我将如何修复此表上的对齐方式？

Question

我已经用 C 编写了这个程序，它读取一个文件并将其打印到一个与垂直条对齐的表格中，包括标题和足迹。该文件始终有 3 列，但行数不同。这些列的字符数量会有所不同。我遇到的问题是，我读入的第一个文件完全对齐，但是当我读入其他所有列中尺寸增加的文件时，它没有对齐。有没有办法让它自动对齐，还是我每次都必须手动执行？

代码：

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

// constant to store the maximum size of the records that can be read from the file

enum
{
    // update MAX_SIZE to if the number of rows is more than 1000
    MAX_SIZE = 1024
};

// structure to store a record from the file
typedef struct
{
    char define[20];
    char octal[26];
    char description[1000];
} Record;

// string to store the header of the table
char header1[20], header2[20], header3[20];

// function to read the file and return the maximum length of the descriptions read from the file
int readFile(Record rec[], int *size)
{
    // open a file for input
    FILE *fp = fopen("input2.txt", "r");

    // check if the file opened successfully
    if (fp == NULL)
    {
        printf("File could not be opened!");
        exit(1);
    }

    int i = 0;
    int maxLength=0;
    // read the file
    // first we read the header of each column from the file
    fscanf(fp, "%s %s %s\n", header1, header2, header3);

    // now we read each record from the file
    while (fscanf(fp, "%19s ", rec[i].define) == 1) 
    {
        fscanf(fp, "%10s '%[^']'", rec[i].octal, rec[i].description);

        // find the length of the description and update the 'maxLength'
        if (strlen(rec[i].description) > maxLength) 
        {
            maxLength = strlen(rec[i].description);
        }

        // increment the value of i
        i++;
    }
    
    // close the input file
    fclose(fp);

    // update the number of records read from the file
    *size = i;

    return maxLength;
}

void printTable(Record rec[], int size, int WIDTH)
{
    char p='|';
    // print the header of the table
    for (int i = 0; i < 22 + WIDTH; i++)
        printf("-");

    printf("\n| %-7s %c %5s %c %-*s %c\n", header1, p, header2, p, WIDTH, header3,p);

    for (int i = 0; i < 22 + WIDTH; i++)
        printf("-");

    printf("\n");

    // print the table data
    for (int i = 0; i < size; i++)
        printf("| %-7s | %5s | %-*s |\n", rec[i].define, rec[i].octal, WIDTH, rec[i].description);

    // print the footer
    for (int i = 0; i < 22 + WIDTH; i++)
        printf("-");

    printf("\n");
}

// driver function
int main()
{
    // create an array of recors of MAX_SIZE
    Record recs[MAX_SIZE];
    // initialize size of recs to zero
    int size = 0;

    // call readFile() function to read data from the file and update the size of recs
    int WIDTH = readFile(recs, &size);
    // call printTable() function to print the table in a well-formatted manner
    printTable(recs, size, WIDTH);

    return 0;
}

文件：

#define octal description
O_APPEND 02000 'The file is opened in append mode.'
O_ASYNC 020000 'Enable signal-driven I/O.'
O_CLOEXEC 02000000 'Enable the close-on-exec flag for the new file descriptor.'
O_CREAT 0100 'If pathname does not exist, create it as a regular file.'
O_DIRECT 040000 'Try to minimize cache effects of the I/O to and from this file.'
O_DIRECTORY 0200000 'If pathname is not a directory, cause the open to fail.'
O_DSYNC 010000 'Write operations will complete according to the requirements of synchronized I/O data integrity completion.'
O_EXCL 0200 'Ensure that this call creates the file.'
O_LARGEFILE 0 'Allow files whose sizes cannot be represented in an off_t to be opened.'
O_NOATIME 01000000 'Do not update the file last access time (st_atime in the inode) when the file is read(2).'
O_NOCTTY 0400 'If pathname refers to a terminal device it will not become the processs controlling terminal.'
O_NOFOLLOW 0400000 'If pathname is a symbolic link, then the open fails, with the error ELOOP.'
O_NONBLOCK 04000 'When possible, the file is opened in nonblocking mode.'
O_PATH 010000000 'Obtain a file descriptor that can be used perform operations that act purely at the file descriptor level.'
O_SYNC 04010000 'Write operations will complete according to the requirements of synchronized I/O file integrity completion.'
O_TMPFILE 020200000 'Create an unnamed temporary regular file.'
O_TRUNC 01000 'If the file already exists and is a regular file it will be truncated to length 0.'

当前正在打印的内容：

---------------------------------------------------------------------------------------------------------------------------------
| #define | octal | description                                                                                                 |
---------------------------------------------------------------------------------------------------------------------------------
| O_APPEND | 02000 | The file is opened in append mode.                                                                          |
| O_ASYNC | 020000 | Enable signal-driven I/O.                                                                                   |
| O_CLOEXEC | 02000000 | Enable the close-on-exec flag for the new file descriptor.                                                  |
| O_CREAT |  0100 | If pathname does not exist, create it as a regular file.                                                    |
| O_DIRECT | 040000 | Try to minimize cache effects of the I/O to and from this file.                                             |
| O_DIRECTORY | 0200000 | If pathname is not a directory, cause the open to fail.                                                     |
| O_DSYNC | 010000 | Write operations will complete according to the requirements of synchronized I/O data integrity completion. |
| O_EXCL  |  0200 | Ensure that this call creates the file.                                                                     |
| O_LARGEFILE |     0 | Allow files whose sizes cannot be represented in an off_t to be opened.                                     |
| O_NOATIME | 01000000 | Do not update the file last access time (st_atime in the inode) when the file is read(2).                   |
| O_NOCTTY |  0400 | If pathname refers to a terminal device it will not become the processs controlling terminal.               |
| O_NOFOLLOW | 0400000 | If pathname is a symbolic link, then the open fails, with the error ELOOP.                                  |
| O_NONBLOCK | 04000 | When possible, the file is opened in nonblocking mode.                                                      |
| O_PATH  | 010000000 | Obtain a file descriptor that can be used perform operations that act purely at the file descriptor level.  |
| O_SYNC  | 04010000 | Write operations will complete according to the requirements of synchronized I/O file integrity completion. |
| O_TMPFILE | 020200000 | Create an unnamed temporary regular file.                                                                   |
| O_TRUNC | 01000 | If the file already exists and is a regular file it will be truncated to length 0.                          |
---------------------------------------------------------------------------------------------------------------------------------

它应该是什么样子：

-----------------------------------------------------------------------------------------------------------------------------------------
| #define     |     octal | description                                                                                                 |
-----------------------------------------------------------------------------------------------------------------------------------------
| O_APPEND    |     02000 | The file is opened in append mode.                                                                          |
| O_ASYNC     |    020000 | Enable signal-driven I/O.                                                                                   |
| O_CLOEXEC   |  02000000 | Enable the close-on-exec flag for the new file descriptor.                                                  |
| O_CREAT     |      0100 | If pathname does not exist, create it as a regular file.                                                    |
| O_DIRECT    |    040000 | Try to minimize cache effects of the I/O to and from this file.                                             |
| O_DIRECTORY |   0200000 | If pathname is not a directory, cause the open to fail.                                                     |
| O_DSYNC     |    010000 | Write operations will complete according to the requirements of synchronized I/O data integrity completion. |
| O_EXCL      |      0200 | Ensure that this call creates the file.                                                                     |
| O_LARGEFILE |         0 | Allow files whose sizes cannot be represented in an off_t to be opened.                                     |
| O_NOATIME   |  01000000 | Do not update the file last access time (st_atime in the inode) when the file is read(2).                   |
| O_NOCTTY    |      0400 | If pathname refers to a terminal device it will not become the processs controlling terminal.               |
| O_NOFOLLOW  |   0400000 | If pathname is a symbolic link, then the open fails, with the error ELOOP.                                  |
| O_NONBLOCK  |     04000 | When possible, the file is opened in nonblocking mode.                                                      |
| O_PATH      | 010000000 | Obtain a file descriptor that can be used perform operations that act purely at the file descriptor level.  |
| O_SYNC      |  04010000 | Write operations will complete according to the requirements of synchronized I/O file integrity completion. |
| O_TMPFILE   | 020200000 | Create an unnamed temporary regular file.                                                                   |
| O_TRUNC     |     01000 | If the file already exists and is a regular file it will be truncated to length 0.                          |
-----------------------------------------------------------------------------------------------------------------------------------------

Answer 1

考虑一个实现相同目标的人为示例。

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

struct ContrivedData {
    char a[100];
    char b[100];
    char c[100];
};

int main(void) {
    struct ContrivedData cd1 = {"Hello", "world", "!"};
    struct ContrivedData cd2 = {"foo", "bar", "baz"};
    struct ContrivedData cd[2];

    cd[0] = cd1;
    cd[1] = cd2;

    int cd_len = sizeof(cd) / sizeof(*cd);
    
    int max_a_len = 0;
    int max_b_len = 0;
    int max_c_len = 0;

    for (int i = 0; i < cd_len; i++) {
        int a_len = strlen(cd[i].a);
        if (a_len > max_a_len) {
            max_a_len = a_len;
        }

        int b_len = strlen(cd[i].b);
        if (b_len > max_b_len) {
            max_b_len = b_len;
        }

        int c_len = strlen(cd[i].c);
        if (c_len > max_c_len) {
            max_c_len = c_len;
        }
    }

    for (int i = 0; i < cd_len; i++) {
        printf("%-*s | %-*s | %-*s\n", 
               max_a_len, cd[i].a, 
               max_b_len, cd[i].b, 
               max_c_len, cd[i].c);
    }

    return 0;
}

在打印数据之前，我遍历数组并计算每个字段的最大宽度。根据数据的类型，您可能需要使用strlen以外的某些功能。

我得到的结果是：

% ./test2
Hello | world | !  
foo   | bar   | baz

如果我稍微改变一下数据，你可以看到它仍然保持对齐。

% ./test2
Hello | world     | !  
foo   | barbarbar | baz

Answer 2

示例函数。

struct a 
{
    char *s ; int x; char *y;
} a[] = {
    {"Hello", 435342435432, "1"},
    {"dfgsfdgdgdfgdf", 5, "1fdsfsdfs"},
    {"Hellodfds", 43534, "sdffs"},
    {"H", 2435432, "1dfdsfdsfsdd"},
    {NULL,}
};


void print(struct a *data)
{
    int widths[3] = {0};
    struct a *wrk;
    size_t len;

    for(wrk = data; wrk -> s; wrk++)
    {
        if((len = strlen(wrk -> s)) > widths[0]) widths[0] = len;
        if((len = strlen(wrk -> y)) > widths[2]) widths[2] = len;
        if((len = snprintf(NULL, 0, "%d", wrk -> x)) > widths[1]) widths[1] = len;
    }
    for(wrk = data; wrk -> s; wrk++)
    {
        printf("| %-*s | %*d | %*s |\n", widths[0], wrk -> s , widths[1], wrk -> x,  widths[2], wrk -> y);
    }
}

输出：

| Hello          | 1550738536 |            1 |
| dfgsfdgdgdfgdf |          5 |    1fdsfsdfs |
| Hellodfds      |      43534 |        sdffs |
| H              |    2435432 | 1dfdsfdsfsdd |