add initial c, cpp files

c/isp-ws25/a2-vowels.c

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+#include <stdio.h>
+#include <string.h>
+
+#define STRING_SIZE 30
+
+void inputString(char user_input[])
+{
+  printf("Please enter the string: ");
+  fgets(user_input, STRING_SIZE, stdin);
+}
+
+void countVowels(char user_input[], int vowels[])
+{
+    int position = 0;
+    while (user_input[position] != '\n')
+    {
+        if (user_input[position] == 'a' || user_input[position] == 'A') vowels[0]++;
+        if (user_input[position] == 'e' || user_input[position] == 'E') vowels[1]++;
+        if (user_input[position] == 'i' || user_input[position] == 'I') vowels[2]++;
+        if (user_input[position] == 'o' || user_input[position] == 'O') vowels[3]++;
+        if (user_input[position] == 'u' || user_input[position] == 'U') vowels[4]++;
+        position++;
+    }
+}
+
+void printVowels(int vowels[])
+{
+    printf("a: %d\n", vowels[0]);
+    printf("e: %d\n", vowels[1]);
+    printf("i: %d\n", vowels[2]);
+    printf("o: %d\n", vowels[3]);
+    printf("u: %d\n", vowels[4]);
+}
+
+int main(void)
+{
+  char user_input[STRING_SIZE] = {'\0'};
+  int vowels[5] = {0};
+  
+  inputString(user_input);
+  
+  countVowels(user_input, vowels);
+  
+  printVowels(vowels);
+
+  return 0;
+}

c/isp-ws25/a4-insert-in-sorted-list.c

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+/******************************************************************************
+Student Management Using Linked Lists
+
+Task Description
+In this coding task, you will extend a student management system. The program already creates students and stores them in a sorted linked list. Your task is to implement the functionality of adding additional students into the sorted linked list.  Some parts of the program are already implemented.
+
+Key points:
+Already Implemented: The student struct is defined. Students are created in the main function and added manually into a linked list.
+Your task: The function insertSorted should insert a student into the existing linked list at the correct position. 
+The linked list is sorted alphabetically by student names.
+
+Hints:
+How to find the position to insert?
+Stop iterating over the linked list at the element before the one you want to insert.
+In the visualization above, we insert "Benedikt" after "Andreas" and before "Daniel". Stop at "Andreas" and change the pointers accordingly.
+Consider the case of adding the student in the middle of the linked list, but also at the end and at the head (index to insert = 0)
+Have a look at the testcases
+
+Implement the following functions:
+
+-> insertSorted(Student *list, Student *new_student)
+
+This function takes two arguments:
+i) a pointer to the current list of students (list),
+ii) a pointer to the students to insert into the list.
+Add the student into the existing linked list at the correct position.
+The linked list is sorted alphabetically by name. 
+The function should return the head of the linked list.
+
+-> freeStudents(Student *list)
+
+Free all students in the linked list.
+This is tested with valgrind checks at testcase 2 and 3.
+The function should not return anything.
+
+Specifications
+Use dynamic memory allocation
+The program must compile and run without memory leaks/errors.
+Use the existing Linked List.
+You don't need to modify the structs or the print function. 
+You don't have to consider the case where no more memory is available. 
+*******************************************************************************/
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+typedef struct Student
+{
+  char name_[32];
+  struct Student *next_;
+} Student;
+
+Student* createStudent(char* name)
+{
+  Student *s = malloc(sizeof(Student));
+  if (!s) return NULL;
+  strcpy(s->name_, name);
+  s->next_ = NULL;
+  return s;
+}
+
+void printStudents(Student *list)
+{
+  Student *cur = list;
+  int index = 0;
+  while (cur != NULL)
+  {
+    printf("%d: %s\n", index++, cur->name_);
+    cur = cur->next_;
+  }
+}
+
+// TODO: write your code here
+Student *insertSorted(Student *list, Student *new_student)
+{
+    Student *current = list;
+    Student *previous = NULL;
+    
+    while(current != NULL && strcmp(current->name_, new_student->name_) <= 0)
+    {
+        previous = current;
+        current = current->next_;
+    }
+    
+    if(previous == NULL)
+    {
+        new_student->next_ = current;
+        list = new_student;
+    }
+    else
+    {
+        new_student->next_ = current;
+        previous->next_ = new_student;
+    }
+    
+    return list;
+}
+
+void freeStudents(Student *list)
+{
+    if (!list) return;
+    
+    freeStudents(list->next_);
+    free(list);
+    list = NULL;
+}
+// TODO: write your code here
+
+int main(void)
+{
+  int test;
+  printf("Enter tc: ");
+  scanf("%d", &test);
+  if(test == 1)
+  {
+    // test adding at the second and third position
+    Student* s1 = createStudent("Andreas");
+    Student* s2 = createStudent("Daniel");
+    s1->next_ = s2;
+
+    Student* to_add1 = createStudent("Benedikt");
+    Student* to_add2 = createStudent("Clemens");
+
+    s1 = insertSorted(s1, to_add1);
+    s1 = insertSorted(s1, to_add2);
+    printStudents(s1);
+    //freeStudents(s1); // uncomment that after you implemented the function
+  }
+  else if(test == 2)
+  {
+    // test adding at same first character (T)
+    Student* s1 = createStudent("Benjamin");
+    Student* s2 = createStudent("Tanja");
+    Student* s3 = createStudent("Thomas");
+    s1->next_ = s2;
+    s2->next_ = s3;
+
+    Student* to_add1 = createStudent("Toni");
+    Student* to_add2 = createStudent("Tamim");
+
+    s1 = insertSorted(s1, to_add1);
+    s1 = insertSorted(s1, to_add2);
+    printStudents(s1);
+    //freeStudents(s1); // uncomment that after you implemented the function
+  }
+  else if(test == 3)
+  {
+    // test adding in the beginning and end of the LL
+    Student* s1 = createStudent("Lenon");
+    Student* s2 = createStudent("Margarita");
+    s1->next_ = s2;
+
+    Student* to_add1 = createStudent("Julia");
+    Student* to_add2 = createStudent("Kilian");
+
+    s1 = insertSorted(s1, to_add1);
+    s1 = insertSorted(s1, to_add2);
+    printStudents(s1);
+    //freeStudents(s1); // uncomment that after you implemented the function
+  }
+
+  return 0;
+}