How do I use fprintf in Linux?
Table of Contents
How do I use fprintf in Linux?
format, input[j]); if (j == 0) { printf(“%s%s%s\n”, table[i]. format, convbuf, table[i]. description); } else { printf(“%s\n”, convbuf); } Printing Wide Characters The following example prints a series of wide characters.
How do I use Vsnprintf?
The vsnprintf() function in C++ is used to write a formatted string to a string buffer….vsnprintf() Parameters.
| Format Specifier | Description |
|---|---|
| c | Writes a single character |
| s | Writes a character string |
| d or i | Converts a signed integer to decimal representation |
| o | Converts an unsigned integer to octal representation |
What is Vsprintf?
The vsprintf() function is similar to sprintf(), except that arg_ptr points to a list of arguments whose number can vary from call to call in the program. In contrast, sprintf() can have a list of arguments, but the number of arguments in that list is fixed when you compile the program.
Why is Snprintf unsafe?
Warning: The sprintf function can be dangerous because it can potentially output more characters than can fit in the allocation size of the string s . Remember that the field width given in a conversion specification is only a minimum value. To avoid this problem, you can use snprintf or asprintf , described below.
What is Vfprintf in C?
The C library function int vfprintf(FILE *stream, const char *format, va_list arg) sends formatted output to a stream using an argument list passed to it.
Is Vsnprintf thread safe?
It’s not thread safe, since the buffer where you sprintf is shared between all threads.
What is a va_list?
va_list is a complete object type suitable for holding the information needed by the macros va_start, va_copy, va_arg, and va_end. If a va_list instance is created, passed to another function, and used via va_arg in that function, then any subsequent use in the calling function should be preceded by a call to va_end.
What is Va_start?
The va_start macro enables access to the variable arguments following the named argument parm_n . va_start should be invoked with an instance to a valid va_list object ap before any calls to va_arg.
What is the difference between sprintf and Snprintf?
The snprintf function is similar to sprintf , except that the size argument specifies the maximum number of characters to produce. The trailing null character is counted towards this limit, so you should allocate at least size characters for the string s .
Is Snprintf safer than sprintf?
Snprintf is more secure and if the string number overruns the characters, the string is protected in the buffer even if the format is different. It works with n characters and nth location and hence the location of null character is not considered at all. Allocation of null character memory is preserved in sprintf.
Is Vfprintf thread safe?
Anyways, vprintf() is a thread-safe function but it has a limitation that a read immediately following a write or a write immediately following a read there must be a flush work be done.
What is a Va_list?
How do you read and display strings?
You can use the fgets() function to read a line of string. And, you can use puts() to display the string.
Is Scanf thread safe?
the standard C printf() and scanf() functions use stdio so they are thread-safe.
Is Va_start thread safe?
As far as being serially-reentrant (ie., if foo() uses va_start is it safe for foo() to call bar() which also uses va_start ), the answer is that’s fine – as long as the va_list instance isn’t the same.
