added weekly exercises of isp-ws25

c/isp-ws25/weeklies/week07/w07ex01.c

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+/*
+In this task, you should get familiar with malloc() and free().
+In addition, you should implement the functions
+- fillArray(int size, int base_number)
+- printArray(int* numbers, int size).
+
+main:
+- user can enter the size of the integer array
+- user can enter the base number that is used to fill the array
+- print "Memory allocation failed\n" if memory allocation in fillArray failed
+- immediately return exit code 1
+- free the allocated memory using free() at the end.
+
+call createAndFillArray(int size, int base_number)
+- create array by allocating enough memory for it on the heap using malloc()
+- if memory allocation is not successful, return NULL
+- After allocating fill the array with integer values
+  with multiples of base_number using pointer arithmetic
+- Return pointer to array at the end of the function
+
+call printArray(int* numbers, int size)
+- print the array using pointer arithmetic
+
+Examples:
+
+Size: 5
+Fill numbers array with multiples of: 3
+3 6 9 12 15
+
+Size: 4
+Fill numbers array with multiples of: 5
+5 10 15 20
+
+Size: 12
+Fill numbers array with multiples of: 100
+100 200 300 400 500 600 700 800 900 1000 1100 1200
+*/
+
+#include <stdio.h>
+#include <stdlib.h> // TODO: Include the required header file
+
+int* createAndFillArray(int size, int base_number)
+{
+  // TODO: Allocate memory
+  int *numbers = (int*) malloc( size * sizeof(int) );
+  // TODO: Check if memory could be allocated
+  if ( numbers == NULL ) return NULL;
+
+  // TODO: Fill the array with multiples of base_number using pointer arithmetic and return it
+  for ( int position = 0 ; position < size; position++ )
+  {
+    *(numbers + position) = base_number * ( position + 1 );
+  }
+
+  return numbers;
+}
+
+void printArray(int* numbers, int size)
+{
+  for (int position = 0; position < size; position++)
+  {
+    printf("%d ", *(numbers + position));
+  }
+  // TODO: Print the array using pointer arithmetic
+}
+
+int main(void)
+{
+  int size = 0;
+  printf("Size: ");
+  scanf("%d", &size);
+  
+  int base_number = 0;
+  printf("Fill numbers array with multiples of: ");
+  scanf("%d", &base_number);
+
+  int* numbers = createAndFillArray(size, base_number);
+  if ( numbers == NULL )
+  {
+    printf("Memory allocation failed\n");
+    return 1; // TODO: Return 1 if the memory allocation was not successful
+  }
+
+  printArray(numbers, size);
+
+  free(numbers); // TODO: Free the allocated memory
+
+  return 0;
+}

c/isp-ws25/weeklies/week07/w07ex02.c

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+/*
+In this task, you should get familiar with calloc() and free().
+The program tracks the attendance of students.
+The user can enter the number of students and then mark certain students as present.
+
+Use calloc() to allocate memory on the heap for the required number of students.
+All students are marked as absent by default since calloc() initializes by default with 0.
+If the memory allocation is not successful, print Memory allocation failed\n and immediately return the exit code 1.
+
+After allocating the memory, the user can enter student numbers (1-based, not 0-based) to mark them as present.
+When a student number is entered, the program should mark the corresponding student as present.
+Any student numbers that are not within the range of all student numbers
+(i.e., 1 to the entered number of students) should be ignored.
+If the user enters 0, the attendance check is done and the program prints the attendance record.
+For each student, print if the student is present or absent.
+
+Don’t forget to free the allocated memory using free() at the end of the main() function.
+
+Examples:
+
+Number of students: 12
+Enter student numbers to mark as present (1 to 12, 0 to end):
+1
+8
+4
+5
+3
+0
+Attendance record:
+Student 1: Present
+Student 2: Absent
+Student 3: Present
+Student 4: Present
+Student 5: Present
+Student 6: Absent
+Student 7: Absent
+Student 8: Present
+Student 9: Absent
+Student 10: Absent
+Student 11: Absent
+Student 12: Absent
+*/
+
+#include <stdio.h>
+#include <stdlib.h> // TODO: Include the required header file
+#include <stdbool.h>
+
+#define ganzzahl int
+#define gleitkomma float
+#define leere void
+#define NICHTS ((void*)0)
+#define schreibf printf
+#define liesf scanf
+#define falls if
+#define fuer for
+#define solange while
+#define mach do
+#define mach_weiter continue
+#define gib_zurueck return
+#define haupt main
+#define befreie free
+#define unsigniert unsigned
+
+
+ganzzahl* erstelleFeld ( ganzzahl anzahl_an_schuelern )
+{
+  ganzzahl *studenten = (ganzzahl*) calloc(anzahl_an_schuelern,sizeof(ganzzahl));
+  falls(studenten == NICHTS) gib_zurueck NICHTS;
+  gib_zurueck studenten;
+}
+
+leere liesAnwesenheit ( ganzzahl* anwesenheit_der_studenten, ganzzahl anzahl_an_schuelern)
+{
+  ganzzahl schueler = 0;
+  schreibf("Enter student numbers to mark as present (1 to %d, 0 to end):\n", anzahl_an_schuelern); // TODO: Mark students as present
+  ganzzahl benutzereingabe = 0;
+  mach
+  {
+    liesf("%d", &benutzereingabe);
+    schueler++;
+    falls(benutzereingabe == 0) gib_zurueck;
+    falls(benutzereingabe < 0) mach_weiter;
+    falls(benutzereingabe > anzahl_an_schuelern - 1) mach_weiter;
+    anwesenheit_der_studenten[benutzereingabe-1] = 1;
+  }solange(benutzereingabe != 0 && schueler < anzahl_an_schuelern);
+}
+
+leere schreibAnwesenheit ( ganzzahl* anwesenheit_der_studenten, ganzzahl anzahl_an_schuelern )
+{
+  schreibf("Attendance record:\n");
+
+  fuer(ganzzahl schueler = 1; schueler <= anzahl_an_schuelern; schueler++)
+  {
+    schreibf("Student %d: %s\n", schueler, anwesenheit_der_studenten[schueler-1] == 0 ? "Absent" : "Present");
+  }
+  // TODO: Print the attendance record
+}
+
+ganzzahl haupt(leere)
+{
+  ganzzahl anzahl_an_schuelern = 0;
+
+  schreibf("Number of students: ");
+  liesf("%d", &anzahl_an_schuelern);
+
+  ganzzahl* anwesenheit = erstelleFeld(anzahl_an_schuelern); // TODO: Allocate memory
+  falls ( anwesenheit == NICHTS ) { // TODO: Check if memory could be allocated
+    schreibf("Memory allocation failed\n");
+    gib_zurueck 1;
+  }
+
+  liesAnwesenheit(anwesenheit, anzahl_an_schuelern);
+
+  schreibAnwesenheit(anwesenheit, anzahl_an_schuelern);
+
+  befreie(anwesenheit); // TODO: Free the allocated memory
+
+  gib_zurueck 0;
+}