W21 LAB 4代做、代写C++程序、代做c/c++编程

日期：2021-02-24 11:27

W21 LAB 4

Local and Global variables. “Pass by value”

,

string and other library functions. 2D arrays.

Pointer basics.

Due: Feb 24 (Wednesday) 11:59 pm Total marks: 120 pts

Problem A0 Scope, Life time and Initialization of global

variables, local variables and static global/local variables

Download the files lab4A0.c and cal.c. Read the code first. Observe that for functions

that have no parameters, they are declared as functionName(void), e.g., modify (void).

It will also work if we declare them as functionNAme(), but the former is the preferred way of

declaring such functions.

Compile (how?) and run the main program.

[Scope and initialization of global variables] Observe that global variables x and y, which are

defined in cal.c, can be accessed in other file lab4A0.c (x and y have global scope), and in

order to access x and y, the other file needs to declare them using keyword extern.

Moreover, the output x:0 y:0 implies that global variables x and y, which were not

initialized explicitly, all got initialized to 0 by the complier. Also observe how the function

modify(), which was defined in cal.c, was declared and used in the other file. In declaring

a function, keyword extern is optional.

Also observe how the values of x and y are changed in function modify() using compound

operators, and how the second operation is evaluated following the operator precedence, giving

y a new value 120, not 100 or 102.

[Scope of local variables] Next, uncomment the commented printf statement, and compile

the files again. Observe the error message. The problem here is that local variable a’s scope is

the block/function in which it is defined. Here a is defined in the if block, so it is not accessible

outside the if block, even in the main function. Modify by declaring a before the if clause, i.e.,

change to int a; if (y != 0){ a = y;} Now a’s defining block is the main function, so

a’s scope is anywhere in main after its declaration, which makes it accessible after the if block.

Compile and run the program again.

[Lifetime of local variables] Uncomment the commented block near the end of main. Observe

that function aFun is called several times, and all produce the same value for counter. This is

because local variable counter in the function has life time ‘automatic’ – comes to life

(allocated in memory) when function aFun is called and vanishes (deallocated from memory)

when function aFun returns. So each time the function is call, a brand-new variable called

counter is created and initialized. Thus it always has value 100.

[Initialization of local variables] Observe the initial values of local variable b in aFun. In C and

Java, if a local variable is not explicitly initialized, it is not initialized to 0 (or, more precisely, it is

initialized with some garbage values). Run the program again and you might see different values.

2

[Lifetime of static local variables] Next, make counter a static local variable, compile and run

again. Observe that the value of counter is different in each call and its value is maintained

between the function calls, due to the fact that in C a static local variable has persistent lifetime

over function calls, similar to global variable. (Note that, a static local variable’s scope is still

within the block where it is defined. So counter is still not accessible outside the function. Try

to access counter in main and you will get compiling error.) Also observe that compound

operator += is used.

[Initialization of static local variables] Next, remove the initial value 100 for counter, compile

and run again, and observe that in the first time call counter gets an initial value 0. As

discussed in class, global variables and static local variables get initial value 0 if not initialized

explicitly. (‘Regular’ non-static local variables such as b, as we observed above, are not initialized

to 0, or, more precisely, are initialized with some garbage values).

[Scope of static global variables] Finally, make y in cal.c to be static and compile again.

Observe that global variable y becomes inaccessible in main. (But it is still accessible later in file

cal.c where it is defined.)

No submission for this question. lab3D0.c

Problem A1 variable scope, “Pass-by-value”, tracing a program

with debugger (5pts)

Specification

In order to understand variable scope and pass-by-value in C, in this exercise we trace a program

using a software tool called debugger, rather than using print statements. A debugger allows us

to examine the values of variables during program execution. With a debugger, you can do this

by setting several “breakpoints” in the program. The program will pause execution at the

breakpoints and you can then view the current values of the variables.

You will use a GNU debugger call gdb. It is a command-line based debugger but also comes with

a simple text-based gui (tui).

To debug a C program using gdb, you need to compile the program with –g flag of gcc.

Implementation

Note: for this exercise you may want to connect to lab environment, as you may not have the

same debugger on your system.

Download the program swap.c, and compile using gcc –g swap.c. Then invoke gdb by

issuing gdb –tui a.out. And then press enter key.

A window with two panels will appear. The upper panel displays the source code and the lower

panel allows you to enter commands. Maximize the terminal and use arrow keys to scroll the

upper panel so you can see the whole source code.

First, we want to examine the values of variables mainA and mainB after initialization. So we

set a breakpoint at the beginning of line 11 (before line 11 is executed) by issuing break 11.

Observe that a “b+” or ”B+” symbol appears on the left of line 11. We want to trace the values

of variables x and y defined in function swap, both before and after swapping, so we set

breakpoints at (the beginning of) line 18 and line 21. Finally we set a breakpoint at line 12 so

that we can trace the value of mainA and mainB after the function call.

When the program pauses at a breakpoint, you can view the current values of variables with the

print or display or even printf command.

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Sample input/output

red 64 % gcc –g swap.c

red 65 % gdb –tui a.out

….

Reading symbols from a.out...done.

(gdb) break 11

Breakpoint 1 at 0x400488: file swap.c, line 11.

(gdb) break 18

Breakpoint 2 at 0x4004a3: file swap.c, line 17.

(gdb) break 21

Breakpoint 3 at 0x4004b5: file swap.c, line 21.

(gdb) break 12

Breakpoint 4 at 0x400497: file swap.c, line 12.

(gdb) run

Starting program: /eecs/home/huiwang/a.out

Breakpoint 1, main () at swap.c:11

(gdb) display mainA

mainA = ?

(gdb) display mainB

mainB = ?

(gdb) continue

Continuing.

Breakpoint 2, swap (x=1, y=20000) at swap.c:18

(gdb) display x

x = ?

(gdb) display y

y = ?

(gdb) display mainA

……?

(gdb) display mainB

……?

(gdb) continue

Continuing.

Breakpoint 3, swap (x=20000, y=1) at swap.c:21

(gdb) display x

x = ?

(gdb) display y

y = ?

(gdb) continue

Continuing.

Breakpoint 4, main () at swap.c:12

(gdb) display mainA

mainA = ?

(gdb) display mainB

mainB = ?

(gdb) display x

……?

(gdb) display y

……?

(gdb) quit

What do you get for

mainA and mainB?

/* continue execution to the

next breakpoint. Notice the

position of > sign */

What do you get for x

and y? Are they

swapped?

What do you get

for x and y?

What do you get for mainA

and mainB? Are they

swapped?

What do you get for mainA and

mainB? Are they swapped?

What do you get here, and

why?

/* run the program until the

first breakpoint. Notice the >

sign on the left of the upper

panel */

What do you get

for mainA and

mainB, and why?

4

Submission Write your answers into a text file, and submit it. Or submit a snapshot of your

gdb session. (Anything that show your work is acceptable.)

submit 2031ON lab4 text_file_or_pictures

or, use websubmit at https://webapp.eecs.yorku.ca/submit/

Problem A2 Variables (10 pts)

Specification

Complete the ANSI-C program runningAveLocal.c, which should read integers from the

standard input, and computes the running (current) average of the input integers. The program

terminates when -1 is entered.

Implementation

• Define a function void r_avg(int sum, int count)which, given the current sum

sum and the total number of input count, computes and displays the running average in

double. The current sum and input count are maintained in main.

• Complete main so that input is read and maintained. Don’t add printf statement in main.

Sample Inputs/Outputs:

red 307 % gcc –Wall runningAveLocal.c

red 308 % a.out

Enter number (-1 to quit): 10

running average is 10 / 1 = 10.000 Floor is 10 Ceiling is 10

Enter number (-1 to quit): 20

running average is 30 / 2 = 15.000 Floor is 15 Ceiling is 15

Enter number (-1 to quit): 33

running average is 63 / 3 = 21.000 Floor is 21 Ceiling is 21

Enter number (-1 to quit): 47

running average is 110 / 4 = 27.500 Floor is 27 Ceiling is 28

Enter number (-1 to quit): 51

running average is 161 / 5 = 32.200 Floor is 32 Ceiling is 33

Enter number (-1 to quit): 63

running average is 224 / 6 = 37.333 Floor is 37 Ceiling is 38

Enter number (-1 to quit): -1

red 309 %

Assume all the inputs are valid.

Submit your program using submit 2031ON lab4 runningAveLocal.c

.out or, use websubmit

Problem A3 Variables (10 pts)

Specification

Modify the above program, simplifying communications between functions.

Implementation

• download program runningAveLocal2.c.

Any name is okay

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• define a function void r_avg(int input),which, given the current input input,

computes and displays the running average. Notice that unlike the function in A2, this

function takes only one argument about current input and does not take current sum and

input count as its arguments. In such an implementation, current sum and input count are

not maintained in main. Instead, main just pass current input to r_avg(), assuming

that r_avg() somehow maintains the current sum and input count info.

• do not modify or add to the code in main().

• do not use any global variable. How can function r_avg maintain the current sum and

input count info?

Sample Inputs/Outputs:

Same as in problem A2.

Submit your program using submit 2031ON lab4 runningAveLocal2.c

or, use websubmit

Problem A4 Variables (10pts)

Specification

Modify the program above, further simplifying communications between functions by using

global variables.

Implementation

• download program runningAveGlobal.c. Complete the main()function.

• download program function.c. Complete function void r_avg(), which computes

and displays the running average. Notice that this function takes no arguments.

• define all global variables in function.c

Sample Inputs/Outputs:

Same as in problem A2.

Submit your program using

submit 2031ON lab4 runningAveGlobal.c function.c

or, use websubmit

In the rest of this lab you are going to practice using some C library functions. The simplified

prototypes of the functions covered in this week’s lecture are listed below:

<string.h>

int strlen(s)

s strcpy(s,s)

s strcat(s,s)

int strcmp(s,s)

<ctype.h>

int islower(int)

int isupper(int)

int isalpha(int)

int isdigit(int)

int isxdigit(int)

int tolower(int)

int toupper(int)

<stdlib.h>

int atoi(s)

double atof(s)

long atol(s)

int rand(void)

int abs(int)

system(s)

exit(int)

<stdio.h>

printf()

scanf()

getchar()

putchar()

sscanf()

sprintf()

fgets()

fputs()

<math.h>

sin() cos()

double exp(x)

double log(x)

double pow(x,y)

double sqrt(x)

double ceil(x)

double floor(x)

6

For exact prototypes of these functions, you can either 1) issue man 3 function_name in

the terminal. 2) look at Appendix B of the required textbook.

You are encouraged to use these functions when appropriate, especially string functions

declared in <string.h> as well as string-related IO functions declared in <stdio.h>.

Don’t forget to include the corresponding header files. Moreover, if you use functions

declared in <math.h>, then on the lab environment you need to link the library by using –lm

flag of gcc. That is, gcc x.c -lm

Problem B0 String manipulations, Library functions

Download file lab4B0.c. This short program first creates a character array and then uses

string library function strcpy and strcat to change the content of the array. Observe that,

• we need to include <string.h> in order to use the string library functions.

• char array without initialization contains random values on some system (e.g., our lab). So

don’t assume it is initialized with all \0 characters.

• strcpy(s1, s2) always copies whole source string s2 (from the beginning to the first \0

character -- inclusive) to the beginning of destination string s1.

o strncpy(s1, s2, n) copies first n character of course string s2 to the beginning

of s1. If the first n character does not include the \0 of the s2, (i.e., n ≤

strlen(s2)), then no \0 is copied to the destination string s1.

• strcat(s1, s2) always appends whole s2 (from the beginning to the first \0 character -

- inclusive) to the end of s1. s1 may contain some characters so where is the end of s1?

Starting from beginning of the array (the left end), the first \0 in s1 is considered the end of

s1, thus the first character of s2 replaces the first \0 character in s1, gluing s1 and s2.

o strncat(s1, s2, n) appends the first n character of s2 to the end of s1. It

always adds a \0 at the end of the n character (even if n ≤ strlen(s2)),

terminating the destination string.

• strlen(s) and printf("%s",s) also treat the first \0 of s as the end of the string.

For more information about the library functions, type man followed by the function name in

your terminal (man is a Unix command that stands for ‘manual’), e.g., man strcat

No submission for problem B0.

Problem B1 String manipulations, Library functions (10 pts)

Specification

Implement your version of strcat, called my_strcat.

Implementation

Download file lab4strcat.c. This program reads two words (strings with no spaces) from

the user, stored them into arrays a and b. It then copies the inputs into another two arrays c

and d, using library function strcpy. Then it calls strcat to concatenate a and b, and calls

my_strcat to concatenate c and d. If implemented correctly, a and c should have the same

content. The program terminates when user enters two xxx.

• Implement function void my_strcat(char []). Obviously, function should not call

library function strcat. Also should not create extra temporary arrays in the function.

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• Complete the while loop so that it keeps on prompting the user for inputs, and terminates

when both two input strings are xxx, as shown in the sample output. Use strcmp library

function to check the termination condition.

Sample input, output (assume each input has less than 30 characters and contains no space.)

red 118 % a.out

hello

worlds

strcat: helloworlds

mystrcat: helloworlds

good

ok

strcat: goodok

mystrcat: goodok

hi

g

strcat: hig

mystrcat: hig

goodluck

thanks

strcat: goodluckthanks

mystrcat: goodluckthanks

xxx

good

strcat: xxxgood

mystrcat: xxxgood

yy

xxx

strcat: yyxxx

mystrcat: yyxxx

xxx

xxx

red 119 %

Submit your program using submit 2031ON lab4 lab4strcat.c

or, use websubmit

Both strcpy(s,t), strcat(s,t), and my_strcat(s,t) modify the actual array pass to the

function, by modifying s. Do you think that this is strange, given that in C everything is pass

by value? Recall that void increment(int x) or void swap(int x, int y) would never

work, as x and y are just local copies of actual arguments. Isn’t s just a local copy of the

corresponding actual argument too? Think about this, we will talk about this soon.

Problem B2 String manipulations, Library functions (15 pts)

Introduction

Consider the string library function strcmp(s,t). In Java there is a similar method

string.compareTo(s). This function determines if s lexicographically precedes t (i.e., if

s appears earlier than t in dictionary). It does so by comparing the two strings character by

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character. Issue man strcmp in the terminal , or search online resources to see how they work

in C and Java

http://www.cplusplus.com/reference/cstring/strcmp/

https://www.geeksforgeeks.org/strcmp-in-c-cpp/

https://www.programiz.com/c-programming/library-function/string.h/strcmp

https://overiq.com/c-programming-101/the-strcmp-function-in-c/

https://docs.oracle.com/javase/8/docs/api/java/lang/String.html#compareTo-java.lang.StringSpecification

Implement your version of strcmp, called my_strcmp, which does the same comparison.

Implementation

Download file lab4strcmp.c. This program reads two strings from the user, calls library

function strcmp to compare their lexicographical ordering, and then calls function my_strcmp

to compare the lexicographic ordering again.

The program terminates when user enters two xxx.

• Implement function int my_strcmp(char []). Obviously, the function should not

call library function strcmp. Note that your function doesn’t have to return exactly the

same value as strcmp -- it needs to return a value that has the same sign as those

returned by strcmp.

• Complete the while loop so that it keeps on prompting user for inputs, and terminates when

both two input strings are xxx, as shown in the sample output. Use function strcmp or

my_strcmp to check.

Sample input and output

red 118 % a.out

apple

beast

strcmp: "apple" appears earlier in dictionary than "beast"

mystrcmp: "apple" appears earlier in dictionary than "beast"

ace

ave

strcmp: "ace" appears earlier in dictionary than "ave"

mystrcmp: "ace" appears earlier in dictionary than "ave"

exit

exam

strcmp: "exit" appears later in dictionary than "exam"

mystrcmp: "exit" appears later in dictionary than "exam"

exam

exam

"exam" and "exam" are same

"exam" and "exam" are same

exam

examine

strcmp: "exam" appears earlier in dictionary than "examine"

mystrcmp: "exam" appears earlier in dictionary than "examine"

9

examination

exam

strcmp: "examination" appears later in dictionary than "exam"

mystrcmp: "examination" appears later in dictionary than "exam"

xxx

hello

strcmp: "xxx" appears later in dictionary than "hello"

mystrcmp: "xxx" appears later in dictionary than "hello"

xxx

xxx

red 119 %

Submit your program using submit 2031ON lab4 lab4strcmp.c

or, use websubmit

Problem C String manipulations, Library functions (10 pts)

Specification

Develop an ANSI-C program that reads user information from the standard inputs, and outputs

the modified version of the records.

Implementation

Download file lab4fgets.c and start from there. Note that the program

• uses loop to read inputs (from standard in), one input per line, about the user information in

the form of name age rate, where name is a word (with no space), age is an integer

literal, and rate is a floating point literal. See sample input below.

• uses fgets() to read in a whole line at a time.

As discussed earlier, since the input contains space, using scanf("%s", inputArr)

does not work here, as scanf stops at the first blank (or new line character if no space).

Consequently, if user enters Joe 2 2.3, only Joe is read in.

As mentioned in this week’s class, in order to read a whole line of input which may contain

blanks, you can use scanf("%[^\n]s",inputsArr),or, depreciated function

gets(inputsArr), but a much more common approach is to use function fgets().

Both these functions are declared in stdio.h.

fgets(inputsArr, n, stdin) reads a maximum of n characters from stdin

(Standard input) into array inputsArr.

The program should,

• after reading each line of inputs, if it is not "exit", output the original input using printf

and fputs. Notice that since fgets reads in a '\n' at the end of input, printf does not

need \n in the formatting string.

• then create a char array resu for the modified version of the input. In the modified version

of input, the first letter of name is capitalized, age becomes age + 10, and rate has 100%

increases with 3 digits after decimal point, followed by the floor and ceiling of the increase

rate. The values are separated by dashes and brackets as shown below. the

• then output the resulting string resu.

• continue reading input, until a line of exit is entered. (How

10

Hints:

• When fgets reads in a line, it appends a new line character \n at the end (before \0). Be

careful about this when checking if the input is exit.

• To create resu, you may want to tokenize the original input first. To tokenize a string,

consider sscanf

• To create resu from several variables, consider sprintf.

• If you use math library functions, be aware that the return type is double. Also if you run

the program in our lab environment, need to compile the program using -lm flag of gcc.

Sample Inputs/Outputs:

red 118 % a.out

Enter name, age and rate: sue 22 33.3

sue 22 33.3

sue 22 33.3

Sue-32-66.600-[66,67]

Enter name, age and rate: john 60 1.0

john 60 1.0

john 60 1.0

John-70-2.000-[2,2]

Enter name, age and rate: lisa 30 1.34

lisa 30 1.34

lisa 30 1.34

Lisa-40-2.680-[2,3]

Enter name, age and rate: judy 40 3.2

judy 40 3.2

judy 40 3.2

Judy-50-6.400-[6,7]

Enter name, age and rate: exit

red 119 %

Submit your program using submit 2031ON lab4 lab4fgets.c

or, use websubmit

Problem D0. 2D array, Library functions.

Download file lab4twoDarray.c. This short program demonstrates how to create, initialize

2D arrays, and access array elements. Read and run the program, and observe

• the size of the 2D arrays.

• how to access 2D arrays at cell (element) level, using [][].

• that, for char 2D array, each row is essentially a 1-d char array (i.e., a string if it is \0

terminated). So each row can be feed into string library functions and printf directly, e.g.,

strlen(b[1]) strcpy(b[2], "Hello") printf("%s", b[i]). As a

result, example, we can print the char 2D array with one loop, whereas we use two loops for

printing int 2D array.

No submission for this part, but understanding this program gets you prepared for the next two

exercise.

11

Problem D1. 2D array, Library functions. (20 pts)

Specification

Write an ANSI-C program that reads user information from the standard inputs, and outputs

both the original and the modified version of the records.

Implementation

A file lab4table1.c is for you to get started. The program should:

• use a table-like 2-D array (i.e., an array of ‘strings’) to record the inputs.

• use loop and scanf("%s %s %s") to read inputs (from standard in), one input per line,

about the user information in the form of name age rate, where name is a word (with

no space), age is an integer literal, and rate is a floating point literal. See sample input

below.

• store each input string into the current available ‘row’ of the 2D array, starting from row 0.

• create a modified string of the input, and store it in the next row of the 2D array. In the

modified version of input, all letters in name are capitalized, age becomes age + 10, and

rate has 50% increases and is formatted with 2 digits after decimal point.

• continue reading input, until a name xxx is entered, followed by any age and rate values.

• after reading all the inputs, output the 2-D array row by row, displaying each original input

followed by the modified version of the input.

• display the current date and time and program name before generating the output, using

predefined pre-processor macros such as __FILE__, __TIME__ (implemented for you).

•

Note that as the partial implementation shows, each input line is read in as three ‘strings’ using

scanf("%s %s %s", ….). In the next question, you will practice reading in the whole line as

a string, as in lab4fgets (and then tokenize the string). Each approach has its pros and cons.

Note that you will lose all marks if, instead of a 2D-array, you use 3 parallel 1-D arrays -- one

of names, one of ages, one for wages -- to store and display information.

Sample Inputs/Outputs:

red 307 % a.out

Enter name, age and rate: john 60 1.0

Enter name, age and rate: eric 30 1.3

Enter name, age and rate: lisa 22 2.2

Enter name, age and rate: Judy 40 3.2254

Enter name, age and rate: xxx 2 2

Records generated in lab4table1.c on Feb 10 2021 13:32:48

row[0]: john 60 1.0

row[1]: JOHN 70 1.50

row[2]: eric 30 1.3

row[3]: ERIC 40 1.95

row[4]: lisa 22 2.2

row[5]: LISA 32 3.30

row[6]: Judy 40 3.2254

row[7]: JUDY 50 4.84

red 308 %

Sample Inputs/Outputs: (download file inputD.txt)

red 309 % a.out < inputD.txt

12

Enter name, age and rate: Enter name, age and rate: Enter name, age

and rate: Enter name, age and rate: Enter name, age and rate: Enter

name, age and rate:

Records generated in lab4table1.c on Feb 10 2021 13:42:03

row[0]: john 60 1.0

row[1]: JOHN 70 1.50

row[2]: Sue 30 1

row[3]: SUE 40 1.50

row[4]: Lisa 22 2.2

row[5]: LISA 32 3.30

row[6]: JuDy 40 3.22

row[7]: JUDY 50 4.83

row[8]: eric 30 1.3345

row[9]: ERIC 40 2.00

red 310

Submit your program using submit 2031ON lab4 lab4table1.c

or, use websubmit

Problem D2. 2D array, library functions. (20 pts)

Specification

Same question as problem D1 but now you read each line of input as a whole line of string.

A file lab4table2.c is created for you to get started.

As the code shows, reading a whole line allows the input to be read into a table row directly. So

you don’t have to store the original input into the table manually. The disadvantage, however, is

that you may need to tokenize the line in order to get the name, age and rate information.

Sample Inputs/Outputs:

Same output as above, except that the generated file name is lab4table2.c now, and the

time is different.

Submit your program using submit 2031ON lab4 lab4table2.c

or, use websubmit

Problem E Pointer 101 (10 pts)

Specification

Write your first (short) program that uses pointers.

Implementation

• define an integer age and initialize it to 10. Define another integer age2, which is initialized

to 100;

• define an integer pointer variable ptr, and make it point to age

• display the value of age, both via age (direct access), and

via pointer ptr (indirect access).

• use ptr to change the value of age to 14;

• confirm by displaying the value of age, both via age and via its pointer ptr

• define another pointer variable ptr2, and make it point to age2

• assign triple of age’s value to age2 via pointer ptr and ptr2 (i.e.,

without referring to age and age2). age2 is 42 now.

ptr age

*

ptr2 age2

*

13

• display the value of age2, both via age2, and via its pointer ptr2

• now let ptr2 point to age (too) by getting the address of age

from pointer variable ptr (i.,e., without using &age)

• confirm by displaying the value of ptr2’s pointee via ptr2

• display value of age, both from age, and via ptr and ptr2.

• use ptr2 to decrease the value of age by 1. age is 13 now.

• display value of age, both from age, and via ptr and ptr2.

• finally, display the address of age, using printf("%p %p %p\n",&age,ptr,ptr2);

Notice that here we print prt and ptr2 directly. This displays the content of the pointer

variables, which is the address of age (in Hex).

Sample Inputs/Outputs:

red 305 % a.out

age: 10 10

age: 14 14

age2: 42 42

ptr2’s current pointee: 14

age: 14 14 14

age: 13 13 13

0x7ffd04a92bcc 0x7ffd04a92bcc 0x7ffd04a92bcc

red 306

Submission:

Name your program lab4pointer.c and submit using

submit 2031ON lab4 lab4pointer.c

or, use websubmit

In summary, in this lab you should submit

File_for_the_degugger_problem

runningAveLocal.c runningAveLocal2.c

runningAveGlobal.c function.c

lab4strcat.c lab4strcmp.c

lab4fgets.c

lab4table1.c lab4table2.c

lab4pointer.c

You can submit using websubmit at https://webapp.eecs.yorku.ca/submit/

o Login using you eecs user name

o If you keep on getting passport York login page when following the link, clear the

browsing history, cache and cookie of your browser, and then try the link again.

You may want to issue submit -l 2031ON lab4 to view the list of files that you have

submitted.

ptr2 age2

*

ptr age

*

You will get different

numbers here but they should

be identical to each other.

This is the memory address of

variable age, in Hex.

Lower case L

Any name is okay

14

Common Notes

All submitted files should contain the following header:

/***************************************

* EECS2031ON – Lab4 *

* Author: Last name, first name *

* Email: Your email address *

* eecs_username: Your eecs login username *

* York num: Your York student number

****************************************/

In addition, all programs should follow the following guidelines:

• Include the stdio.h library in the header of your .c files.

• Assume that all inputs are valid (no error checking is require ed).