Standard library header <cstdio>

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Standard library headers
Language support
Concepts
<concepts> (C++20)
Diagnostics
<system_error> (C++11)

Memory management
<memory_resource> (C++17)  
Metaprogramming
<type_traits> (C++11)
<ratio> (C++11)
General utilities
<utility>
<tuple> (C++11)
<optional> (C++17)
<variant> (C++17)
<any> (C++17)
<expected> (C++23)
<bitset>

<charconv> (C++17)
<format> (C++20)
<bit> (C++20)

Strings
<cuchar> (C++11)

Containers
<flat_set> (C++23)
<span> (C++20)
<mdspan> (C++23)

Iterators
<iterator>
Ranges
<ranges> (C++20)
<generator> (C++23)
Algorithms
Numerics
<cfenv> (C++11)
<complex>
<numbers> (C++20)

Time
<chrono> (C++11)
Localization
<codecvt> (C++11/17*)
Input/output
<filesystem> (C++17)
<cstdio>
<cinttypes> (C++11)
<strstream> (C++98*)
Regular expressions
<regex> (C++11)
Concurrency support
<stop_token> (C++20)
<thread> (C++11)
<atomic> (C++11)
<stdatomic.h> (C++23)
<mutex> (C++11)
<shared_mutex> (C++14)
<condition_variable> (C++11)  
<semaphore> (C++20)
<latch> (C++20)
<barrier> (C++20)
<future> (C++11)

C compatibility
<cstdbool> (C++11/17/20*)  
<ccomplex> (C++11/17/20*)
<ctgmath> (C++11/17/20*)

<cstdalign> (C++11/17/20*)

<ciso646> (until C++20)

 

This header was originally in the C standard library as <stdio.h>.

This header is part of the C-style input/output library.

Types

object type, capable of holding all information needed to control a C I/O stream
(typedef)
complete non-array object type, capable of uniquely specifying a position in a file, including its multibyte parse state
(typedef)
unsigned integer type returned by the sizeof operator
(typedef)

Macros

implementation-defined null pointer constant
(macro constant)
expression of type FILE* associated with the input stream
expression of type FILE* associated with the output stream
expression of type FILE* associated with the error output stream
(macro constant)
EOF
integer constant expression of type int and negative value
(macro constant)
FOPEN_MAX
number of files that can be open simultaneously
(macro constant)
FILENAME_MAX
size needed for an array of char to hold the longest supported file name
(macro constant)
BUFSIZ
size of the buffer used by std::setbuf
(macro constant)
_IOFBF_IOLBF_IONBF
argument to std::setbuf indicating fully buffered I/O
argument to std::setbuf indicating line buffered I/O
argument to std::setbuf indicating unbuffered I/O
(macro constant)
SEEK_SETSEEK_CURSEEK_END
argument to std::fseek indicating seeking from beginning of the file
argument to std::fseek indicating seeking from the current file position
argument to std::fseek indicating seeking from end of the file
(macro constant)
TMP_MAX
maximum number of unique filenames that can be generated by std::tmpnam
(macro constant)
L_tmpnam
size needed for an array of char to hold the result of std::tmpnam
(macro constant)

Functions

File access
opens a file
(function)
open an existing stream with a different name
(function)
closes a file
(function)
synchronizes an output stream with the actual file
(function)
sets the buffer for a file stream
(function)
sets the buffer and its size for a file stream
(function)
Direct input/output
reads from a file
(function)
writes to a file
(function)
Unformatted input/output
Narrow character
gets a character from a file stream
(function)
gets a character string from a file stream
(function)
writes a character to a file stream
(function)
writes a character string to a file stream
(function)
reads a character from stdin
(function)
(deprecated in C++11)(removed in C++14)
reads a character string from stdin
(function)
writes a character to stdout
(function)
writes a character string to stdout
(function)
puts a character back into a file stream
(function)
Formatted input/output
Narrow/multibyte character
reads formatted input from stdin, a file stream or a buffer
(function)
(C++11)(C++11)(C++11)
reads formatted input from stdin, a file stream or a buffer
using variable argument list
(function)
prints formatted output to stdout, a file stream or a buffer
(function)
prints formatted output to stdout, a file stream or a buffer
using variable argument list
(function)
File positioning
returns the current file position indicator
(function)
gets the file position indicator
(function)
moves the file position indicator to a specific location in a file
(function)
moves the file position indicator to a specific location in a file
(function)
moves the file position indicator to the beginning in a file
(function)
Error handling
clears errors
(function)
checks for the end-of-file
(function)
checks for a file error
(function)
displays a character string corresponding of the current error to stderr
(function)
Operations on files
erases a file
(function)
renames a file
(function)
creates and opens a temporary, auto-removing file
(function)
returns a unique filename
(function)

Synopsis

namespace std {
  using size_t = /* see description */;
  using FILE = /* see description */;
  using fpos_t = /* see description */;
}
 
#define NULL /* see description */
#define _IOFBF /* see description */
#define _IOLBF /* see description */
#define _IONBF /* see description */
#define BUFSIZ /* see description */
#define EOF /* see description */
#define FOPEN_MAX /* see description */
#define FILENAME_MAX /* see description */
#define L_tmpnam /* see description */
#define SEEK_CUR /* see description */
#define SEEK_END /* see description */
#define SEEK_SET /* see description */
#define TMP_MAX /* see description */
#define stderr /* see description */
#define stdin /* see description */
#define stdout /* see description */
 
namespace std {
  int remove(const char* filename);
  int rename(const char* old_p, const char* new_p);
  FILE* tmpfile();
  char* tmpnam(char* s);
  int fclose(FILE* stream);
  int fflush(FILE* stream);
  FILE* fopen(const char* filename, const char* mode);
  FILE* freopen(const char* filename, const char* mode, FILE* stream);
  void setbuf(FILE* stream, char* buf);
  int setvbuf(FILE* stream, char* buf, int mode, size_t size);
  int fprintf(FILE* stream, const char* format, ...);
  int fscanf(FILE* stream, const char* format, ...);
  int printf(const char* format, ...);
  int scanf(const char* format, ...);
  int snprintf(char* s, size_t n, const char* format, ...);
  int sprintf(char* s, const char* format, ...);
  int sscanf(const char* s, const char* format, ...);
  int vfprintf(FILE* stream, const char* format, va_list arg);
  int vfscanf(FILE* stream, const char* format, va_list arg);
  int vprintf(const char* format, va_list arg);
  int vscanf(const char* format, va_list arg);
  int vsnprintf(char* s, size_t n, const char* format, va_list arg);
  int vsprintf(char* s, const char* format, va_list arg);
  int vsscanf(const char* s, const char* format, va_list arg);
  int fgetc(FILE* stream);
  char* fgets(char* s, int n, FILE* stream);
  int fputc(int c, FILE* stream);
  int fputs(const char* s, FILE* stream);
  int getc(FILE* stream);
  int getchar();
  int putc(int c, FILE* stream);
  int putchar(int c);
  int puts(const char* s);
  int ungetc(int c, FILE* stream);
  size_t fread(void* ptr, size_t size, size_t nmemb, FILE* stream);
  size_t fwrite(const void* ptr, size_t size, size_t nmemb, FILE* stream);
  int fgetpos(FILE* stream, fpos_t* pos);
  int fseek(FILE* stream, long int offset, int whence);
  int fsetpos(FILE* stream, const fpos_t* pos);
  long int ftell(FILE* stream);
  void rewind(FILE* stream);
  void clearerr(FILE* stream);
  int feof(FILE* stream);
  int ferror(FILE* stream);
  void perror(const char* s);
}

Notes