Standard C++ Library Reference ISO/IEC (VERSION3)

perror
void perror(const char *s);
The function writes a line of text to the stream stderr. If s is not a null pointer, the function
first writes the C string s (as if by calling fputs(s, stderr)), followed by a colon (:) and
a space. It then writes the same message C string that is returned by strerror(errno),
converting the value stored in errno, followed by an NL.
printf
int printf(const char *format, ...);
The function generates formatted text, under the control of the format format and any
additional arguments, and writes each generated character to the stream stdout. It returns the
number of characters generated, or it returns a negative value if the function sets the error
indicator for the stream.
putc
int putc(int c, FILE *stream);
The function has the same effect as fputc(c, stream) except that a macro version of
putc can evaluate stream more than once.
putchar
int putchar(int c);
The function has the same effect as fputc(c, stdout), writing a character to the stream
stdout.
puts
int puts(const char *s);
The function accesses characters from the C string s and writes them to the stream stdout.
The function writes an NL character to the stream in place of the terminating null character. It
returns a nonnegative value if it has not set the error indicator; otherwise, it returns EOF.