Массивы,struct и всякое такое

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <math.h>
 
 
int main(int argc, char *argv[]) {
  srand(time(NULL));
  size_t i;
  float points[6][2];
  float radius, distance;
 
  for (i = 0; i < 6; ++i)
    printf("(%.2f, %.2f) ", points[i][0] = (rand() % 1001 - 500) / 100.,
                            points[i][0] = (rand() % 1001 - 500) / 100.);
  printf("\n");
 
  for (i = 0; i < 6; ++i)
    if (radius < (distance = pow(pow(points[i][0], 2.) +
                                 pow(points[i][1], 2.), 0.5)))
      radius = distance;
 
  printf("Radius = %f\n", radius);
 
  return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
 
enum Education { base, high, higher };
 
struct Stuff {
  size_t id;
  enum Education education;
  size_t children;
};
 
void PrintStuff(struct Stuff *stuff) {
  printf("Id: %d, education: ", stuff->id);
  switch (stuff->education) {
    case 0: printf("base, "); break;
    case 1: printf("high, "); break;
    case 2: printf("higher, "); break;
  }
  printf("children: %d.\n", stuff->children);
}
 
struct Stuff *RandomStuff(size_t id, struct Stuff *stuff) {
  stuff->id = id;
  stuff->education = rand() % 3;
  stuff->children = rand() % 3;
  return stuff;
}
 
int main(int argc, char *argv[]) {
  srand(time(NULL));
  size_t i;
 
  struct Stuff stuff[20];
  for (i = 0; i < 20; ++i)
    PrintStuff(RandomStuff(i, &stuff[i]));
 
  printf("Higher education with two children:\n");
 
  for (i = 0; i < 20; ++i)
    if (stuff[i].education == higher && stuff[i].children == 2)
      PrintStuff(&stuff[i]);
 
  return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
 
int main(int argc, char *argv[]) {
  srand(time(NULL));
 
  const float k_PI = 3.1415926535;
  int radius;
 
  do {
    printf("Enter radius, 0 for last: ");
    scanf("%d", &radius);
    printf("Circle curve length: %f.\n", 2.0 * k_PI * radius);
    printf("Circle area: %f.\n", k_PI * radius * radius);
    printf("Sphere volume: %f.\n", 4.0 / 3.0 * k_PI * radius * radius * radius);
  } while (radius != 0);
 
  return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <math.h>
 
float Distance1(float x1, float y1, float x2, float y2) {
  return sqrt(pow(x1 + x2, 2.) + pow(y1 + y2, 2.));
}
 
float Distance2(float x1, float y1, float x2, float y2) {
  return sqrt((x1 + x2) * (x1 + x2) + (y1 + y2) * (y1 + y2));
}
 
clock_t TestDistanceFunction(float (*function)(float, float, float, float),
                             size_t iterations) {
  size_t i;
  clock_t start_time = clock();
  for (i = 0; i < iterations; ++i) {
    float result = function((rand() % 10000) / 100., (rand() % 10000) / 100.,
                            (rand() % 10000) / 100., (rand() % 10000) / 100.);
    result += 1.;
  }
  return clock() - start_time;
}
 
int main(int argc, char *argv[]) {
  srand(time(NULL));
  size_t operation_count = 1500000;
 
  printf("%f\n", TestDistanceFunction(Distance1, operation_count) /
                 (float)CLOCKS_PER_SEC);
  printf("%f\n", TestDistanceFunction(Distance2, operation_count) /
                 (float)CLOCKS_PER_SEC);
 
  return 0;
}