1explain_strtod(3)          Library Functions Manual          explain_strtod(3)
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NAME

6       explain_strtod - explain strtod(3) errors
7

SYNOPSIS

9       #include <libexplain/strtod.h>
10       const char *explain_strtod(const char *nptr, char **endptr);
11       const char *explain_errno_strtod(int errnum, const char *nptr, char
12       **endptr);
13       void explain_message_strtod(char *message, int message_size, const char
14       *nptr, char **endptr);
15       void explain_message_errno_strtod(char *message, int message_size, int
16       errnum, const char *nptr, char **endptr);
17

DESCRIPTION

19       These functions may be used to obtain explanations for errors  returned
20       by the strtod(3) system call.
21
22   explain_strtod
23       const char *explain_strtod(const char *nptr, char **endptr);
24
25       The  explain_strtod  function  is  used  to obtain an explanation of an
26       error returned by the strtod(3) system call. The least the message will
27       contain  is  the  value of strerror(errno), but usually it will do much
28       better, and indicate the underlying cause in more detail.
29
30       The errno global variable will be used to obtain the error value to  be
31       decoded.
32
33       nptr    The  original  nptr,  exactly as passed to the strtod(3) system
34               call.
35
36       endptr  The original endptr, exactly as passed to the strtod(3)  system
37               call.
38
39       Returns:
40               The message explaining the error. This message buffer is shared
41               by all libexplain functions which do not  supply  a  buffer  in
42               their argument list.  This will be overwritten by the next call
43               to any libexplain function which shares this buffer,  including
44               other threads.
45
46       Note: This function is not thread safe, because it shares a return buf‐
47       fer across all threads, and many other functions in this library.
48
49       Example: This function is intended to be used in a fashion  similar  to
50       the following example:
51              double result = strtod(nptr, endptr);
52              if (result < 0)
53              {
54                  fprintf(stderr, "%s\n", explain_strtod(nptr, endptr));
55                  exit(EXIT_FAILURE);
56              }
57
58       The  above  code  example is available pre‐packaged as the explain_str‐
59       tod_or_die(3) function.
60
61   explain_errno_strtod
62       const char *explain_errno_strtod(int errnum, const char *nptr, char
63       **endptr);
64
65       The  explain_errno_strtod  function is used to obtain an explanation of
66       an error returned by the strtod(3) system call. The least  the  message
67       will  contain  is  the value of strerror(errno), but usually it will do
68       much better, and indicate the underlying cause in more detail.
69
70       errnum  The error value to be decoded, usually obtained from the  errno
71               global  variable  just  before this function is called. This is
72               necessary if you need to call any code between the system  call
73               to  be explained and this function, because many libc functions
74               will alter the value of errno.
75
76       nptr    The original nptr, exactly as passed to  the  strtod(3)  system
77               call.
78
79       endptr  The  original endptr, exactly as passed to the strtod(3) system
80               call.
81
82       Returns:
83               The message explaining the error. This message buffer is shared
84               by  all  libexplain  functions  which do not supply a buffer in
85               their argument list.  This will be overwritten by the next call
86               to  any libexplain function which shares this buffer, including
87               other threads.
88
89       Note: This function is not thread safe, because it shares a return buf‐
90       fer across all threads, and many other functions in this library.
91
92       Example:  This  function is intended to be used in a fashion similar to
93       the following example:
94              double result = strtod(nptr, endptr);
95              if (result < 0)
96              {
97                  int err = errno;
98                  fprintf(stderr, "%s\n", explain_errno_strtod(err, nptr,
99                  endptr));
100                  exit(EXIT_FAILURE);
101              }
102
103       The  above  code  example is available pre‐packaged as the explain_str‐
104       tod_or_die(3) function.
105
106   explain_message_strtod
107       void explain_message_strtod(char *message, int message_size, const char
108       *nptr, char **endptr);
109
110       The explain_message_strtod function is used to obtain an explanation of
111       an error returned by the strtod(3) system call. The least  the  message
112       will  contain  is  the value of strerror(errno), but usually it will do
113       much better, and indicate the underlying cause in more detail.
114
115       The errno global variable will be used to obtain the error value to  be
116       decoded.
117
118       message The location in which to store the returned message. If a suit‐
119               able message return buffer is supplied, this function is thread
120               safe.
121
122       message_size
123               The  size  in  bytes  of  the  location  in  which to store the
124               returned message.
125
126       nptr    The original nptr, exactly as passed to  the  strtod(3)  system
127               call.
128
129       endptr  The  original endptr, exactly as passed to the strtod(3) system
130               call.
131
132       Example: This function is intended to be used in a fashion  similar  to
133       the following example:
134              double result = strtod(nptr, endptr);
135              if (result < 0)
136              {
137                  char message[3000];
138                  explain_message_strtod(message, sizeof(message), nptr,
139                  endptr);
140                  fprintf(stderr, "%s\n", message);
141                  exit(EXIT_FAILURE);
142              }
143
144       The above code example is available pre‐packaged  as  the  explain_str‐
145       tod_or_die(3) function.
146
147   explain_message_errno_strtod
148       void explain_message_errno_strtod(char *message, int message_size, int
149       errnum, const char *nptr, char **endptr);
150
151       The explain_message_errno_strtod function is used to obtain an explana‐
152       tion  of  an error returned by the strtod(3) system call. The least the
153       message will contain is the value of strerror(errno),  but  usually  it
154       will do much better, and indicate the underlying cause in more detail.
155
156       message The location in which to store the returned message. If a suit‐
157               able message return buffer is supplied, this function is thread
158               safe.
159
160       message_size
161               The  size  in  bytes  of  the  location  in  which to store the
162               returned message.
163
164       errnum  The error value to be decoded, usually obtained from the  errno
165               global  variable  just  before this function is called. This is
166               necessary if you need to call any code between the system  call
167               to  be explained and this function, because many libc functions
168               will alter the value of errno.
169
170       nptr    The original nptr, exactly as passed to  the  strtod(3)  system
171               call.
172
173       endptr  The  original endptr, exactly as passed to the strtod(3) system
174               call.
175
176       Example: This function is intended to be used in a fashion  similar  to
177       the following example:
178              double result = strtod(nptr, endptr);
179              if (result < 0)
180              {
181                  int err = errno;
182                  char message[3000];
183                  explain_message_errno_strtod(message, sizeof(message), err,
184                  nptr, endptr);
185                  fprintf(stderr, "%s\n", message);
186                  exit(EXIT_FAILURE);
187              }
188
189       The above code example is available pre‐packaged  as  the  explain_str‐
190       tod_or_die(3) function.
191

SEE ALSO

193       strtod(3)
194               convert ASCII string to floating‐point number
195
196       explain_strtod_or_die(3)
197               convert ASCII string to floating‐point number and report errors
198
200       libexplain version 0.40
201       Copyright (C) 2009 Peter Miller
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205                                                             explain_strtod(3)
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