PRINTF(3) Linux Programmer's Manual PRINTF(3)
NAME
printf, fprintf, sprintf, snprintf, vprintf, vfprintf, vsprintf, vsnprintf - formatted output conversion
SYNOPSIS
#include <stdio.h>
int printf(const char *format, ...);
int fprintf(FILE *stream, const char *format, ...);
int sprintf(char *str, const char *format, ...);
int snprintf(char *str, size_t size, const char *format, ...);
#include <stdarg.h>
int vprintf(const char *format, va_list ap);
int vfprintf(FILE *stream, const char *format, va_list ap);
int vsprintf(char *str, const char *format, va_list ap);
int vsnprintf(char *str, size_t size, const char *format, va_list ap);
DESCRIPTION
The functions in the printf family produce output according to a format as described below. The functions printf and vprintf write output
to stdout, the standard output stream; fprintf and vfprintf write output to the given output stream; sprintf, snprintf, vsprintf and
vsnprintf write to the character string str.
The functions vprintf, vfprintf, vsprintf, vsnprintf are equivalent to the functions printf, fprintf, sprintf, snprintf, respectively,
except that they are called with a va_list instead of a variable number of arguments. These functions do not call the va_end macro. Conse-
quently, the value of ap is undefined after the call. The application should call va_end(ap) itself afterwards.
These eight functions write the output under the control of a format string that specifies how subsequent arguments (or arguments accessed
via the variable-length argument facilities of stdarg(3)) are converted for output.
Return value
Upon successful return, these functions return the number of characters printed (not including the trailing '