When to use vsnprintf?

The vsnprintf() function in C++ is used to write a formatted string to a string buffer. The vsnprint() function was introduced in C++ 11. Unlike vsprintf(), the maximum number of characters that can be written to the buffer is specified in vsnprintf() .

What does vsnprintf do?

The vsnprintf() function converts each entry in the argument list according to the corresponding format specifier in format. The format has the same form and function as the format string for the printf() function.

What does vsnprintf return?

The vsnprintf function returns the number of characters that are written, not counting the terminating null character. If count is zero and buffer is NULL , the value returned is the number of characters the functions would write. The value does not take into account a terminating NULL .

What is Vsprintf?

The vsprintf() function writes a formatted string to a variable. Unlike sprintf(), the arguments in vsprintf(), are placed in an array. The array elements will be inserted at the percent (%) signs in the main string. Tip: Related functions: fprintf(), vfprintf(), printf(), sprintf() and vprintf().

What is the difference between printf and sprintf?

The printf function formats and writes output to the standard output stream, stdout . The sprintf function formats and stores a series of characters and values in the array pointed to by buffer.

Where is snprintf defined?

snprintf() in C library The snprintf() function with the addition of the n argument, which indicates the maximum number of characters (including at the end of null character) to be written to buffer. It is defined in h> header file.

What is Va_start?

The C library macro void va_start(va_list ap, last_arg) initializes ap variable to be used with the va_arg and va_end macros. The last_arg is the last known fixed argument being passed to the function i.e. the argument before the ellipsis. This macro must be called before using va_arg and va_end.

What is argument list C++?

In these cases, C++ provides type checking only for the explicitly declared arguments. You can use variable argument lists when you need to make a function so general that even the number and types of arguments can vary. The family of functions is an example of functions that use variable argument lists.

What does vsnprintf ( ) do in C + + 11?

The vsnprintf () function in C++ is used to write a formatted string to a string buffer. The vsnprint () function was introduced in C++ 11. Unlike vsprintf (), the maximum number of characters that can be written to the buffer is specified in vsnprintf ().

What is the declaration for vsprintf ( ) in C?

Following is the declaration for vsprintf () function. str − This is the array of char elements where the resulting string is to be stored. format − This is the C string that contains the text to be written to the str.

How is snprintf similar to sprintf in C?

snprintf is extremely similar to sprintf, which can be found on the same manpage. After all, the names of the functions only differ by the character ‘n’! This is actually a pretty common convention in C: the function with the ‘n’ will require an upper bound or maximum size as an argument.

How does snprintf return the size of the format string?

Now that we understand how the format string and the size argument influence where snprintf places the null character, we can now discuss the return value of snprintf and its usefulness. snprintf returns the size of the format string after substitution.