//CSE240 Fall 2018 HW4 // Enter your name here // State the IDE that you use: Visual Studio or GCC #include  #include  #pragma warning(disable : 4996) // compiler directive for Visual Studio only // Read before you start: // You are given a partially complete program. Your job is to complete the functions in order for this program to work successfully. // All instructions are given above the required functions, please read them and follow them carefully. // You shoud not modify the function return types or parameters. // You can assume that all inputs are valid. Ex: If prompted for an integer, the user will input an integer. // You can use only the strlen() of strings.h library to check ctring length. Do not use any other string functions // because you are supposed to use pointers for this homework. // DO NOT use arrays to store or to index the characters in the string // Global Macro Values. They are used to define the size of 2D array of characters #define NUM_STRINGS 4 #define STRING_LENGTH 35 // Forward Declarations void initializeStrings(char[NUM_STRINGS][STRING_LENGTH]); void printStrings(char[NUM_STRINGS][STRING_LENGTH]); void encryptStrings(char[NUM_STRINGS][STRING_LENGTH], int); void decryptStrings(char[NUM_STRINGS][STRING_LENGTH], int); void printReversedString(char s[STRING_LENGTH]); int isValidPassword(char s[STRING_LENGTH]); // Problem 1: initializeStrings (5 points) // Use pointer p to traverse the 2D array of characters variable 'strings' (input from user in main() ) and set all characters in each // array to a null terminator so that there is a 4 row and 35 column 2D array full of null terminators. // The null terminator is represented by the character value '\0' and is used to denote the end of a string. void initializeStrings(char strings[NUM_STRINGS][STRING_LENGTH]) { char *ptr = &strings[0][0]; } // Problem 2: printStrings (5 points) // Use pointer p to traverse the 2D character array "strings" and print each of the contained strings. // See the example outputs provided in the word document. Each string should be printed on a new line. void printStrings(char strings[NUM_STRINGS][STRING_LENGTH]) { char *ptr = &strings[0][0]; } // Problem 3: encryptStrings (5 points) // Use pointer ptr to traverse the 2D character array 'strings' and encrypt each string in 1 step as follows- // 1) Shift the characters forward by the integer value of 'key'. // If the string is "hello" and key = 2, we will shift those characters forward in ASCII by 2 and the result will be "jgnnq". // Once the value of 'key' gets larger, you will extend past alphabetical characters and reach non-alphabetical characters. Thats ok. // NOTE: DO NOT encrypt the null terminator character. Use the null terminators to find the end string. void encryptStrings(char strings[NUM_STRINGS][STRING_LENGTH], int key) { char *ptr = &strings[0][0]; } // Problem 4: decryptStrings (5 points) // HINT: This should be very similiar to the encryption function defined above in Problem 3. // Use pointer ptr to traverse the 2D character array 'strings' and decrypt each string in 1 step as follows- // 1)Shift the characters backward by the integer value of 'key'. // NOTE: DO NOT decrypt the null characters. void decryptStrings(char strings[NUM_STRINGS][STRING_LENGTH], int key) { char *ptr = &strings[0][0]; } // Problem 5: reverseStrings (15 points) // Reverse the string s and print it, by using pointers. // Use pointer p and 'temp' char to swap 1st char with last, then 2nd char with (last-1) and so on.. // Finally print the reversed string at the end of this function // Hint: You might want to check if your logic works with even as well as odd length string. void printReversedString(char s[STRING_LENGTH]) { char temp; // not necessary to use this variable char *p = &s[0]; // pointer to start of string } // Problem 6: isValidPassword (15 points) // Return 1 if the password satisfies the requirements, else return 0. // Password requirements: atleast 5 characters long, should contain atleast one lower case char, atleast one uppercase char, // atleast one number and only numbers and letters. // Valid password examples: Asu123, Cse240, abCd9. Invalid password examples: ASU123, Cidse, Asu1 // Traverse through the string by using pointer p to check if all conditions are satisfied // Note that the password string contains char at the end when you press 'Enter' to enter the password. int isValidPassword(char s[STRING_LENGTH]) { char *p = &s[0]; // enter code here return 0; // remove this line when implementing this function. // it is added initially , so that the empty function does not give compile error. } // You should study and understand how this main() works. // *** DO NOT modify it in any way *** int main() { char strings[NUM_STRINGS][STRING_LENGTH]; // will store four strings each with a max length of 34 int i, key; char input[STRING_LENGTH]; printf("CSE240 HW4: Pointers "); initializeStrings(strings); for (i = 0; i < NUM_STRINGS; i++) { printf("Enter a string: "); // prompt for string fgets(input, sizeof(input), stdin); // store input string input[strlen(input) - 1] = '\0'; // convert trailing ' ' char to '\0' (null terminator) strcpy(strings[i], input); // copy input to 2D strings array } printf(" Enter a key value for encryption: "); // prompt for integer key scanf("%d", &key); encryptStrings(strings, key); printf(" Encrypted Strings: "); printStrings(strings); decryptStrings(strings, key); printf(" Decrypted Strings: "); printStrings(strings); getchar(); // flush out newline ' ' char printf(" Enter a string to reverse: "); // prompt for string fgets(input, sizeof(input), stdin); // store input string printReversedString(input); getchar(); // flush out newline ' ' char printf(" A password should be atleast 5 char long and should contain atleast one lower case char, atleast one uppercase char,"); printf(" atleast one number and only numbers and letters"); printf(" Enter a password to validate: "); // prompt for string fgets(input, sizeof(input), stdin); // store input string if(isValidPassword(input)) printf(" Password is valid"); else printf(" Password is NOT valid "); getchar(); // keep console open return 0; }