C-Kurs/(Pointer) Swapping/Musterlösung

1. Teilaufgabe

#include <stdio.h>


void swap(int *x, int *y) {

  int temp= *x;
  *x= *y;
  *y= temp;
}

   
int main(){
  

  int i= 1;
  int j= 2;

  printf("i: %i j: %i\n", i, j);

  swap(&i, &j);

  printf("i: %i j: %i\n", i, j);

  return 0;
}

2. Teilaufgabe

#include <stdio.h>


void swap(int *x, int *y) {

  int temp= *x;
  *x= *y;
  *y= temp;
}
  

void print_int_array(char* name, int* array, int size){

  int i;

  printf("%s:", name);
  for(i= 0; i<size; i++){
    printf(" %i", array[i]);
  }
  printf("\n");
}


int main(){
  

  int a[]= {1, 2, 3, 4};
  int b[]= {5, 6, 7, 8};

  int length= sizeof(a) / sizeof(int);
 
  print_int_array("a", a, length);
  print_int_array("b", b, length);

  int i;
  for(i=0; i<length; i++){
    swap(&a[i], &b[i]); 
  }

  print_int_array("a", a, length);
  print_int_array("b", b, length); 

  return 0;
}

3.Teilaufgabe

#include <stdio.h>


void swap(int **x, int **y) {

  int* temp= *x;
  *x= *y;
  *y= temp;
}


  
int main(){
 

  int i= 1;
  int j= 2;

  int* p1;
  p1= &i;

  int* p2;
  p2= &j;

  printf("------------------------------------------\n");
  printf("before swap:\n");
  printf("------------------------------------------\n");
  printf(" p1:\t%p\t p2:\t%p\n", p1, p2);
  printf("*p1:\t%10i\t*p2:\t%10i\n", *p1, *p2);
  printf("  i:\t%10i\t  j:\t%10i\n", i, j);
  
  swap(&p1, &p2);

  printf("------------------------------------------\n");
  printf("after swap:\n");
  printf("------------------------------------------\n");
  printf(" p1:\t%p\t p2:\t%p\n", p1, p2);
  printf("*p1:\t%10i\t*p2:\t%10i\n", *p1, *p2);
  printf("  i:\t%10i\t  j:\t%10i\n", i, j);
 
  return 0;
}

4.Teilaufgabe

#include <stdio.h>


void swap(int **x, int **y) {

  int* temp= *x;
  *x= *y;
  *y= t;
}

 
void print_int_array(char* name, int* array, int size){

  int i;

  printf("%s:", name);
  for(i= 0; i<size; i++){
    printf(" %i", array[i]);
  }
  printf("\n");
}


int main(){
  
  int a[]= {1, 2, 3, 4};
  int b[]= {5, 6, 7, 8};

  int length= sizeof a / sizeof(int);
  
  int *p1;
  p1 = &a[0]; 

  int *p2;
  p2 = &b[0];
  
  print_int_array("front", p1, length);
  print_int_array("back", p2, length);

  swap(&p1, &p2);

  print_int_array("front", p1, length);
  print_int_array("back", p2, length);
}

5. Teilaufgabe

#include <stdio.h>


void swap(void **x, void **y) {
  
  void *t = *x;
  *x = *y;
  *y = t;
}

void print_int_array(char* name, int* array, int size){

  int i;

  printf("%s:", name);
  for(i= 0; i<size; i++)
    printf(" %i", array[i]);
  printf("\n");
}

void print_float_array(char* name, float* array, int size){

  int i;

  printf("%s:", name);
  for(i= 0; i<size; i++)
    printf(" %f", array[i]);
  printf("\n");
}

int main(){
  

  int i= 1;
  int j= 2;

  int* pi;
  pi= &i;

  int* pj;
  pj= &j;

  printf("i: %i j: %i\n", *pi, *pj);

  swap((void*)&pi, (void*)&pj);

  printf("i: %i j: %i\n", *pi, *pj);

  int a[]= {1, 2, 3, 4};
  int b[]= {5, 6, 7, 8};
  
  // a and b are constant
  // alternatively, you can use calloc

  int *pa;
  pa = &a[0]; 

  int *pb;
  pb = &b[0];
 
  print_int_array("a", pa, sizeof(a)/sizeof(int));
  print_int_array("b", pb, sizeof(b)/sizeof(int));

  swap((void**)&pa, (void**)&pb);

  print_int_array("a", pa, sizeof(a)/sizeof(int));
  print_int_array("b", pb, sizeof(b)/sizeof(int));

  float x[]= {1.0, 2.0, 3.0, 4.0};
  float y[]= {5.0, 6.0, 7.0, 8.0};
  
  // x and y are constant
  // alternatively, you can use calloc

  float *px;
  px = &x[0]; 

  float *py;
  py = &y[0];
  
  print_float_array("x", px, sizeof(x)/sizeof(int));
  print_float_array("y", py, sizeof(y)/sizeof(int));

  swap((void**)&px, (void**)&py);

  print_float_array("x", px, sizeof(x)/sizeof(int));
  print_float_array("y", py, sizeof(y)/sizeof(int));

  return 0;
}