Ich versuche aus einem String einen float Wert wie 3.1 einzulesen. Danach möchte ich Komma schieben und und aus 3.1 einen dezimalwert 31 erhalten. Leider steht in meinem int eine Null. float fVar = 0; int iVar = 0; sprintf(fVar,"%f",text); fVar *= 10; iVar = (int)fVar; printf("Wert: %d", iVar); Woran kann es liegen? Nutze AVR Studio mit GCC sprint
icke schrieb:
> Woran kann es liegen?
Es liegt mit Sicherheit daran, dass du kein Buch hast, sondern versuchst
C nach der Methode 'Trial and Error' zu lernen.
Aber auch du wirst lernen, dass das nicht funktioniert.
Auf Un*x: $ man scanf
1 | NAME |
2 | fscanf, scanf, sscanf, vfscanf, vscanf, vsscanf -- input format conversion |
3 | |
4 | LIBRARY |
5 | Standard C Library (libc, -lc) |
6 | |
7 | SYNOPSIS |
8 | #include <stdio.h> |
9 | |
10 | int |
11 | fscanf(FILE *restrict stream, const char *restrict format, ...); |
12 | |
13 | int |
14 | scanf(const char *restrict format, ...); |
15 | |
16 | int |
17 | sscanf(const char *restrict s, const char *restrict format, ...); |
18 | |
19 | #include <stdarg.h> |
20 | #include <stdio.h> |
21 | |
22 | int |
23 | vfscanf(FILE *restrict stream, const char *restrict format, va_list arg); |
24 | |
25 | int |
26 | vscanf(const char *restrict format, va_list arg); |
27 | int |
28 | vsscanf(const char *restrict s, const char *restrict format, va_list arg); |
29 | |
30 | DESCRIPTION |
31 | The scanf() family of functions scans input according to a format, as described below. This format may contain |
32 | conversion specifiers; the results from such conversions, if any, are stored through the pointer arguments. The |
33 | scanf() function reads input from the standard input stream stdin, fscanf() reads input from the stream pointer |
34 | stream, and sscanf() reads its input from the character string pointed to by s. |
35 | |
36 | The vfscanf() function is analogous to vfprintf(3) and reads input from the stream pointer stream using a vari- |
37 | able argument list of pointers (see stdarg(3)). The vscanf() function scans a variable argument list from the |
38 | standard input and the vsscanf() function scans it from a string; these are analogous to the vprintf() and |
39 | vsprintf() functions, respectively. |
40 | |
41 | Each successive pointer argument must correspond properly with each successive conversion specifier (but see the |
42 | * conversion below). All conversions are introduced by the % (percent sign) character. The format string may |
43 | also contain other characters. White space (such as blanks, tabs, or newlines) in the format string match any |
44 | amount of white space, including none, in the input. Everything else matches only itself. Scanning stops when |
45 | an input character does not match such a format character. Scanning also stops when an input conversion cannot |
46 | be made (see below). |
47 | |
48 | Extended locale versions of these functions are documented in scanf_l(3). See xlocale(3) for more information. |
49 | |
50 | CONVERSIONS |
51 | Following the % character introducing a conversion, there may be a number of flag characters, as follows: |
52 | |
53 | * Suppresses assignment. The conversion that follows occurs as usual, but no pointer is used; the result |
54 | of the conversion is simply discarded. |
55 | hh Indicates that the conversion will be one of dioux or n and the next pointer is a pointer to a char |
56 | (rather than int). |
57 | |
58 | h Indicates that the conversion will be one of dioux or n and the next pointer is a pointer to a short int |
59 | (rather than int). |
60 | |
61 | l (ell) Indicates that the conversion will be one of dioux or n and the next pointer is a pointer to a long int |
62 | (rather than int), that the conversion will be one of a, e, f, or g and the next pointer is a pointer to |
63 | double (rather than float), or that the conversion will be one of c, s or [ and the next pointer is a |
64 | pointer to an array of wchar_t (rather than char). |
65 | |
66 | ll (ell ell) |
67 | Indicates that the conversion will be one of dioux or n and the next pointer is a pointer to a long long |
68 | int (rather than int). |
69 | |
70 | L Indicates that the conversion will be one of a, e, f, or g and the next pointer is a pointer to long |
71 | double. |
72 | |
73 | j Indicates that the conversion will be one of dioux or n and the next pointer is a pointer to a intmax_t |
74 | (rather than int). |
75 | |
76 | t Indicates that the conversion will be one of dioux or n and the next pointer is a pointer to a ptrdiff_t |
77 | (rather than int). |
78 | |
79 | z Indicates that the conversion will be one of dioux or n and the next pointer is a pointer to a size_t |
80 | (rather than int). |
81 | |
82 | q (deprecated.) Indicates that the conversion will be one of dioux or n and the next pointer is a pointer |
83 | to a long long int (rather than int). |
84 | |
85 | In addition to these flags, there may be an optional maximum field width, expressed as a decimal integer, between |
86 | the % and the conversion. If no width is given, a default of ``infinity'' is used (with one exception, below); |
87 | otherwise at most this many bytes are scanned in processing the conversion. In the case of the lc, ls and l[ |
88 | conversions, the field width specifies the maximum number of multibyte characters that will be scanned. Before |
89 | conversion begins, most conversions skip white space; this white space is not counted against the field width. |
90 | |
91 | The following conversions are available: |
92 | |
93 | % Matches a literal `%'. That is, ``%%'' in the format string matches a single input `%' character. No con- |
94 | version is done, and assignment does not occur. |
95 | |
96 | d Matches an optionally signed decimal integer; the next pointer must be a pointer to int. |
97 | |
98 | i Matches an optionally signed integer; the next pointer must be a pointer to int. The integer is read in |
99 | base 16 if it begins with `0x' or `0X', in base 8 if it begins with `0', and in base 10 otherwise. Only |
100 | characters that correspond to the base are used. |
101 | |
102 | o Matches an octal integer; the next pointer must be a pointer to unsigned int. |
103 | |
104 | u Matches an optionally signed decimal integer; the next pointer must be a pointer to unsigned int. |
105 | |
106 | x, X Matches an optionally signed hexadecimal integer; the next pointer must be a pointer to unsigned int. |
107 | |
108 | a, A, e, E, f, F, g, G |
109 | Matches a floating-point number in the style of strtod(3). The next pointer must be a pointer to float |
110 | (unless l or L is specified.) |
111 | |
112 | s Matches a sequence of non-white-space characters; the next pointer must be a pointer to char, and the array |
113 | |
114 | ... |
>Es liegt mit Sicherheit daran, dass du kein Buch hast, sondern versuchst >C nach der Methode 'Trial and Error' zu lernen. Warum gleich immer so böse. Sorry, natürlich meinte ich sscanf, mir ist bloß im Eifer des Gefechts sprintf rausgerutscht. Naja wie auch immer, ich habe es jetzt auf eine andere Art und Weise erledigt.
icke schrieb: >>Es liegt mit Sicherheit daran, dass du kein Buch hast, sondern versuchst >>C nach der Methode 'Trial and Error' zu lernen. > > Warum gleich immer so böse. Sorry, natürlich meinte ich sscanf, selbst wenn ich mir statt dem sprintf einen sscanf denke, ist da dann immer noch ein Fehler, der in jedem Buch ad nauseam durchgekaut wird.
1 | float fVar = 0; |
2 | int iVar = 0; |
3 | |
4 | sscanf( fVar, "%f", &text ); |
5 | fVar *= 10; |
6 | iVar = (int)fVar; |
7 | printf( "Wert: %d", iVar ); |
Und dann wird wohl noch die Floating Point Lib notwendig sein. Warum gleich immer so böse? Weil wir genau diesen Fall, kein Buch und kein Grundlagenwissen, mitlerweile hunderte male am Tag haben (ok. hundert sind übertrieben, aber bei >10 halten wir an gut besuchten Tagen). Die Subkultur: "ich will zwar alles, wills aber nicht lernen" nimmt überhand. Vielleicht sollte das Forum eine Casting-Show veranstalten
> Die Subkultur: "ich will zwar alles, wills aber nicht lernen" > nimmt überhand. > Vielleicht sollte das Forum eine Casting-Show veranstalten. Ja, aber wie nennen wir die dann? DFSDSLR? (übliche Reihenfolge, F = Forum und LR = Lernresistenten)
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