#include <stdio.h>

#define N 7

long power(int, int);
void prn_heading(void);
void prn_tbl_of_powers(int);

int main(void)
{
  prn_heading();
  prn_tbl_of_powers(N);
  return 0;
}

void prn_heading(void)
{
  printf("\n::::: A TABLE OF POWERS :::::\n\n");
}

void prn_tbl_of_powers(int n)
{
  int i, j;

  for (i = 1; i <= n; ++i) {
    for (j = 1; j <= n; ++j)
      if (j == 1)
        printf("%ld", power(i, j));
      else
        printf("%9ld", power(i, j));
      putchar('\n');
  }
}

long power(int m, int n)
{
  int i;
  long product = 1;

  for (i = 1; i <= n; ++i)
    product *= m;
  return product;
}

#include <stdio.h>

int main(void)
{
  int n = 3, sum, compute_sum(int);

  printf("%d\n", n); /* 3 is printed */
  sum = compute_sum(n);
  printf("%d\n", n); /* 3 is printed */
  printf("%d\n", sum); /* 6 is printed */
  return 0;
}

int compute_sum(int n) /* sum the integers from 1 to n */
{
  int sum = 0;

  for ( ; n > 0; --n) /* stored value of n is changed */
    sum += n;
  return sum;
}

#include "pgm.h"

int main(void)
{
  char ans;
  int i, n = N;

  printf("%s",
    "This program does not do very much.\n"
    "Do you want more information? ");
  scanf(" %c", &ans);
  if (ans == 'y' || ans == 'Y')
    wrt_info("pgm");
  for (i = 0; i < n; ++i)
    fct1(i);
  printf("Bye!\n");
  return 0;
}

#include "pgm.h"

void fct1(int n)
{
  int i;

  printf("Hello from fct1()\n");
  for (i = 0; i < n; ++i)
    fct2();
}

void fct2(void)
{
  printf("Hello from fct2()\n");
}

#include "pgm.h"

void wrt_info(char *pgm_name)
{
  printf("Usage: %s\n\n", pgm_name);
  printf("%s\n",
    "This program illustrates how one can write a program\n"
    "in more than one file. In this example, we have a\n"
    "single .h file that gets included at the top of our\n"
    "three .c files. Thus the .h file acts as the \"glue\"\n"
    "that binds the program together.\n"
    "\n"
    "Note that the functions fct1() and fct2() when called\n"
    "only say \"hello.\" When writing a serious program, the\n"
    "programmer sometimes does this in a first working\n"
    "version of the code.\n");
}

#include <stdio.h>
#include <stdlib.h>

#define N 3

void fct1(int k);
void fct2(void);
void wrt_info(char *);

CC = gcc
CFLAGS = -Wall
EXEC = a.out
INCLS = 
LIBS = 

OBJS = main.o fct.o wrt.o

$(EXEC): $(OBJS)
@echo "linking ..."
@$(CC) $(CFLAGS) -o $(EXEC) $(OBJS) $(LIBS)

$(OBJS): pgm.h
$(CC) $(CFLAGS) $(INCLS) -c $*.c

relink:
@echo "relinking ..."
@$(CC) $(CFLAGS) -o $(EXEC) $(OBJS) $(LIBS)

#include <stdio.h>

int a = 1, b = 2, c = 3; /* global variables */
int f(void); /* function prototype */

int main(void)
{
  printf("%3d\n", f()); /* 12 is printed */
  printf("%3d%3d%3d\n", a, b, c); /* 4 2 3 is printed */
  return 0;
}

int f(void)
{
  int b, c;   /* b and c are local */
              /* global b, c are masked */
  a = b = c = 4;
  return (a + b + c);
}

#include <stdio.h>

int a = 1, b = 2, c = 3; /* external variables */
int f(void);

int main(void)
{
  printf("%3d\n", f());
  printf("%3d%3d%3d\n", a, b, c);
  return 0;
}

int f(void)
{
  extern int a; /* look for it elsewhere */
  int b, c;
 
  a = b = c = 4;
  return (a + b + c);
}

CC = gcc
CFLAGS = -Wall
EXEC = a.out
INCLS = 
LIBS = 

OBJS = main.o fct.o

$(EXEC): $(OBJS)
@echo "linking ..."
@$(CC) $(CFLAGS) -o $(EXEC) $(OBJS) $(LIBS)

$(OBJS):
$(CC) $(CFLAGS) $(INCLS) -c $*.c

relink:
@echo "relinking ..."
@$(CC) $(CFLAGS) -o $(EXEC) $(OBJS) $(LIBS)

/* Write a line backwards. */

#include <stdio.h>

void wrt_it(void);

int main(void)
{

  printf("Input a line: ");
  wrt_it();
  printf("\n\n");
  return 0;
}

void wrt_it(void)
{
  int c;

  if ((c = getchar()) != '\n')
    wrt_it();
  putchar(c);
}

#include "hanoi.h"

int cnt = 0; /* count of the number of moves */

int main(void)
{
  int n; /* number of disks */

  n = get_n_from_user();
  assert(n > 0);

/*
// Move n disks from tower A to tower C,
// using tower B as an intermediate tower.
*/
  move(n, 'A', 'B', 'C'); /* recursive fct */
  return 0;
}

#include "hanoi.h"

void move(int n, char a, char b, char c)
{
  if (n == 1) {
    ++cnt;
    printf("%5d: %s%d%s%c%s%c.\n", cnt,
    "Move disk ", 1, " from tower ", a, " to tower ", c);
  }
  else {
    move(n - 1, a, c, b);
    ++cnt;
    printf("%5d: %s%d%s%c%s%c.\n", cnt,
    "Move disk ", n, " from tower ", a, " to tower ", c);
    move(n - 1, b, a, c);
  }
}

#include "hanoi.h"

int get_n_from_user(void)
{
  int n;

  printf("%s",
    "---\n"
    "TOWERS OF HANOI:\n"
    "\n"
    "There are three towers: A, B, and C.\n"
    "\n"
    "The disks on tower A must be moved to tower C. Only one\n"
    "disk can be moved at a time, and the order on each tower\n"
    "must be preserved at each step. Any of the towers A, B,\n"
    "or C can be used for intermediate placement of a disk.\n"
    "\n"
    "The problem starts with n disks on Tower A.\n"
    "\n"
    "Input n: ");
  if (scanf("%d", &n) != 1 || n < 1) {
    printf("\nERROR: Positive integer not found - bye!\n\n");
    exit(1);
  }
  printf("\n");
  return n;
}

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>

extern int cnt; /* count of the number of moves */

int get_n_from_user(void);
void move(int n, char a, char b, char c);

CC = cc
CFLAGS =
EXEC = a.out
INCLS = 
LIBS = 

OBJS = main.o get.o move.o

$(EXEC): $(OBJS)
@echo "linking ..."
@$(CC) $(CFLAGS) -o $(EXEC) $(OBJS) $(LIBS)

$(OBJS): hanoi.h
$(CC) $(CFLAGS) $(INCLS) -c $*.c

relink:
@echo "relinking ..."
@$(CC) $(CFLAGS) -o $(EXEC) $(OBJS) $(LIBS)