שפת C/מערכים/תרגילים

#include <stdio.h>
 
 
int main()
{
  char array[5] = {'1', '3', '5', '7', '9'};
  int i;
 
  for(i = 0; i < 5; ++i)
    printf("%c \n", array[i]);  
 
  return 0;
}

#include <stdio.h>
 
 
int main()
{
  int array[5];
  int i;
 
  for(i = 0; i < 5; ++i)
  {
    int input;
 
    printf("Please enter element %d: ", i);
 
    scanf("%d", &input);
    array[i] = input;
  }
 
  for(i = 0; i < 4; ++i)
    printf("%d ", array[i]);  
 
  return 0;
}

#include <stdio.h>
 
 
int main()
{
  int array[15] = {1, 3, 5, 7, 9, 1, 3, 5, 8, 9, 1, 3, 5, 8, 9};
  int hist[10];
  int i;
 
  for(i = 0; i < 10; ++i)
    hist[i] = 0;
 
  for(i = 0; i < 15; ++i)
    ++hist[array[i]];
 
  for(i = 0; i < 10; ++i)
    printf("%d appears %d times\n", i, hist[i]);
 
  return 0;
}

#include <stdio.h>
 
 
int main()
{
  char matrix[4][3]=
  { {'1','2','3'} , {'4','5','6'} , {'7','8','9'} , {'a','b','c'}};
  int i, j;
 
  for(i = 0; i < 4; ++i)
  {
    for(j = 0; j < 3; ++j)
      printf("%c ", matrix[i][j]);  
 
    printf("\n");
  }  
 
  return 0;
}

#include <stdio.h>
 
 
int main()
{
  int matrix[4][3];
  int i, j;
 
  for(i = 0; i < 4; ++i)
    for(j = 0; j < 3; ++j)
  {
    int input;
 
    printf("Please enter element (%d, %d): ", i, j);
 
    scanf("%d", &input);
    matrix[i][j] = input;
  }
 
  for(i = 0; i < 4; ++i)
  {
    for(j = 0; j < 3; ++j)
      printf("%d ", matrix[i][j]);  
 
    printf("\n");
  }  
 
  return 0;
}

#include <stdio.h>
 
 
int main()
{
  char matrix[4][3]=
  { {'1','2','3'} , {'4','5','6'} , {'7','8','9'} , {'a','b','c'}};
 
  unsigned int row, column;
 
  printf("Please enter a row and column: ");
  scanf("%d %d", &row, &column);
 
  /* We need to decrease these variables, since C arrays are 0-based, not 1-based. */
  --row;
  --column;
 
  /* Always check for access violation! */
  if(row >= 4 || column >= 3)
  {
    printf("Illegal choice!");
 
    return -1;
  }
 
  printf("%c\n", matrix[row][column]);
 
  return 0;
}

#include <stdio.h>
 
 
int main()
{
  int matrix[4][3]=
    { {1,2,3} , {4,5,6} , {7,8,9} , {10, 11, 12}};
 
  int i, j, sum;
 
  for(i = 0; i < 4; ++i)
  {
    sum = 0;
 
    for(j = 0; j < 3; ++j)
      sum += matrix[i][j];
 
    printf("The sum of row %d is %d\n", i, sum);
  }
 
  for(j = 0; j < 3; ++j)
  {
    sum = 0;
 
    for(i = 0; i < 4; ++i)
      sum += matrix[i][j];
 
    printf("The sum of column %d is %d\n", j, sum);
  }
 
   return 0;
}

#include <stdio.h>
 
#define UP 0
#define RIGHT 1
#define DOWN 2
#define LEFT 3
 
int main()
{
  int dir; //direction
  int x,y; //posiotion
  int u,r,d,l; //limits: up, right, down, left
  int count; //just counts the cells that printed
 
  char arr[4][3]=
    { {'1','2','3'} , {'4','5','6'} , {'7','8','9'} , {'a','b','c'}};
 
  //at first, direction set to be right
  dir=RIGHT;
 
  //we start at this corner
  x=0;
  y=0;
 
  //at first, limits are edges of array
  u=1;
  r=3-1;
  d=4-1;
  l=0;
 
  for(count=0;count<3*4;count++)
  {
    printf("%c ", arr[x][y]);
    switch(dir){
    case UP:
      //move to direction
      x--;
      //if we are on the limit: move limit one step to center & change direction
      if(x===u) {
        u++;
        dir=(dir+1)%4;
      }
      break;
    case RIGHT:
      //move to direction
      y++;
      //if we are on the limit: move limit one step to center & change direction
      if(y===r) {
        r--;
        dir=(dir+1)%4;
      }
      break;
    case DOWN:
      //move to direction
      x++;
      //if we are on the limit: move limit one step to center & change direction
      if(x===d) {
        d--;
        dir=(dir+1)%4;
      }
      break;
    case LEFT:
      //move to direction
      y--;
      //if we are on the limit: move limit one step to center & change direction
      if(y===l) {
        l++;
        dir=(dir+1)%4;
      }
      break;
    }
  }
  return 0;
}