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The formatting placeholders in scanf are more or less the same as that in printf, its reverse function.As in printf, the POSIX extension n$ is defined. [2]There are rarely constants (i.e., characters that are not formatting placeholders) in a format string, mainly because a program is usually not designed to read known data, although scanf does accept these if explicitly specified.
The <inttypes.h> header (cinttypes in C++) provides features that enhance the functionality of the types defined in the <stdint.h> header. It defines macros for printf format string and scanf format string specifiers corresponding to the types defined in <stdint.h> and several functions for working with the intmax_t and uintmax_t types.
The C programming language provides many standard library functions for file input and output.These functions make up the bulk of the C standard library header <stdio.h>. [1] The functionality descends from a "portable I/O package" written by Mike Lesk at Bell Labs in the early 1970s, [2] and officially became part of the Unix operating system in Version 7.
printf is a C function belonging to the ANSI C standard library, and included in the file stdio.h.Its purpose is to print formatted text to the standard output stream.Hence the "f" in the name stands for "formatted".
C functions are akin to the subroutines of Fortran or the procedures of Pascal. A definition is a special type of declaration. A variable definition sets aside storage and possibly initializes it, a function definition provides its body. An implementation of C providing all of the standard library functions is called a hosted implementation.
The C standard library, sometimes referred to as libc, [1] is the standard library for the C programming language, as specified in the ISO C standard. [2] Starting from the original ANSI C standard, it was developed at the same time as the C POSIX library, which is a superset of it. [3]
The functions alter the behavior of printf/scanf/strtod which are often used to write saved data to a file or to other programs. The result is that a saved file in one locale will not be readable in another locale, or not be readable at all due to assumptions such as "numbers end at comma characters".
C library functions like scanf can be used safely, but require the programmer to take care with the selection of safe format strings, by sanitizing it before using it. Encrypt/authenticate all important data transmitted over networks. Do not attempt to implement your own encryption scheme, use a proven one instead.