/src/igraph/src/core/printing.c

Source
/*
   igraph library.
   Copyright (C) 2012  Gabor Csardi <csardi.gabor@gmail.com>
   334 Harvard street, Cambridge, MA 02139 USA

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
   02110-1301 USA

*/

#include "igraph_complex.h"
#include "igraph_error.h"
#include "igraph_types.h"

#include <float.h>

/* The number of digits chosen here will be used in all places where
 * igraph_real_fprintf_precise() is used, including all textual graph
 * formats such as GML, GraphML, Pajek, etc. DBL_DIG digits are sufficient
 * to preserve the decimal representation during a
 * decimal (textual) -> binary -> decimal (textual) round-trip conversion.
 * This many digits are however not sufficient for a lossless
 * binary -> decimal -> binary conversion. Thus, writing numerical attributes
 * to a file and reading them back in may cause a tiny change in the last
 * binary digit of numbers. This change is minute, always smaller than 10^-15
 * times the original number, thus acceptable.
 *
 * We could output more digits, but that would come with its own problem:
 * It would sometimes cause a change in the decimal representation originally
 * input by users, which is surprising and confusing. For example,
 *
 * printf("%.17g\n", 100.1)
 *
 * outputs 100.09999999999999 instead of 100.1. We can prevent this by
 * using DBL_DIG == 15 digits instead of 17, which would be required
 * for a lossless binary -> decimal -> binary round-tripping.
 *
 * This justifies using DBL_DIG digits, and not more, in all places.
 */
#ifdef DBL_DIG
    /* Use DBL_DIG to determine the maximum precision used for %g */
    #define IGRAPH_REAL_PRINTF_PRECISE_FORMAT "%." IGRAPH_I_STRINGIFY(DBL_DIG) "g"
#else
    /* Assume a precision of 15 digits for %g, which is what IEEE-754 doubles require. */
    #define IGRAPH_REAL_PRINTF_PRECISE_FORMAT "%.15g"
#endif

int igraph_real_fprintf(FILE *file, igraph_real_t val) {
    if (isfinite(val)) {
        return fprintf(file, "%g", val);
    } else if (isnan(val)) {
        return fprintf(file, "NaN");
    } else if (isinf(val)) {
        if (val < 0) {
            return fprintf(file, "-Inf");
        } else {
            return fprintf(file, "Inf");
        }
    }
    IGRAPH_FATAL("Value is not finite, not infinite and not NaN either!");  /* LCOV_EXCL_LINE */
}

#ifndef USING_R
int igraph_real_printf(igraph_real_t val) {
    return igraph_real_fprintf(stdout, val);
}
#endif

int igraph_real_fprintf_aligned(FILE *file, int width, igraph_real_t val) {
    if (isfinite(val)) {
        return fprintf(file, "%*g", width, val);
    } else if (isnan(val)) {
        return fprintf(file, "%*s", width, "NaN");
    } else if (isinf(val)) {
        if (val < 0) {
            return fprintf(file, "%*s", width, "-Inf");
        } else {
            return fprintf(file, "%*s", width, "Inf");
        }
    }
    IGRAPH_FATAL("Value is not finite, not infinite and not NaN either!");  /* LCOV_EXCL_LINE */
}

#ifndef USING_R
int igraph_real_printf_aligned(int width, igraph_real_t val) {
    return igraph_real_fprintf_aligned(stdout, width, val);
}
#endif

int igraph_real_snprintf(char *str, size_t size, igraph_real_t val) {
    if (isfinite(val)) {
        return snprintf(str, size, "%g", val);
    } else if (isnan(val)) {
        return snprintf(str, size, "NaN");
    } else if (isinf(val)) {
        if (val < 0) {
            return snprintf(str, size, "-Inf");
        } else {
            return snprintf(str, size, "Inf");
        }
    }
    IGRAPH_FATAL("Value is not finite, not infinite and not NaN either!");  /* LCOV_EXCL_LINE */
}

int igraph_real_fprintf_precise(FILE *file, igraph_real_t val) {
    if (isfinite(val)) {
        return fprintf(file, IGRAPH_REAL_PRINTF_PRECISE_FORMAT, val);
    } else if (isnan(val)) {
        return fprintf(file, "NaN");
    } else if (isinf(val)) {
        if (val < 0) {
            return fprintf(file, "-Inf");
        } else {
            return fprintf(file, "Inf");
        }
    }
    IGRAPH_FATAL("Value is not finite, not infinite and not NaN either!");  /* LCOV_EXCL_LINE */
}

#ifndef USING_R
int igraph_real_printf_precise(igraph_real_t val) {
    return igraph_real_fprintf_precise(stdout, val);
}
#endif

int igraph_real_snprintf_precise(char *str, size_t size, igraph_real_t val) {
    if (isfinite(val)) {
        return snprintf(str, size, IGRAPH_REAL_PRINTF_PRECISE_FORMAT, val);
    } else if (isnan(val)) {
        return snprintf(str, size, "NaN");
    } else if (isinf(val)) {
        if (val < 0) {
            return snprintf(str, size, "-Inf");
        } else {
            return snprintf(str, size, "Inf");
        }
    }
    IGRAPH_FATAL("Value is not finite, not infinite and not NaN either!");  /* LCOV_EXCL_LINE */
}

#define PROPAGATE() \
    do { \
        if (res < 0) { \
            return -1; \
        } \
        cnt += res; \
    } while (0)

int igraph_complex_fprintf(FILE *file, igraph_complex_t val) {
    int res, cnt = 0;
    igraph_real_t re = IGRAPH_REAL(val), im = IGRAPH_IMAG(val);
    res = igraph_real_fprintf(file, re);
    PROPAGATE();
    if (! signbit(im)) {
        res = fprintf(file, "+");
        PROPAGATE();
    }
    res = igraph_real_fprintf(file, im);
    PROPAGATE();
    res = fprintf(file, "i");
    PROPAGATE();
    return cnt;
}

#undef PROPAGATE

#ifndef USING_R
int igraph_complex_printf(igraph_complex_t val) {
    return igraph_complex_fprintf(stdout, val);
}
#endif

#define PROPAGATE() \
    do { \
        if (res < 0) { \
            return -1; \
        } \
        cnt += res; \
        /* remember that 'size' is unsigned, can't check if size - res < 0! */ \
        if (size > (size_t) res) size -= res; \
        else size = 0; \
        if (size == 0) str = NULL; else str += res; \
    } while (0)

int igraph_complex_snprintf(char *str, size_t size, igraph_complex_t val) {
    int res, cnt = 0;
    igraph_real_t re = IGRAPH_REAL(val), im = IGRAPH_IMAG(val);
    res = igraph_real_snprintf(str, size, re);
    PROPAGATE();
    if (! signbit(im)) {
        res = snprintf(str, size, "+");
        PROPAGATE();
    }
    res = igraph_real_snprintf(str, size, im);
    PROPAGATE();
    res = snprintf(str, size, "i");
    PROPAGATE();
    return cnt;
}

int igraph_complex_fprintf_aligned(FILE *file, int width, igraph_complex_t val) {
    /* Most characters produces by %g is 13, so including 'i' and null terminator we
     * need up to 13 + 13 + 1 + 1 = 28 characters in total. */
    char buf[28];

    if (igraph_complex_snprintf(buf, sizeof(buf) / sizeof(buf[0]), val) < 0) {
        return -1;
    }
    return fprintf(file, "%*s", width, buf);
}

#ifndef USING_R
int igraph_complex_printf_aligned(int width, igraph_complex_t val) {
    return igraph_complex_fprintf_aligned(stdout, width, val);
}
#endif

#undef PROPAGATE

Coverage Report

Created: 2026-08-11 07:20

Line	Count	Source
1		/*
2		igraph library.
3		Copyright (C) 2012 Gabor Csardi <csardi.gabor@gmail.com>
4		334 Harvard street, Cambridge, MA 02139 USA
5
6		This program is free software; you can redistribute it and/or modify
7		it under the terms of the GNU General Public License as published by
8		the Free Software Foundation; either version 2 of the License, or
9		(at your option) any later version.
10
11		This program is distributed in the hope that it will be useful,
12		but WITHOUT ANY WARRANTY; without even the implied warranty of
13		MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14		GNU General Public License for more details.
15
16		You should have received a copy of the GNU General Public License
17		along with this program; if not, write to the Free Software
18		Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
19		02110-1301 USA
20
21		*/
22
23		#include "igraph_complex.h"
24		#include "igraph_error.h"
25		#include "igraph_types.h"
26
27		#include <float.h>
28
29		/* The number of digits chosen here will be used in all places where
30		* igraph_real_fprintf_precise() is used, including all textual graph
31		* formats such as GML, GraphML, Pajek, etc. DBL_DIG digits are sufficient
32		* to preserve the decimal representation during a
33		* decimal (textual) -> binary -> decimal (textual) round-trip conversion.
34		* This many digits are however not sufficient for a lossless
35		* binary -> decimal -> binary conversion. Thus, writing numerical attributes
36		* to a file and reading them back in may cause a tiny change in the last
37		* binary digit of numbers. This change is minute, always smaller than 10^-15
38		* times the original number, thus acceptable.
39		*
40		* We could output more digits, but that would come with its own problem:
41		* It would sometimes cause a change in the decimal representation originally
42		* input by users, which is surprising and confusing. For example,
43		*
44		* printf("%.17g\n", 100.1)
45		*
46		* outputs 100.09999999999999 instead of 100.1. We can prevent this by
47		* using DBL_DIG == 15 digits instead of 17, which would be required
48		* for a lossless binary -> decimal -> binary round-tripping.
49		*
50		* This justifies using DBL_DIG digits, and not more, in all places.
51		*/
52		#ifdef DBL_DIG
53		/* Use DBL_DIG to determine the maximum precision used for %g */
54	6.28M	#define IGRAPH_REAL_PRINTF_PRECISE_FORMAT "%." IGRAPH_I_STRINGIFY(DBL_DIG) "g"
55		#else
56		/* Assume a precision of 15 digits for %g, which is what IEEE-754 doubles require. */
57		#define IGRAPH_REAL_PRINTF_PRECISE_FORMAT "%.15g"
58		#endif
59
60	0	int igraph_real_fprintf(FILE *file, igraph_real_t val) {
61	0	if (isfinite(val)) {
62	0	return fprintf(file, "%g", val);
63	0	} else if (isnan(val)) {
64	0	return fprintf(file, "NaN");
65	0	} else if (isinf(val)) {
66	0	if (val < 0) {
67	0	return fprintf(file, "-Inf");
68	0	} else {
69	0	return fprintf(file, "Inf");
70	0	}
71	0	}
72	0	IGRAPH_FATAL("Value is not finite, not infinite and not NaN either!"); /* LCOV_EXCL_LINE */
73	0	}
74
75		#ifndef USING_R
76	0	int igraph_real_printf(igraph_real_t val) {
77	0	return igraph_real_fprintf(stdout, val);
78	0	}
79		#endif
80
81	0	int igraph_real_fprintf_aligned(FILE *file, int width, igraph_real_t val) {
82	0	if (isfinite(val)) {
83	0	return fprintf(file, "%*g", width, val);
84	0	} else if (isnan(val)) {
85	0	return fprintf(file, "%*s", width, "NaN");
86	0	} else if (isinf(val)) {
87	0	if (val < 0) {
88	0	return fprintf(file, "%*s", width, "-Inf");
89	0	} else {
90	0	return fprintf(file, "%*s", width, "Inf");
91	0	}
92	0	}
93	0	IGRAPH_FATAL("Value is not finite, not infinite and not NaN either!"); /* LCOV_EXCL_LINE */
94	0	}
95
96		#ifndef USING_R
97	0	int igraph_real_printf_aligned(int width, igraph_real_t val) {
98	0	return igraph_real_fprintf_aligned(stdout, width, val);
99	0	}
100		#endif
101
102	0	int igraph_real_snprintf(char *str, size_t size, igraph_real_t val) {
103	0	if (isfinite(val)) {
104	0	return snprintf(str, size, "%g", val);
105	0	} else if (isnan(val)) {
106	0	return snprintf(str, size, "NaN");
107	0	} else if (isinf(val)) {
108	0	if (val < 0) {
109	0	return snprintf(str, size, "-Inf");
110	0	} else {
111	0	return snprintf(str, size, "Inf");
112	0	}
113	0	}
114	0	IGRAPH_FATAL("Value is not finite, not infinite and not NaN either!"); /* LCOV_EXCL_LINE */
115	0	}
116
117	10.1M	int igraph_real_fprintf_precise(FILE *file, igraph_real_t val) {
118	10.1M	if (isfinite(val)) {
119	6.24M	return fprintf(file, IGRAPH_REAL_PRINTF_PRECISE_FORMAT, val);
120	6.24M	} else if (isnan(val)) {
121	3.84M	return fprintf(file, "NaN");
122	3.84M	} else if (isinf(val)) {
123	31.6k	if (val < 0) {
124	30.0k	return fprintf(file, "-Inf");
125	30.0k	} else {
126	1.60k	return fprintf(file, "Inf");
127	1.60k	}
128	31.6k	}
129	0	IGRAPH_FATAL("Value is not finite, not infinite and not NaN either!"); /* LCOV_EXCL_LINE */
130	0	}
131
132		#ifndef USING_R
133	0	int igraph_real_printf_precise(igraph_real_t val) {
134	0	return igraph_real_fprintf_precise(stdout, val);
135	0	}
136		#endif
137
138	12.6M	int igraph_real_snprintf_precise(char *str, size_t size, igraph_real_t val) {
139	12.6M	if (isfinite(val)) {
140	37.7k	return snprintf(str, size, IGRAPH_REAL_PRINTF_PRECISE_FORMAT, val);
141	12.6M	} else if (isnan(val)) {
142	12.5M	return snprintf(str, size, "NaN");
143	12.5M	} else if (isinf(val)) {
144	30.4k	if (val < 0) {
145	29.5k	return snprintf(str, size, "-Inf");
146	29.5k	} else {
147	948	return snprintf(str, size, "Inf");
148	948	}
149	30.4k	}
150	0	IGRAPH_FATAL("Value is not finite, not infinite and not NaN either!"); /* LCOV_EXCL_LINE */
151	0	}
152
153		#define PROPAGATE() \
154	0	do { \
155	0	if (res < 0) { \
156	0	return -1; \
157	0	} \
158	0	cnt += res; \
159	0	} while (0)
160
161	0	int igraph_complex_fprintf(FILE *file, igraph_complex_t val) {
162	0	int res, cnt = 0;
163	0	igraph_real_t re = IGRAPH_REAL(val), im = IGRAPH_IMAG(val);
164	0	res = igraph_real_fprintf(file, re);
165	0	PROPAGATE();
166	0	if (! signbit(im)) {
167	0	res = fprintf(file, "+");
168	0	PROPAGATE();
169	0	}
170	0	res = igraph_real_fprintf(file, im);
171	0	PROPAGATE();
172	0	res = fprintf(file, "i");
173	0	PROPAGATE();
174	0	return cnt;
175	0	}
176
177		#undef PROPAGATE
178
179		#ifndef USING_R
180	0	int igraph_complex_printf(igraph_complex_t val) {
181	0	return igraph_complex_fprintf(stdout, val);
182	0	}
183		#endif
184
185		#define PROPAGATE() \
186	0	do { \
187	0	if (res < 0) { \
188	0	return -1; \
189	0	} \
190	0	cnt += res; \
191	0	/* remember that 'size' is unsigned, can't check if size - res < 0! */ \
192	0	if (size > (size_t) res) size -= res; \
193	0	else size = 0; \
194	0	if (size == 0) str = NULL; else str += res; \
195	0	} while (0)
196
197	0	int igraph_complex_snprintf(char *str, size_t size, igraph_complex_t val) {
198	0	int res, cnt = 0;
199	0	igraph_real_t re = IGRAPH_REAL(val), im = IGRAPH_IMAG(val);
200	0	res = igraph_real_snprintf(str, size, re);
201	0	PROPAGATE();
202	0	if (! signbit(im)) {
203	0	res = snprintf(str, size, "+");
204	0	PROPAGATE();
205	0	}
206	0	res = igraph_real_snprintf(str, size, im);
207	0	PROPAGATE();
208	0	res = snprintf(str, size, "i");
209	0	PROPAGATE();
210	0	return cnt;
211	0	}
212
213	0	int igraph_complex_fprintf_aligned(FILE *file, int width, igraph_complex_t val) {
214		/* Most characters produces by %g is 13, so including 'i' and null terminator we
215		* need up to 13 + 13 + 1 + 1 = 28 characters in total. */
216	0	char buf[28];
217
218	0	if (igraph_complex_snprintf(buf, sizeof(buf) / sizeof(buf[0]), val) < 0) {
219	0	return -1;
220	0	}
221	0	return fprintf(file, "%*s", width, buf);
222	0	}
223
224		#ifndef USING_R
225	0	int igraph_complex_printf_aligned(int width, igraph_complex_t val) {
226		return igraph_complex_fprintf_aligned(stdout, width, val);
227	0	}
228		#endif
229
230		#undef PROPAGATE