C语言程序设计第二版课后习题--第七章

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

int main(int argc, char **argv)
{
    int (*handler[2])(int) = {tolower, toupper};

    int type = strcmp(argv[0], "./lower") == 0 ? 0 : strcmp(argv[0], "./upper") == 0 ? 1 : -1;

    if (type == -1) {
        fprintf(stderr, "Usage: %s [lower|upper]\n", argv[0]);
    } else {
        int c;
        while ((c = getchar()) != EOF)
            putchar(handler[type](c));
    }
}

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➜  ch07 git:(main) ✗ gcc -o lower Exercise7-1.c 
➜  ch07 git:(main) ✗ ./lower               
This
this
IYUSDbusaIs
iyusdbusais
➜  ch07 git:(main) ✗ gcc -o other Exercise7-1.c
➜  ch07 git:(main) ✗ ./other 
Usage: ./other [lower|upper]

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void minprintf(char *fmt, ...)
{
    va_list ap; /* points to each unnamed arg in turn */
    char *p, *sval;
    int ival;
    double dval;
    va_start(ap, fmt); /* make ap point to 1st unnamed arg */
    for (p = fmt; *p; p++)
    {
        if (*p != '%')
        {
            putchar(*p);
            continue;
        }
        switch (*++p)
        {
        case 'd':
            ival = va_arg(ap, int);
            printf("%d", ival);
            break;
        case 'f':
            dval = va_arg(ap, double);
            printf("%f", dval);
            break;
        case 's':
            for (sval = va_arg(ap, char *); *sval; sval++)
                putchar(*sval);
            break;
        case 'c':   // 字符
            ival = va_arg(ap, int);
            printf("%c", ival);
            break;
        case 'x':   // 十六进制
            ival = va_arg(ap, int);
            printf("%x", ival);
            break;
        case 'o':   // 八进制
            ival = va_arg(ap, int);
            printf("%o", ival);
            break;
        case '%':   // 百分号
            putchar('%');
            break;
        case 'g':   // 浮点数
            dval = va_arg(ap, double);
            printf("%g", dval);
            break;
        default:
            putchar(*p);
            break;
        }
    }
    va_end(ap); /* clean up when done */
}

int main()
{
    minprintf("int: %d, float: %g, string: %s\n", 10, 3.14, "hello");
    minprintf("char: %c, hex: %x, oct: %o, double: %g, percent: %%\n", 'a', 255, 255, 3.1415926);
    return 0;
}

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int: 10, float: 3.14, string: hello
char: a, hex: ff, oct: 377, double: 3.14159, percent: %

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#include <stdio.h>
#include <stdarg.h>
#include <ctype.h>

void minscanf(char *fmt, ...)
{
    va_list ap;
    char *p, *sval;
    int *ival;
    float *dval;
    unsigned *uval;
    int c;

    va_start(ap, fmt);
    for (p = fmt; *p; p++)
    {
        while (*p != '%')
            p++;
        switch (*++p)
        {
        case 'd':
            ival = va_arg(ap, int *);
            scanf("%d", ival);
            break;
        case 'f':
            dval = va_arg(ap, float *);
            scanf("%f", dval);
            break;
        case 's':
            sval = va_arg(ap, char *);
            scanf("%s", sval);
            break;
        case 'c':
            ival = va_arg(ap, int *);
            *ival = getchar();
            break;
        default:
            break;
        }
    }
    va_end(ap);
}

int main()
{
    int i;
    float f;
    char s[100];
    char c;

    printf("Enter an integer: ");
    minscanf("%d", &i);
    printf("i = %d\n", i);
    printf("Enter a float: ");
    minscanf("%f", &f);
    printf("f = %f\n", f);
    printf("Enter a string: ");
    minscanf("%s", s);
    printf("s = %s\n", s);
    getchar(); // clear the input buffer
    printf("Enter a character: ");
    minscanf("%c", &c);
    printf("c = %c\n", c);
}

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Enter an integer: 1
i = 1
Enter a float: 3.14
f = 3.140000
Enter a string: ioio
s = ioio
Enter a character: a
c = a

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int main()
{
    int type;
    double op2;
    char s[MAXOP];
    printf("Please input expression:\n");
    while ((type = getop(s)) != EOF)
    {
        switch (type)
        {
        case NUMBER:
            push(atof(s));
            break;
        ...
        }
    }
}

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int main()
{
    int type;
    double op2;
    char s[MAXOP];
    printf("Please input expression:\n");
    while ((type = getop(s)) != EOF)
    {
        switch (type)
        {
        case NUMBER:
            int val;
            scanf("%f", &val);
            push(val);
            break;
        ...
        }
    }
}

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void filecmp(FILE *fp1, FILE *fp2)
{
    char *line1 = malloc(MAXLINE), *line2 = malloc(MAXLINE);
    int lineno = 1;
    while (fgets(line1, 100, fp1) != NULL && fgets(line2, 100, fp2) != NULL)
    {
        if (strcmp(line1, line2) != 0)
        {
            printf("difference in line %d\n", lineno);
            printf("line1: %s\n", line1);
            printf("line2: %s\n", line2);
            return;
        }
        lineno++;
    }
    if (feof(fp1) && feof(fp2))
        printf("files are identical\n");
    else if (feof(fp1))
        printf("file2 has extra lines\n");
    else
        printf("file1 has extra lines\n");
}

int main(int argc, char *argv[])
{
    FILE *fp1, *fp2;
    char *prog = argv[0];       /* program name for errors */
    if (argc == 1 || argc == 2) /* no args; copy standard input */
        fprintf(stderr, "Usage: %s file1 file2\n", prog);
    else
    {
        if ((fp1 = fopen(*++argv, "r")) == NULL)
        {
            fprintf(stderr, "%s: can't open %s\n",
                    prog, *argv);
            exit(1);
        }
        if ((fp2 = fopen(*++argv, "r")) == NULL)
        {
            fprintf(stderr, "%s: can't open %s\n",
                    prog, *argv);
            exit(1);
        }
        filecmp(fp1, fp2);
    }
    fclose(fp1);
    fclose(fp2);
    exit(0);
}

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➜  ch07 git:(main) ✗ ./Exercise7-6 Exercise7-6.c Exercise7-5.c
difference in line 5
line1: #define MAXLINE 1000

line2: void filecopy(FILE *ifp, FILE *ofp)

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

#define MAXLINE 1024
#define LINES_PER_PAGE 3

void print_file(char *file_name)
{
    FILE *f;
    int page_number = 1;
    int line_count;
    int c;
    int new_page = 1;
    assert(file_name != NULL);
    char *line = malloc(MAXLINE);
    if ((f = fopen(file_name, "r")) != NULL)
    {
        while (fgets(line, MAXLINE, f) != NULL)
        {
            if (new_page)
            {
                printf("[%s] page %d starts\n", file_name, page_number);
                new_page = 0;
                line_count = 1;
            }
            if (!feof(f) && ++line_count > LINES_PER_PAGE)
            {
                /* print out the footer */
                printf("[%s] page %d ends\n", file_name, page_number);
                /* skip another line so we can see it on screen */
                putchar('\n');
                new_page = 1;
                page_number++;
            }
            else
            {
                fputs(line, stdout);
            }
        }
        /* skip another line so we can see it on screen */
        putchar('\n');
        fclose(f);
    }
}
int main(int argc, char *argv[])
{
    int i;
    if (argc < 2)
    {
        fputs("no files specified\n", stderr);
        return EXIT_FAILURE;
    }
    for (i = 1; i < argc; i++)
        print_file(argv[i]);
    
    return EXIT_SUCCESS;
}

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➜  ch07 git:(main) ✗ ./Exercise7-8 test.txt
[test.txt] page 1 starts
It’s quite a good summary, but it would have even better when taking into account the importance of the number of requested rows, expected by the Cassandra client.
1) “To perform the country index lookup, every node is queried, looks up the 'UK' partition and then looks up each user_accounts partition found. ”
[test.txt] page 1 ends

[test.txt] page 2 starts
2) “This leads to the conclusion that the best use case for Cassandra's secondary indexes is when p is approximately n i.e. the number of partitions is about equal to the number of nodes.”
What a narrow best use case ! Hopefully, there are other use cases where seconday index are fine (that is, for low-cardinality sets), or even finer (according to the number of resulting rows requested vs the cardinality of indexed values).

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# define isupper(c) __isctype((c), _ISupper)

# define __isctype(c, type) \
  ((*__ctype_b_loc ())[(int) (c)] & (unsigned short int) type)