c - 已经使用另一个定界符时在 C 中定界空白(一次)的简单方法

Question

我有以下代码

while (*ptr != ',') {
    int items_read = sscanf(ptr, "%91[^,]%n", field, &n);
    printf("field = \"%s\"\n", field);
    field[0]='\0';
    if (items_read == 1)
        ptr += n; /* advance the pointer by the number of characters read */
    if ( *ptr != ',' ) {
        break; /* didn't find an expected delimiter, done? */
    }
    ++ptr; /* skip the delimiter */
}

它读取我的字符串并为它在逗号之间找到的每个字符串创建一个新数组，但是我在字符串中间有空格。我有许多要读入的字符串，其中一些字符串在多个区域(在中间位置之后)有空格，我不想考虑那个空格，只是第一个实例。

我知道我可以输入 || ' ' 在 while 行、int 行 和/或第二个 if 行 但我还没有到做我需要做的事。

我听说使用 strtok 不好，或者至少有更好的方法可以做到这一点。我不知道如何为要绕过的代码添加额外的“标志”(如我代码中的逗号)。

例如:
3,875,837 file1.ext
3437281文件二.txt

我已经开始做我想做的事了。

field1 = 3  
field2 = 875  
field3 = 837

但是我希望这 2 个输入上的其余字符串进入单独的 char 数组并打印如下:

field4 = file1  
field5 = ext  

和

field4 = document  
field5 = two  
field6 = txt

或者，我现在在想，我是否可以提取该 char 数组字段 的最后一次迭代，以便通过完全相同的代码使用另一个循环，除了替换 ， 有 ' ' 空格吗？

Answer 1

很大程度上取决于您要将数据用于什么目的。如何在代码等其他地方使用它。

我想我经常会像这样使用简单的迭代进行解析。如果你想使用 sscanf 这可能会有所帮助；举个例子:

#include <stdio.h>

int prnt_fields(char **ptr)
{
    char field[128];
    int n;
    int i = 0;

    printf("Item {\n");
    while (**ptr) {
        if(sscanf(*ptr, "%127[^\t\n., ]%n", field, &n) != 1)
            break;
        printf("  %d => '%s'\n", i++, field);
        (*ptr) += n;
        /* To handle multiple spaces tabs etc.: */
        if(sscanf(*ptr, "%127[ \t.,]%n", field, &n))
            (*ptr) += n;
        /* Or:
        n = 0;
        sscanf(*ptr, "%*[ \t.,]%n", &n);
        (*ptr) += n;
        */

        if (**ptr == '\n') {
            printf("} OK!\n");
            (*ptr)++;
            return **ptr != '\0';
        }
    }
    /* Should never end here unless input is invalid;
     * aka not separated with , \n or over long fields (>127) */
    printf("} something failed!\n");
    return 0;
}

int main(void)
{
    char *tst = "3,875,837 file1.ext\n"
        "6,875,847 file2.ext\n"
        "3,437,281 document two.txt\n"
        "9,991,123\tdrei.txt\n"
        "4,494,123        vier    fünf .    txt\n"
        ;
    char field[128];
    int n;
    char *ptr = tst;
    int i = 0;

    while (*ptr) {
        if(sscanf(ptr, "%127[^, \n.]%n", field, &n) != 1)
            break;
        printf("field%d = '%s'\n", i++, field);
        ptr += n+1;

        /* If one want to validate separator

        ptr += n;
        if (*ptr != ',' && *ptr != ' ' && *ptr != '\n')
            break;
        ++ptr;

        */
    }

    ptr = tst;

    printf("\n---------------\n");
    while (prnt_fields(&ptr) > 0)
        ;

    return 0;
}

应该给出类似的东西:

field0 = '3'
field1 = '875'
field2 = '837'
...
field18 = '123  drei' <= breaks here
field19 = 'txt'
field20 = '4'
field21 = '494'
field22 = '123'
Item {
  0 => '3'
  1 => '875'
  2 => '837'
  3 => 'file1'
  4 => 'ext'
} OK!
Item {
  0 => '6'
  1 => '875'
  2 => '847'
  3 => 'file2'
  4 => 'ext'
} OK!
Item {
  0 => '3'
  1 => '437'
  2 => '281'
  3 => 'document'
  4 => 'two'
  5 => 'txt'
} OK!
Item {
  0 => '9'
  1 => '991'
  2 => '123'
  3 => 'drei'
  4 => 'txt'
} OK!
Item {
  0 => '4'
  1 => '494'
  2 => '123'
  3 => 'vier'
  4 => 'fünf'
  5 => 'txt'
} OK!

---

编辑:

好的。这可以做得更干净、更漂亮，但您可能会有一个想法:

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

struct file_data {
    struct date {
        int y;
        int m;
        int d;
    } date;
    struct time {
        int h;
        int m;
    } time;
    int size_prt[8];    /* max 2^63 : 9223372036854775808 bytes */
    double size;
    char name[512];
    char ext[16];
    char ext_tr[16];
    char name_prt[32][128]; /* should be malloc or ptrs or done in func or.. */
};

/* Default */
static const struct file_data file_def = {
    {0,0,0},{0,0},{-1},0,{'\0'},{'\0'},{'\0'},{{'\0'}}
};

void prnt_filedata(FILE *fh, struct file_data fd)
{
    int i = 0;
    fprintf(fh,
        "File { \n"
        "  Date: %4d-%02d-%02d\n"
        "  Time: %02d:%02d\n"
        "  Size: %.f\n"
        "  Size: %.2f K\n"
        "  Size: %.2f M\n"
        "  Size: %.2f G\n"
        "  Name: '%s'\n"
        "  Ext : '%s'\n"
        "  ExtT: '%s'\n"
        "  Szpt: ",
        fd.date.y, fd.date.m, fd.date.d,
        fd.time.h, fd.time.m,
        fd.size,
        (fd.size / (1 << 10)),
        (fd.size / (1 << 20)),
        (fd.size / (1 << 30)),
        fd.name,
        fd.ext,
        fd.ext_tr
        );
    while (fd.size_prt[i] != -1)
        fprintf(fh, "%d ", fd.size_prt[i++]);
    fprintf(fh, "\n  Fprt: ");
    i = 0;
    while (*fd.name_prt[i])
        fprintf(fh, "'%s' ", fd.name_prt[i++]);
    fprintf(fh, "\n}\n");
}

int extr_file_data(char **ptr, struct file_data *fd)
{
    int i;
    int n;
    char size[26];
    char name[512];
    char *p;
    *fd = file_def;

    while (**ptr) {
        if (sscanf(*ptr,
            "%4d-%2d-%2d %d:%d %25[0123456789,] %511[^\n]%n",
            &fd->date.y, &fd->date.m, &fd->date.d,
            &fd->time.h, &fd->time.m,
            size, name, &n) != 7) {
            fprintf(stderr,
                " * ERR; Unable to extract from %s\n",
                *ptr);
            return 0;
        }
        (*ptr) += n;
        p = size;
        i = 0;
        /* Size parts + total */
        while (*p && i < 7) {
            fd->size_prt[i] = (int)strtol(p, &p, 0);
            fd->size *= 1000;
            fd->size += fd->size_prt[i++];
            if (*p) ++p;
        }
        fd->size_prt[i] = -1;   /* flag next to last  */
        /* get .ext */
        if ((p = strrchr(name, '.')) != NULL) {
            strncpy(fd->name, name, p - name);
            strncpy(fd->ext, p + 1, 16);
            /* trimmed ext */
            if (sscanf(fd->ext, "%15s", fd->ext_tr) != 1)
                *fd->ext_tr = '\0';
        } else {
            strncpy(fd->name, name, 511);
        }
        /* get trimmed parts of name */
        p = fd->name;
        i = 0;
        while (sscanf(p, "%127s%n", fd->name_prt[i++], &n) == 1 && i < 32)
            p+=n;
            ;
        *fd->name_prt[n] = '\0';

        if (**ptr == '\n')
            (*ptr)++;
        return **ptr != '\0';
    }
    return 0;
}

int main(void)
{
    char *tst =
        "2012-04-18 13:28                  32 ein.ext\n"
        "2012-04-18 13:28       2,446,875,847 zwei.xt  \n"
        "2012-04-18 13:28                   0 drei  .xt\n"
        "2012-04-18 13:28 7,694,587,183,883,665 vier fünf.txt\n"
        "2012-04-18 13:28 9,991,123\t\tsechs\n"
        "2012-04-18 13:28 4,494,123        sieben     acht  .   txt\n"
        ;
    char *ptr = tst;
    struct file_data fd;

    while (extr_file_data(&ptr, &fd) > 0)
        prnt_filedata(stdout, fd);
    prnt_filedata(stdout, fd);

    return 0;
}

应该给:

...
File { 
  Date: 2012-04-18
  Time: 13:28
  Size: 2446875847
  Size: 2389527.19 K
  Size: 2333.52 M
  Size: 2.28 G
  Name: 'zwei'
  Ext : 'xt  '
  ExtT: 'xt'
  Szpt: 2 446 875 847 
  Fprt: 'zwei' 
}
...
File { 
  Date: 2012-04-18
  Time: 13:28
  Size: 4494123
  Size: 4388.79 K
  Size: 4.29 M
  Size: 0.00 G
  Name: 'sieben     acht  '
  Ext : '   txt'
  ExtT: 'txt'
  Szpt: 4 494 123 
  Fprt: 'sieben' 'acht' 
}
...

---

编辑(再次)；抱歉，只是一个奇怪的转变，我在测试后忘记更改。