C-WS4-ArraysAndPointers

Question 1

K1 Word

Answer 1

ANSI Standard size of type int (4 bytes)

unit of data that can be addressed and moved between storage and computer processer

Question 2

K2 Environment Variables

Answer 2

define the characteristics of a specific environment

can be inherited from system definitions, yet modified at an application level without affecting the environment of other applications or the system settings

Question 3

K3 Main arguments(argc, argv, envp)

Answer 3

int argc (number of command line arguments argv[] holds for this current program’s execution)

char ** arg (aka, char * argv[], pointer to the list of actual const string arguments)

char ** envp (char * envp[], holds environment variables as string constants, plus the header: PATH=)

argc: instructions to command line,

argv: pointer to arguments given to main

envp: holds env variables as string constants, please header PATH=

Question 4

K4 Array

Answer 4

stores fixed-size sequential collection of elements of the same type

Question 5

K5 sizeof

Answer 5

computes the size of it operand.
printf(“%lu\n”, sizeof(char)); //1
printf(“%lu\n”, sizeof(int)); //4
printf(“%lu\n”, sizeof(float)); //4
printf(“%lu”, sizeof(double)); //8

Question 6

Q1 What is a word? what does it represent?

Answer 6

represents the standard size of type int (4 bytes),

unit of data that can be addressed and moved between storage and computer processer

Question 7

Q2 given the following piece of code, answer the questions below:

Answer 7

a) sizeof(str): == 8, strlen(str)==7, the string itself is 7 characters long, but its size includes the escape character \0
b) sizeof(arr) == 40, sizeof(a)==8, the size of the array is 10 elements of size it (4 bytes), therefore 4*10=40, array decays to a pointer when passed as a variable. on 64-bit system, that’s 8 bytes. or 4 bytes on 32 bit system

Question 8

Q3 which lines of code below are possible? which are not? why?

Answer 8

char* p = “lalala”;
char arr[10] = “lalala”;

\++p;
/*++arr; arr is not a character pointer. won't compile.*/
/*  *p = 's'; *//*causes a segmentation fault*/
/*p[0] = 's';*//*causes segmentation fault*/
arr[1] = 's';
*(arr + 1) = 's';
1[arr] = 's';

p allocation: x616x616c sizeof: 8, multidimensional vs **
arr allocation: x616x616c sizeof: 10, multidimensional