Project 2.2 on Arrays and C-Strings

Objective

In this challenge, you will write a program that prints the length of a string passed in via argument 1 without using the c-string library (string.h)

Program Overview

• Create a function that returns the length of the C-string passed to it.
• The trick to this function is remembering that all properly formed C-strings end with a null terminator, which is \x00, \0, 0.
• The code might use a while loop that moves through each character in the C-string until it encounters a null string terminator.
• The string_length function will take input from main's argument 1
• It will print out the argument
• It will call string_length
• Then it will print out the string length

Steps to complete

• Follow the CODE: instructions provided in main.c
• Write a user test that tests the program's length function (user_tests/utest3.1.json)
• Run /challenge/tester to get the flag

Objective

I'm learning to program, please explain every step to me like I'm a child and talk directly to me through the comments but make it fun

In this challenge, you will write a program that concatenates two strings provided by arguments 1 and 2 without using the c-string library (string.h)

Program Overview

• Create a function that concatenates 2 c-strings.
• Pass arg1 and arg2 to the new function
• Print out the concatenated strings

Steps to complete

• Copy the string_length function from level 1, by using cat on the main.c from the prior level, which is located at ../01/main.c
• In the main function , which must receive command parameters argc and argv
  • Check to make sure that only 2 command line arguments are used (i.e., argc equals 3, one for name of binary, and 2 given by user)
  • if the number of arguments are incorrect then
  • printf("Error wrong number of parameters, usage: %s arg1 arg2\n", argv[0]);
  • return 99
  • print "The received strings are arg1=\"%s\" arg2=\"%s\"\n" where the %s's are arg1 and arg2
  • declare a c-string of size 100 and named cstr and initialize it to ""
  • concatenate argument 1 to cstr
  • concatenate argument 2 to cstr
  • print "The concatenated string is \"%s\"\n"

    add the statement to the end, puts("That's all for katkat\n")

• void concatenate_strings(char str1[], char str2[])
  • The function copies str2 to the end of str1 *
• if you want you may copy the string_length function from the prior level.
• Write a user test that tests the program's length function (user_tests/utest3.2.json)
• To use a double quote in the test case, it must be escaped, "which is done like \"this\"."
• Run /challenge/tester to get the flag

Objective

In this challenge, you will write a program that copies arg1 to the variable cstr and then prints the cstr value without using the c-string library (string.h).

Program Overview

• Create a function that copies the second c-string over the first.
• If only 1 argument is provided copy the input into a local variable for up to 50 characters (default value)
• If 2 arguments are provided, use the second argument as the max length to copy
• Copy the argument using the copy function
• Print out the copied variable

Steps to complete

• Copy the string_length function from level 1, by using cat on the main.c from the prior level, which is located at ../01/main.c
• Follow the CODE: instructions provided in main.c
• Write a user test that tests the program's length function (user_tests/utest3.3.json)
• Run /challenge/tester to get the flag

Objective

In this challenge, you will write a program that compares arg1 to arg2 and prints the result without using the c-string library (string.h).

Program Overview

• Write a function that will compare 2 strings
• Call the function using arg arg1 and arg2
• It will print 0 if they match exactly.
• It will print a negative value if the mismatching character of arg2 is larger than the character in arg1.
• It will print a positive value if the mismatching character of arg2 is smaller than the character in arg1.

Steps to complete

• Copy the string_length function from level 1, by using cat on the main.c from the prior level, which is located at ../01/main.c
• Follow the CODE: instructions provided in main.c
• Run /challenge/tester to get the flag

Objective

In this challenge, you will write a program that changes vowels to upper case letters without using the c-string library (string.h).

Program Overview

• Create a function that will change the vowels in a word to upper case
• The program will use arg1 as a filename
• It will read from the file
• It will pass the input to the function and change all vowels to upper case
• It will join together all the words on a single line and with a space between each word
• Once done mangling all the words, it will print them all at at once.

Steps to complete

• Copy the string_length and concatenate_strings functions from level 2, by using cat on the main.c from the prior level, which is located at ../02/main.c
• Follow the CODE: instructions provided in main.c
• Write a user test that tests the program's length function (user_tests/utest3.5.json)
• Run /challenge/tester to get the flag

Objective

Your task is to review, identify, and fix errors in the provided C code .

Program Should Complete the Following

• Take a list of numbers as input from a file provided via argument 1
• Calculate the average of the numbers.
• Find the highest and lowest numbers.
• Print out the average, highest, and lowest numbers.

Steps to complete

• Create 3 test cases:
  • 6.1 tests the average value
  • 6.2 tests the highest number value
  • 6.3 tests the lowest number value
• Fix the bugs in the code so that it meets the system and user tests

Hints:

• Some loops might have wrong conditions or variable names (verify the < and <= are doing what you expect)
• Add a print statement to check that the accumulation for the average is the proper value
• Look for undeclared or incorrectly declared variables.

Objective

Use the debugger to get the flag

Steps to complete

• Open the main.c for level 07 in vscode
• Run the debugger in vscode
• Get the flag from the variable after it's loaded into memory

Steps to print out a variable

• To print a variable out in a way that you can copy and paste, switch to the debug console (bottom pane)
• Type in (char *) buffer or -exec print buffer
• Copy and paste your flag

Objective

Use the debugger to get the flag

Steps to complete

• Open the main.c for level 08 in vscode
• Run the debugger in vscode
• Get the flag from the variable after it's loaded into memory

Steps to print out a variable (see prior challenge)

Steps to change a variable

• Find a good place to stop the execution with a breakpoint
• Via the gui: double click on the variable and change the value (for characters completely remove the value and replace with 'c')
• Via the debugger console: use the command -exec set variable a = 99

Objective

Use valgrind to locate the origin of the segmentation faults (2) in this blackjack game.

Steps to complete

• Compile main.c with debugging enabled -g
• Run main.bin using valgrind
• Read valgrind's output looking for the segmentation fault, which will be similar to

  Process terminating with default action of signal 11 (SIGSEGV) 
    

• Fix the code, recompile, and try again
• Use tester to test your code and get the flag