Differenze tra le versioni di "Getline ()"
Da Gambas-it.org - Wikipedia.
(Creata pagina con "La funzione '''getline()''', dichiarata nel file header "stdio.h" come segue: _IO_ssize_t getline (char **__restrict __lineptr, size_t *__restrict __n, FILE *__restrict __str...") |
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| Riga 12: | Riga 12: | ||
Library "libc:6" | Library "libc:6" | ||
| − | <FONT Color=gray>FILE *fopen (const char *__restrict __filename, const char *__restrict __modes)'' | + | <FONT Color=gray>' ''FILE *fopen (const char *__restrict __filename, const char *__restrict __modes)'' |
' ''Open a file and create a new stream for it.''</font> | ' ''Open a file and create a new stream for it.''</font> | ||
Private Extern fopen(__filename As String, __modes As String) As Pointer | Private Extern fopen(__filename As String, __modes As String) As Pointer | ||
| − | <FONT Color=gray>_IO_ssize_t getline (char **__restrict __lineptr, size_t *__restrict __n, FILE *__restrict __stream)'' | + | <FONT Color=gray>' ''_IO_ssize_t getline (char **__restrict __lineptr, size_t *__restrict __n, FILE *__restrict __stream)'' |
' ''Read up to (and including) a newline from STREAM.''</font> | ' ''Read up to (and including) a newline from STREAM.''</font> | ||
Private Extern <FONT Color=#B22222>getline</font>(__lineptr As Pointer, __n As Pointer, __stream As Pointer) As Long | Private Extern <FONT Color=#B22222>getline</font>(__lineptr As Pointer, __n As Pointer, __stream As Pointer) As Long | ||
| − | <FONT Color=gray>int fclose (FILE *__stream)'' | + | <FONT Color=gray>' ''int fclose (FILE *__stream)'' |
' ''Close STREAM.''</font> | ' ''Close STREAM.''</font> | ||
Private Extern fclose(filestream As Pointer) As Integer | Private Extern fclose(filestream As Pointer) As Integer | ||
Versione delle 18:33, 4 apr 2018
La funzione getline(), dichiarata nel file header "stdio.h" come segue:
_IO_ssize_t getline (char **__restrict __lineptr, size_t *__restrict __n, FILE *__restrict __stream)
legge da un flusso di dati fino al valore "nuova linea a capo" (&h0A).
La funzione è, pertanto, utile per leggere una riga da un file (flusso) di testo.
Volendola utilizzare direttamente in Gambas, bisognerà dichiararla con Extern, nonché dichiarare la libreria di C: libc.so.6, nella quale la funzione è contenuta:
Private Extern getline(__lineptr As Pointer, __n As Pointer, __stream As Pointer) As Long
Mostriamo di seguito un semplice esempio, nel quale si leggerà un testo (anche eventualmente comprensivo di spazi) dallo standard input:
Library "libc:6"
' FILE *fopen (const char *__restrict __filename, const char *__restrict __modes)
' Open a file and create a new stream for it.
Private Extern fopen(__filename As String, __modes As String) As Pointer
' _IO_ssize_t getline (char **__restrict __lineptr, size_t *__restrict __n, FILE *__restrict __stream)
' Read up to (and including) a newline from STREAM.
Private Extern getline(__lineptr As Pointer, __n As Pointer, __stream As Pointer) As Long
' int fclose (FILE *__stream)
' Close STREAM.
Private Extern fclose(filestream As Pointer) As Integer
Public Sub Main()
Dim dest, p As Pointer
Dim l As Long
p = fopen("/dev/stdin", "r")
' Resta in attesa che si inserisca un qualsiasi testo nella console/Terminale, e si prema sul tasto "Invio":
getline(VarPtr(dest), VarPtr(l), p)
Print String@(dest)
fclose(p)
End
