これは、Kernighan と Plauger によるThe Practice of Programmingの CSV コードに基づいたコードで、奇妙で不正な形式の CSV データを処理するように適合されています。（それほど難しいことではありませんでした。すでにメインコードが機能してパッケージ化されているため、CSV出力関数を追加しadvquoted()、この質問の奇妙な形式を処理するように関数を変更する必要がありました.
csv2.h
/*
@(#)File: $RCSfile: csv2.h,v $
@(#)Version: $Revision: 2.1 $
@(#)Last changed: $Date: 2012/11/01 22:23:07 $
@(#)Purpose: Scanner for Comma Separated Variable (CSV) Data
@(#)Author: J Leffler
@(#)Origin: Kernighan & Pike, 'The Practice of Programming'
*/
/*TABSTOP=4*/
#ifndef CSV2_H
#define CSV2_H
#ifdef __cplusplus
extern "C" {
#endif
#ifdef MAIN_PROGRAM
#ifndef lint
/* Prevent over-aggressive optimizers from eliminating ID string */
const char jlss_id_csv2_h[] = "@(#)$Id: csv2.h,v 2.1 2012/11/01 22:23:07 jleffler Exp $";
#endif /* lint */
#endif /* MAIN_PROGRAM */
#include <stdio.h>
extern char *csvgetline(FILE *ifp); /* Read next input line */
extern char *csvgetfield(size_t n); /* Return field n */
extern size_t csvnfield(void); /* Return number of fields */
extern void csvreset(void); /* Release space used by CSV */
extern int csvputfield(FILE *ofp, const char *field);
extern int csvputline(FILE *ofp, char **fields, int nfields);
extern void csvseteol(const char *eol);
#ifdef __cplusplus
}
#endif
#endif /* CSV2_H */
csv2.c
/*
@(#)File: $RCSfile: csv2.c,v $
@(#)Version: $Revision: 2.1 $
@(#)Last changed: $Date: 2012/11/01 22:23:07 $
@(#)Purpose: Scanner for Comma Separated Variable (CSV) Data
@(#)Modification: Deal with specific malformed CSV
@(#)Author: J Leffler
@(#)Origin: Kernighan & Pike, 'The Practice of Programming'
*/
/*TABSTOP=4*/
#ifndef lint
/* Prevent over-aggressive optimizers from eliminating ID string */
const char jlss_id_csv2_c[] = "@(#)$Id: csv2.c,v 2.1 2012/11/01 22:23:07 jleffler Exp $";
#endif /* lint */
/*
** See RFC 4180 (http://www.ietf.org/rfc/rfc4180.txt).
**
** Specific malformed CSV - see SO 13183644 (http://stackoverflow.com/questions/13183644).
** Data contains malformed CSV fields like: OK,""this is a problem"",OK
** Two (but not three) field quotes at the start extract as "this is a problem" (with the quotes).
*/
#include "csv2.h"
#include <stdlib.h>
#include <string.h>
enum { NOMEM = -2 };
static char *line = 0; /* Input line */
static char *sline = 0; /* Split line */
static size_t maxline = 0; /* Size of line[] and sline[] */
static char **field = 0; /* Field pointers */
static size_t maxfield = 0; /* Size of field[] */
static size_t nfield = 0; /* Number of fields */
static char fieldsep[]= ","; /* Field separator characters */
static char fieldquote = '"'; /* Quote character */
static char eolstr[8] = "\n";
void csvreset(void)
{
free(line);
free(sline);
free(field);
line = 0;
sline = 0;
field = 0;
maxline = maxfield = nfield = 0;
}
static int endofline(FILE *ifp, int c)
{
int eol = (c == '\r' || c == '\n');
if (c == '\r')
{
c = getc(ifp);
if (c != '\n' && c != EOF)
ungetc(c, ifp);
}
return(eol);
}
/* Modified to deal with specific malformed CSV */
static char *advquoted(char *p)
{
size_t i;
size_t j;
if (p[0] == fieldquote && (p[1] != *fieldsep && p[1] != fieldquote))
{
/* Malformed CSV: ""some stuff"" --> "some stuff" */
/* Find "\"\"," or "\"\"\0" to mark end of field */
/* If we don't find it, drop through to 'regular' case */
char *eof = strstr(&p[2], "\"\"");
if (eof != 0 && (eof[2] == *fieldsep || eof[2] == '\0'))
{
p[eof + 1 - p] = '\0';
return(eof + 2);
}
}
for (i = j = 0; p[j] != '\0'; i++, j++)
{
if (p[j] == fieldquote && p[++j] != fieldquote)
{
size_t k = strcspn(p+j, fieldsep);
memmove(p+i, p+j, k); // 1 -> i fixing transcription error
i += k;
j += k;
break;
}
p[i] = p[j];
}
p[i] = '\0';
return(p + j);
}
static int split(void)
{
char *p;
char **newf;
char *sepp;
int sepc;
nfield = 0;
if (line[0] == '\0')
return(0);
strcpy(sline, line);
p = sline;
do
{
if (nfield >= maxfield)
{
maxfield *= 2;
newf = (char **)realloc(field, maxfield * sizeof(field[0]));
if (newf == 0)
return NOMEM;
field = newf;
}
if (*p == fieldquote)
sepp = advquoted(++p);
else
sepp = p + strcspn(p, fieldsep);
sepc = sepp[0];
sepp[0] = '\0';
field[nfield++] = p;
p = sepp + 1;
} while (sepc == ',');
return(nfield);
}
char *csvgetline(FILE *ifp)
{
size_t i;
int c;
if (line == NULL)
{
/* Allocate on first call */
maxline = maxfield = 1;
line = (char *)malloc(maxline); /*=C++=*/
sline = (char *)malloc(maxline); /*=C++-*/
field = (char **)malloc(maxfield*sizeof(field[0])); /*=C++=*/
if (line == NULL || sline == NULL || field == NULL)
{
csvreset();
return(NULL); /* out of memory */
}
}
for (i = 0; (c = getc(ifp)) != EOF && !endofline(ifp, c); i++)
{
if (i >= maxline - 1)
{
char *newl;
char *news;
maxline *= 2;
newl = (char *)realloc(line, maxline); /*=C++=*/
news = (char *)realloc(sline, maxline); /*=C++-*/
if (newl == NULL || news == NULL)
{
csvreset();
return(NULL); /* out of memory */
}
line = newl;
sline = news;
}
line[i] = c;
}
line[i] = '\0';
if (split() == NOMEM)
{
csvreset();
return(NULL);
}
return((c == EOF && i == 0) ? NULL : line);
}
char *csvgetfield(size_t n)
{
if (n >= nfield)
return(0);
return(field[n]);
}
size_t csvnfield(void)
{
return(nfield);
}
int csvputfield(FILE *ofp, const char *ofield)
{
const char escapes[] = "\",\r\n";
if (strpbrk(ofield, escapes) != 0)
{
size_t len = strlen(ofield) + 2;
const char *pos = ofield;
while ((pos = strchr(pos, '"')) != 0)
{
len++;
pos++;
}
char *space = malloc(len+1);
if (space == 0)
return EOF;
char *cpy = space;
pos = ofield;
*cpy++ = '"';
char c;
while ((c = *pos++) != '\0')
{
if (c == '"')
*cpy++ = c;
*cpy++ = c;
}
*cpy++ = '"';
*cpy = '\0';
int rc = fputs(space, ofp);
free(space);
return rc;
}
else
return fputs(ofield, ofp);
}
int csvputline(FILE *ofp, char **fields, int nfields)
{
for (int i = 0; i < nfields; i++)
{
if (i > 0)
putc(',', ofp);
if (csvputfield(ofp, fields[i]) == EOF)
return EOF;
}
return(fputs(eolstr, ofp));
}
void csvseteol(const char *eol)
{
size_t nbytes = strlen(eol);
if (nbytes >= sizeof(eolstr))
nbytes = sizeof(eolstr) - 1;
memmove(eolstr, eol, nbytes);
eolstr[nbytes] = '\0';
}
#ifdef TEST
int main(void)
{
char *in_line;
while ((in_line = csvgetline(stdin)) != 0)
{
size_t n = csvnfield();
char *fields[n]; /* C99 VLA */
printf("line = '%s'\n", in_line);
for (size_t i = 0; i < n; i++)
{
printf("field[%zu] = '%s'\n", i, csvgetfield(i));
printf("field[%zu] = [", i);
csvputfield(stdout, csvgetfield(i));
fputs("]\n", stdout);
fields[i] = csvgetfield(i);
}
printf("fields[0..%zu] = ", n-1);
csvputline(stdout, fields, n);
}
return(0);
}
#endif /* TEST */
でコードをコンパイルして、サンプル関数-DTESTを含むプログラムを作成します。main()C99 コンパイラが必要です。のコードはmain()VLA (可変長配列) を使用しています。動的なメモリ割り当てまたは悲観的な (過剰な) メモリ割り当てを使用して、これを回避できます (最近では、数千のポインターの配列がほとんどのシステムを殺すことはありませんが、1 行に数千のフィールドを持つ CSV ファイルはほとんどありません)。
サンプルデータ
質問のデータに厳密に基づいています。
009098,0981098094,"something","something else",""this one, well, is a problem"", "another thing"
123458,1234561007,"anything","nothing else",""this one, well, is a problem"","dohicky
503458,1234598094,"nothing","everything else","""this one, well, it isn't a problem""","abelone"
610078,1236100794,"everything","anything else","this ""isn't a problem"", he said.","Orcas Rule"
出力例
line = '009098,0981098094,"something","something else",""this one, well, is a problem"", "another thing"'
field[0] = '009098'
field[0] = [009098]
field[1] = '0981098094'
field[1] = [0981098094]
field[2] = 'something'
field[2] = [something]
field[3] = 'something else'
field[3] = [something else]
field[4] = '"this one, well, is a problem"'
field[4] = ["""this one, well, is a problem"""]
field[5] = ' "another thing"'
field[5] = [" ""another thing"""]
fields[0..5] = 009098,0981098094,something,something else,"""this one, well, is a problem"""," ""another thing"""
line = '123458,1234561007,"anything","nothing else",""this one, well, is a problem"","dohicky'
field[0] = '123458'
field[0] = [123458]
field[1] = '1234561007'
field[1] = [1234561007]
field[2] = 'anything'
field[2] = [anything]
field[3] = 'nothing else'
field[3] = [nothing else]
field[4] = '"this one, well, is a problem"'
field[4] = ["""this one, well, is a problem"""]
field[5] = 'dohicky'
field[5] = [dohicky]
fields[0..5] = 123458,1234561007,anything,nothing else,"""this one, well, is a problem""",dohicky
line = '503458,1234598094,"nothing","everything else","""this one, well, it isn't a problem""","abelone"'
field[0] = '503458'
field[0] = [503458]
field[1] = '1234598094'
field[1] = [1234598094]
field[2] = 'nothing'
field[2] = [nothing]
field[3] = 'everything else'
field[3] = [everything else]
field[4] = '"this one, well, it isn't a problem"'
field[4] = ["""this one, well, it isn't a problem"""]
field[5] = 'abelone'
field[5] = [abelone]
fields[0..5] = 503458,1234598094,nothing,everything else,"""this one, well, it isn't a problem""",abelone
line = '610078,1236100794,"everything","anything else","this ""isn't a problem"", he said.","Orcas Rule"'
field[0] = '610078'
field[0] = [610078]
field[1] = '1236100794'
field[1] = [1236100794]
field[2] = 'everything'
field[2] = [everything]
field[3] = 'anything else'
field[3] = [anything else]
field[4] = 'this "isn't a problem", he said.'
field[4] = ["this ""isn't a problem"", he said."]
field[5] = 'Orcas Rule'
field[5] = [Orcas Rule]
fields[0..5] = 610078,1236100794,everything,anything else,"this ""isn't a problem"", he said.",Orcas Rule
フィールドは 2 回印刷されます。1 回はフィールド抽出をテストするため、もう 1 回はフィールド印刷をテストするためです。csvputline()ファイルを不正な形式の CSV から適切な形式の CSV に変換する以外は、印刷を削除して出力を簡素化します。