}
    if ((f1 = fopen(argv[1], "r")) == NULL)
    {
        printf("Could not open file %s for input\n", argv[1]);    
        exit(EXIT_FAILURE);
    }
    if ((f2 = fopen(argv[2], "r")) == NULL)
    {
        printf("Could not open file %s for input\n", argv[2]);    
        exit(EXIT_FAILURE);
    }
    ch1 = getc(f1);
    ch2 = getc(f2);
    
    while (ch1 != EOF || ch2 != EOF)
    {
        while (ch1 != EOF && ch1 != '\n') /* skipped after EOF reached */
        {
            putchar(ch1);
            ch1 = getc(f1);
        }
        if (ch1 != EOF)
        {
            if (ch2 == EOF)
                putchar('\n');
            else
                putchar(' ');
            ch1 = getc(f1);
        }
        while (ch2 != EOF && ch2 != '\n') /* skipped after EOF reached */
        {
            putchar(ch2);
            ch2 = getc(f2);
        }
 
        if (ch2 != EOF)
        {
            putchar('\n');
            ch2 = getc(f2);
        }
    }
        
    if (fclose(f1) != 0)
        printf("Could not close file %s\n", argv[1]);    
    if (fclose(f2) != 0)
        printf("Could not close file %s\n", argv[2]);    
        
    return 0;
}
 
PE 13-9
 
/* Programming Exercise 13-9 */
/* to simplify accounting, store one number and word per line */
 
#include <stdio.h>
#include <stdlib.h>
#define MAX 40
 
int main(void)
{
     FILE *fp;
     char words[MAX];
     int wordct = 0;
 
     if ((fp = fopen("wordy", "a+")) == NULL)
     {
          fprintf(stderr,"Can't open \"words\" file.\n");
          exit(1);
     }
     /* determine current number of entries */
     rewind(fp);
     while (fgets(words, MAX - 1, fp) != NULL)
         wordct++;
     rewind(fp);
     
     puts("Enter words to add to the file. Enter one word per line, and ");
     puts("press the Enter key at the beginning of a line to terminate.");
     while (gets(words) != NULL  && words[0] != '\0')
          fprintf(fp, "%d: %s\n", ++wordct, words);
     puts("File contents:");
     rewind(fp);           /* go back to beginning of file */
     while (fgets(words, MAX - 1, fp) != NULL)
          fputs(words, stdout);
     if (fclose(fp) != 0)
          fprintf(stderr,"Error closing file\n");
 
     return 0;
}
 
PE 13-11
 
/* Programming Exercise 13-11 */
 
#include <stdio.h>
#include <stdlib.h>
#include <console.h>    /* Macintosh adjustment */
 
#define SLEN 256
const char *errmesg[] = {"Usage: %s string filename]\n",
                         "Can't open file %s\n" };
            
int main(int argc, char *argv[])
{
    FILE *fp;
    char line[SLEN];
 
    argc = ccommand(&argv);   /* Macintosh adjustment */  
    if (argc != 3)
    {
        fprintf(stderr, errmesg[0], argv[0]);
        exit(EXIT_FAILURE);
    }
 
    if ((fp = fopen(argv[2], "r")) == NULL)
    {
        fprintf(stderr, errmesg[1], argv[2]);
        exit(EXIT_FAILURE);
    }
    
    while (fgets(line, SLEN - 1, fp) != NULL)
    {
        if (strstr(line, argv[1]) != NULL)
            fputs(line, stdout);
    }
        
    fclose(fp);
 
    return 0;
}
 
PE 13-12
 
Data for program:
0 0 9 0 0 0 0 0 0 0 0 0 5 8 9 9 8 5 2 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 9 0 0 0 0 0 0 0 5 8 9 9 8 5 5 2 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 5 8 1 9 8 5 4 5 2 0 0 0 0 0 0 0 0 0
0 0 0 0 9 0 0 0 0 0 0 0 5 8 9 9 8 5 0 4 5 2 0 0 0 0 0 0 0 0
0 0 9 0 0 0 0 0 0 0 0 0 5 8 9 9 8 5 0 0 4 5 2 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 5 8 9 1 8 5 0 0 0 4 5 2 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 5 8 9 9 8 5 0 0 0 0 4 5 2 0 0 0 0 0
5 5 5 5 5 5 5 5 5 5 5 5 5 8 9 9 8 5 5 5 5 5 5 5 5 5 5 5 5 5
8 8 8 8 8 8 8 8 8 8 8 8 5 8 9 9 8 5 8 8 8 8 8 8 8 8 8 8 8 8
9 9 9 9 0 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 3 9 9 9 9 9 9 9
8 8 8 8 8 8 8 8 8 8 8 8 5 8 9 9 8 5 8 8 8 8 8 8 8 8 8 8 8 8
5 5 5 5 5 5 5 5 5 5 5 5 5 8 9 9 8 5 5 5 5 5 5 5 5 5 5 5 5 5
0 0 0 0 0 0 0 0 0 0 0 0 5 8 9 9 8 5 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 5 8 9 9 8 5 0 0 0 0 6 6 0 0 0 0 0 0
0 0 0 0 2 2 0 0 0 0 0 0 5 8 9 9 8 5 0 0 5 6 0 0 6 5 0 0 0 0
0 0 0 0 3 3 0 0 0 0 0 0 5 8 9 9 8 5 0 5 6 1 1 1 1 6 5 0 0 0
0 0 0 0 4 4 0 0 0 0 0 0 5 8 9 9 8 5 0 0 5 6 0 0 6 5 0 0 0 0
0 0 0 0 5 5 0 0 0 0 0 0 5 8 9 9 8 5 0 0 0 0 6 6 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 5 8 9 9 8 5 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 5 8 9 9 8 5 0 0 0 0 0 0 0 0 0 0 0 0
 
/* Programming Exercise 13-12 */
#include <stdio.h>
#include <stdlib.h>
 
#define ROWS    20
#define COLS    30
#define LEVELS    10
const char trans[LEVELS + 1] = " .':~*=&%@";
 
void MakePic(int data[][COLS], char pic[][COLS], int rows);
void init(char arr[][COLS], char ch);
 
int main()
{
    int row, col;
    int picIn[ROWS][COLS];
    char picOut[ROWS][COLS];
    char fileName[40];
    FILE * infile;
    
    init(picOut, 'S');
    
    printf("Enter name of file: ");
    scanf("%s", fileName);
    if ((infile = fopen(fileName, "r")) == NULL)
    {
        fprintf(stderr, "Could not open data file.\n");
        exit(EXIT_FAILURE);
    }
    
    for (row = 0; row < ROWS; row++)
        for (col = 0; col < COLS; col++)
            fscanf(infile, "%d",  &picIn[row][col]);
    if (ferror(infile))
    {
        fprintf(stderr, "Error getting data from file.\n");
        exit(EXIT_FAILURE);
    }
    MakePic(picIn, picOut, ROWS);
 
    for (row = 0; row < ROWS; row++)
    {
        for (col = 0; col < COLS; col++)
            putchar(picOut[row][col]);
        putchar('\n');
    }
    return 0;
}
 
void init(char arr[][COLS], char ch)
{
    int r, c;
    for (r = 0; r < ROWS; r++)
        for (c = 0; c < COLS; c++)
            arr[r][c] = ch;
}
 
void MakePic(int data[][COLS], char pic[][COLS], int rows)
{
    int row, col;
    for (row = 0; row < rows; row++)
        for (col = 0; col < COLS; col++)
            pic[row][col] = trans[data[row][col]];
}
 
Chapter 14
 
PE 14-1
 
/* pe14-1.c  */
#include <stdio.h>
#include <string.h>
#include <ctype.h>
 
struct month {
    char name[10];
    char abbrev[4];
    int days;
    int monumb;
};
 
const struct month months[12] = {
    {"January", "Jan", 31, 1},
    {"February", "Feb", 28, 2},
    {"March", "Mar", 31, 3},
    {"April", "Apr", 30, 4},
    {"May", "May", 31, 5},
    {"June", "Jun", 30, 6},
    {"July", "Jul", 31, 7},
    {"August", "Aug", 31, 8},
    {"September", "Sep", 30, 9},
    {"October", "Oct", 31, 10},
    {"November", "Nov", 30, 11},
    {"December", "Dec", 31, 12}
};
 
int days(char * m);
int main(void)
{
    char input[20];
    int daytotal;
 
    printf("Enter the name of a month: ");
    while (gets(input) != NULL && input[0] != '\0')
    {
        daytotal = days(input);
        if (daytotal > 0)
            printf("There are %d days through %s.\n", daytotal, input);
        else
            printf("%s is not valid input.\n", input);
        printf("Next month (empty line to quit): ");
    }
    puts("bye");
    
    return 0;
}
 
int days(char * m)
{
    int total = 0;
    int mon_num = 0;
    int i;
    if (m[0] == '\0')
        total = -1;
    else
    {
        m[0] = toupper(m[0]);
        for (i = 1; m[i] != '\0'; i++)
            m[i] = tolower(m[i]);
        for (i = 0; i < 12; i++)
            if (strcmp(m, months[i].name) == 0)
            {
                mon_num = months[i].monumb;
                break;
            }
        if (mon_num == 0)
            total = -1;
        else
            for (i = 0; i < mon_num; i++)
                total +=months[i].days;
    }
    return total;
}
 
PE 14-3
 
/* pe14-3.c */
#include <stdio.h>
#include <string.h>
#define MAXTITL   40
#define MAXAUTL   40
#define MAXBKS   100            /* maximum number of books  */
struct book {                   /* set up book template     */
    char title[MAXTITL];
    char author[MAXAUTL];
    float value;
};
 
void sortt(struct book * pb[], int n);
void sortv(struct book * pb[], int n);
 
int main(void)
{
     struct book library[MAXBKS]; /* array of book structures */
     struct book * pbk[MAXBKS];   /* pointers for sorting     */
     int count = 0;
     int index;
 
     printf("Please enter the book title.\n");
     printf("Press [enter] at the start of a line to stop.\n");
     while (count < MAXBKS && gets(library[count].title) != NULL
                         && library[count].title[0] != '\0')
     {
          printf("Now enter the author.\n");
          gets(library[count].author);
          printf("Now enter the value.\n");
          scanf("%f", &library[count].value);
          pbk[count] = &library[count];
          count++;
          while (getchar() != '\n')
               continue;                /* clear input line */
          if (count < MAXBKS)
          printf("Enter the next title.\n");
     }
     printf("Here is the list of your books:\n");
     for (index = 0; index < count; index++)
         printf("%s by %s: $%.2f\n", library[index].title,
          library[index].author, library[index].value);
          
     printf("Here is the list of your books sorted by title:\n");
     sortt(pbk, count);
     for (index = 0; index < count; index++)
         printf("%s by %s: $%.2f\n", pbk[index]->title,
          pbk[index]->author, pbk[index]->value);
     sortv(pbk, count);
     printf("Here is the list of your books sorted by value:\n");
     for (index = 0; index < count; index++)
         printf("%s by %s: $%.2f\n", pbk[index]->title,
          pbk[index]->author, pbk[index]->value);
 
     return 0;
}
 
void sortt(struct book * pb[], int n)
{
   int top, search;
   struct book * temp;
 
   for (top = 0; top < n -1; top++)
       for (search = top + 1; search < n; search++)
            if (strcmp(pb[search]->title, pb[top]->title) < 0)
            {
                 temp = pb[search];
                 pb[search] = pb[top];
                 pb[top] = temp;
            }
}
 
void sortv(struct book * pb[], int n)
{
   int top, search;
   struct book * temp;
 
   for (top = 0; top < n -1; top++)
       for (search = top + 1; search < n; search++)
            if (pb[search]->value < pb[top]->value)
            {
                 temp = pb[search];
                 pb[search] = pb[top];
                 pb[top] = temp;
            }
}
 
PE 14-5
 
    /* pe14-5.c */
#include <stdio.h>
#include <string.h>
#define LEN 14
#define CSIZE 4
#define SCORES 3
struct name {
    char first[LEN];
    char last[LEN];
};
struct student {
    struct name person;
    float scores[SCORES];
    float mean;
};
void get_scores(struct student ar[], int lim);
void find_means(struct student ar[], int lim);
void show_class(const struct student ar[], int lim);
void show_ave(const struct student ar[], int lim); 
 
int main(void)
{
    struct student class[CSIZE] ={
        { "Flip", "Snide"},
        { "Clare", "Voyans"},
        { "Bingo", "Higgs"},
        { "Fawn", "Hunter"}
    };
 
    get_scores(class, CSIZE);
    find_means(class, CSIZE);
    show_class(class, CSIZE);
    show_ave(class, CSIZE);
    return 0;
}
 
void get_scores(struct student ar[], int lim)
{
    int i,j;
    for (i = 0; i < lim; i++)
    {
        printf ("Please enter %d scores for %s %s:\n", SCORES,
            ar[i].person.first, ar[i].person.last);
        for (j = 0; j < SCORES; j++)
        {
            while (scanf("%f", &ar[i].scores[j]) != 1)
            {
                scanf("%*s");
                puts("Please use numeric input.");
            }
        }
    }
}
 
void find_means(struct student ar[], int lim)
{
    int i, j;
    float sum;
    
    for (i = 0; i < lim; i++)
    {
        for (sum = 0, j = 0; j < SCORES; j++)
            sum += ar[i].scores[j];
        ar[i].mean = sum / SCORES;
    }
}
 
void show_class(const struct student ar[], int lim)
{
    int i, j;
    char wholename[2*LEN];
    
    for (i = 0; i < lim; i++)
    {
        strcpy(wholename, ar[i].person.first);
         strcat(wholename, " ");
         strcat(wholename, ar[i].person.last);
          printf("%27s: ", wholename);
          for (j = 0; j < SCORES; j++)
            printf("%6.1f ", ar[i].scores[j]);
        printf(" Average = %5.2f\n", ar[i].mean);
    }
}
 
void show_ave (const struct student ar[], int lim)
{
    int i, j;
    float total;
 
    printf("\n%27s: ", "QUIZ AVERAGES");
    for (j = 0; j < SCORES; j++)
    {
        for (total = 0, i = 0; i < lim; i++)
            total += ar[i].scores[j];
        printf("%6.2f ", total / lim);
    }
    putchar('\n');
}
 
PE 14-7
 
/* pe14-7.c */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAXTITL     40
#define MAXAUTL     40
#define MAXBKS      10         /* maximum number of books */
#define CONTINUE    0
#define DONE        1
#define YES         1
#define NO          0
struct book {                  /* set up book template    */
    char title[MAXTITL];
    char author[MAXAUTL];
    float value;
    int delete;
};
 
int getlet(const char * s);
int getbook(struct book * pb);
void update(struct book * item);
 
int main(void)
{
     struct book library[MAXBKS]; /* array of structures     */
     int count = 0;
     int deleted = 0;
     int index, filecount, open;
     FILE * pbooks;
     int size = sizeof (struct book);
 
     if ((pbooks = fopen("book.dat", "r")) != NULL)
     {
         while (count < MAXBKS &&  fread(&library[count], size,
                     1, pbooks) == 1)
         {
             if (count == 0)
                 puts("Current contents of book.dat:");
             printf("%s by %s: $%.2f\n",library[count].title,
                 library[count].author, library[count].value);
             printf("Do you wish to change or delete this entry?<y/n> ");
             if (getlet("yn") == 'y')
             {
                 printf("Enter c to change, d to delete entry: ");
                 if (getlet("cd") == 'd')
                 {
                     library[count].delete = YES;
                     deleted++;
                     puts("Entry marked for deletion.");
                 }
                 else
                     update(&library[count]);
             }
             count++;
         }
         fclose(pbooks);
     }
     filecount = count - deleted;
     if (count == MAXBKS)
     {
         fputs("The book.dat file is full.", stderr);
         exit(2);
     }
     puts("Please add new book titles.");
     puts("Press [enter] at the start of a line to stop.");
     open = 0;
     while (filecount < MAXBKS)
     {
        if (filecount < count)
        {
            while (library[open].delete == NO)
                open++;
            if (getbook(&library[open]) == DONE)
                break;
        }
        else if (getbook(&library[filecount]) == DONE)