use

uninitialized variable assumes a…

default value

before we leave the os, you must always

free the memory from the heap

stack

special type of list where the last element in (push) is the first out (pop)

in a stack, you read and write from

the same end of the list

what does the following block of code do?

void push(int elem) { stack_buffer\[itop++\] = elem; }

\
adds element to top of stack

what does the following block of code do?

int pop(void) { if (itop > 0)

return stack_buffer\[--itop\];

el

return 0; }

remove element from top of stack

in a stack, if itop == 0, that means…

the stack is empty

when must functions be declared?

before use

arguments

local variables, values passed from caller

return value

single value returned to caller when function exits

void

signifies no return value/arguments

strings are stores as

character array

what does it mean for a string to be null-terminated?

last character in array is ‘\\0’ null (not explicitly in string literals)

what does #define msg “hello” do?

defines msg as “hello” throughout source fikle

datatype of an onject in memory determines…

the set of values it can have and what operations that can be performed on it

operators specify

how an object can be manipulated

expressions

a combination of values, variables, operators, and functions

variables

a named link/reference to a value stored in the system’s memory or an expression that can be evaluated

how does the unsigned version differ from its signed counterparts?

the unsigned version is roughly double the range of its signed counterparts

what is this operator? “==”

relational operator meaning “equal to”

what is this operator? “!=”

relational operator meaning “not equal to”

what is this operator? “&&”

logical operator for “and”

what is this operator? “||”

logical operator for “or”

logical operator for “!”

logical operator for “not”

the for loop has three expressions:

1. initialization
2. condition
3. increment

if any of the three expressions in a for loop are left empty,

the condition is assumed to be “true”

do-while loop

differs from the while loop - condition evaluated after each iteration. form:

do {

////

} while (condition);

what is the “break” keyword?

exits innermost loop or switch statement to exit early

variable scope

the region in which a variable is valid

variables declared outside of a function have (_) scope

global

what is the difference between the “while” loop, “do… while” loop, and “for” loop?

* while loop tests condition before execution of the block
* do… while loop tests condition after execution of the block
* for loop provides intialization, testing, and iteration together

goto

allows you to jump conditionally to arbitrary part of your code

putchar(c)

puts the character c on the standard output and returns the character printed or EOF on error

int getchar()

returns the next character from standard input and returns EOF on error

what does this do? a.out < file.txt

known as input redirection. treats file.txt as source of standard input.

in printf format specification, what is d and i?

integer

in printf format specification, what is x and X?

integer (hex)

in printf format specification, what is u?

unsigned integer

in printf format specification, what is c?

character

in printf format specification, what is s?

string

in printf format specification, what is f?

float

in printf format specification, what is d?

double

in printf format specification, what is e and E?

float(exp)

in printf format specification, what is %?

literal %

the end of the string is specified using

0

int sprintf(char string \[\], char format\[\], arg1, arg2)

format specification is the same as printf, and the output is written to string. returns the number of character written or negative value on error.

int sscanf(char str\[\], char format\[\], arg1, arg2)

the format specification is the same as scanf, and the input is read from str variable. returns the number of items read or negative value on error.

we can read data from text/binary files using

fopen()

fopen returns a (_) to the file stream if it exists or (_) otherwise

pointer; NULL

int fclose(FILE\*fp)

closes the stream. automatically called on all open files when program terminates

int getc(FILE\*fp)

reads a single character from the stream and returns the character read or EOF on error/end of file

char\[\] fgets(char line\[\], int maxlen, FILE\*fp)

reads a single line (upto maxlen characters) from the input stream (including linebreak). returns a pointer to the character array that stores the line (read-only). return NULL if end of stream

int putc(int c, FILE\*fp)

writes a single character c to the output stream, and returns the character written or EOF on error

int fputs(char line\[\], FILE\*fp)

writes a single line to the output stream, and returns 0 on success, EOF otherwise

int fscanf(FILE\*fp, char format\[\], arg1, arg2)

similar to scanf, sscanf, and reads items from intput stream fp

int main(int argc, char\*argv\[\])

argc is the count of arguments, and argv is the array of pointers to each of the arguments

pointer

memory address of a variable

address can be used to…

access/modify a variable from anywhere

strings are stored as…

null-terminated character arrays, where the last character == ‘\\0’

what are the string copy functions?

strcpy(), strncpy()

what are the string comparison functions?

strcmp(), strncmp()

what is the string length functions?

strlen()

what are the string concatenation functions?

strcat(), strncat()

what are the string search functions?

strchr(), strrchr()

The average and worst case big-O for quicksort are

* average: O(nlogn)
* worst case: O(n^2)

how to do quicksort?

* choose a pivot element
* move all the elements less than pivot to one side, all elements greater than pivot to other
* sorts sides individually (recursive algorithm)

average big-O for binary search

O(logn)

worst case Big-O for binary search:

logarithmic time

structure

a collection of related variables (of possible different types) grouped together under a single name

struct defines…

a new datatype

members of a struct

the variables declared within a structure

‘→’ operator

used to access members from structure pointers

how to declare arrays of int:

int x\[10\];

declaring arrays of structure

struct point p\[10\]

initializing arrays of int

int x\[4\] = {0, 20, 10, 2};

initializing arrays of structure

struct point p\[3\] = {0, 1, 10, 20, 30, 12};

struct point p\[3\] = {{0, 1}, {10, 20}, {30, 12}};

the size of a structure is…

greater than or equal to the sum of the sizes of its members

union

is a variable that may hold objects of different types/sizes in the same memory location

the size of the union variable is equal to

the size of its largest element

bit-field

a set of adjacent bits within a single ‘word’

malloc(size_t n)

allocates blocks of memory, and returns a pointer to unitialized block on success. returns NULL on failure

calloc(size_t size_n size)

allocates an array of n elements each of which is ‘size’ bytes. initializes memory to 0

free()

frees memory allocated to my malloc()

linked list

a dynamic data structure that consists of a sequence of records where each element contains a link to the next record in the sequence

* can be singly linked, doubly linked, or circular

binary tree

a dynamic data structure where each node has at most two children.

a binary search tree

a binary tree with ordering among its children

in a binary tree, usually, all elements in the left subtree are assumed to be (“less”/”more”) than the root element and all elements in the right subtree are assumed to be (“lesser”/”greater”) than the root element

“less”; ”greater”

pointer array

array of pointers

what is: int \*arr\[20\];?

an array of pointers to int’s

what is: char \*arr\[20\];?

an array of pointers to char’s

what is: char \*strs\[10\];?

an array of char arrays (or strings)

stack

a special type of list, where the last element in (push) is first out (pop)

in a stack, where do you read and write from the list?

the same end

store the stack as an…

a array buffer

True or False: Size of short integer and long integer would vary from one platform to another.

True. Depending on the os/compiler/system architechture you are working on, the range of data types can vary.

True or False: A long double can be used if range of a double is not enough to accommodate a real number.

True.