printf("Enter age and weight separated by spaces:\n");
'printf()' is a function defined in the ANSI library, for formatted output to the STANDARD OUTPUT device - usually the screen. (On UNIX systems, printf() output can be redirected to a file, and this is simulated in TC using the ccommand() library function.)
printf() accepts a character string (actually an array of char variables) as its first argument, optionally followed by additional arguments. The escape sequence '\n' in the character string tells C to begin a new line following this output.
Notice that all function calls in C are expressions which represent a value (or void). In fact, printf() returns the number of characters successfully printed, but we are ignoring this value here.
If a function is used in a C source file, the compiler requires either a declaration or a definition of the function in the source file as well. The declaration for printf() is contained in the file stdio.h, which was #included into this file via the preprocessor*.
