Quelltext der Seite 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= &i;
   int* 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= 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);
   
   // a and b are constant
   // alternatively, you can use calloc
 
   int *front= &a[0]; 
   int *back= &b[0];
   
   print_int_array("front", front, length);
   print_int_array("back ", back, length);
 
   swap(&front, &back);
 
   print_int_array("front", front, length);
   print_int_array("back ", back, length);
 
   return 0;
 }


5. Teilaufgabe

 #include <stdio.h>
 
 
 void swap(void **x, void **y) {
   
   void *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");
 }
 
 
 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* p1= &i;
   int* p2= &j;
 
   printf("i: %i j: %i\n", *p1, *p2);
 
   swap((void*)&p1, (void*)&p2);
 
   printf("i: %i j: %i\n", *p1, *p2);
 
   int a[]= {1, 2, 3, 4};
   int b[]= {5, 6, 7, 8};
   
   int length= sizeof(a) / sizeof(int);
  
   // a and b are constant
   // alternatively, you can use calloc
 
   p1= &a[0]; 
   p2= &b[0];
  
   print_int_array("a", p1, length);
   print_int_array("b", p2, length);
 
   swap((void**)&p1, (void**)&p2);
 
   print_int_array("a", p1, length);
   print_int_array("b", p2, length);
 
   float c[]= {1.0, 2.0, 3.0, 4.0};
   float d[]= {5.0, 6.0, 7.0, 8.0};
 
   length= sizeof(c) / sizeof(int);
   
   // c and d are constant
   // alternatively, you can use calloc
 
   float *p3= &c[0]; 
   float *p4= &d[0];
   
   print_float_array("x", p3, length);
   print_float_array("y", p4, length);
 
   swap((void**)&p3, (void**)&p4);
 
   print_float_array("x", p3, length);
   print_float_array("y", p4, length);
 
   return 0;
 }