计算机中stdio.h是什么意思有什么作用
#include是在程序编译之前要处理的内容,称为编译预处理命令。编译预处理命令还有很多,它们都以“#”开头,并且不用分号结尾。
stdio.h是头文件,标准输入输出函数库。头文件是扩展名为 .h 的文件,包含了 C 函数声明和宏定义,被多个源文件中引用共享。
有两种类型的头文件:程序员编写的头文件和编译器自带的头文件。
在程序中要使用头文件,需要使用 C 预处理指令 #include 来引用它。 stdio.h 头文件,它是编译器自带的头文件。
引用头文件相当于复制头文件的内容,但是我们不会直接在源文件中复制头文件的内容,因为这么做很容易出错,特别在程序是由多个源文件组成的时候。
扩展资料
程序设计语言的预处理的概念:在编译之前进行的处理。 C语言的预处理主要有三个方面的内容:宏定义;文件包含;条件编译。 预处理命令以符号“#”开头。
头文件的内容除了函数原型和宏定义外,还可以有结构体定义,全局变量定义:
一个#include命令指定一个头文件;
文件1包含文件2,文件2用到文件3,则文件3的包含命令#include应放在文件1的头部第一行;
包含可以嵌套;
称为标准方式,系统到头文件目录查找文件,"文件名"则先在当前目录查找,而后到头文件目录查找;
被包含文件中的静态全局变量不用在包含文件中声明。
参考资料来源:百度百科-预处理命令
参考资料来源:百度百科-头文件
#只是符号,表示预定义
引用stdio.h,则可以使用里面定义的方法、常量等资源
意思就是说标准输入输出头文件!
所以了,用到标准输入输出函数时,就要调用这个头文件!
原程序为:
/*
* stdio.h
* This file has no copyright assigned and is placed in the Public Domain.
* This file is a part of the mingw-runtime package.
* No warranty is given; refer to the file DISCLAIMER within the package.
*
* Definitions of types and prototypes of functions for standard input and
* output.
*
* NOTE: The file manipulation functions provided by Microsoft seem to
* work with either slash (/) or backslash (\) as the directory separator.
*
*/
#ifndef _STDIO_H_
#define _STDIO_H_
/* All the headers include this file. */
#include <_mingw.h>
#ifndef RC_INVOKED
#define __need_size_t
#define __need_NULL
#define __need_wchar_t
#define __need_wint_t
#include <stddef.h>
#define __need___va_list
#include <stdarg.h>
#endif /* Not RC_INVOKED */
/* Flags for the iobuf structure */
#define _IOREAD 1 /* currently reading */
#define _IOWRT 2 /* currently writing */
#define _IORW 0x0080 /* opened as "r+w" */
/*
* The three standard file pointers provided by the run time library.
* NOTE: These will go to the bit-bucket silently in GUI applications!
*/
#define STDIN_FILENO 0
#define STDOUT_FILENO 1
#define STDERR_FILENO 2
/* Returned by various functions on end of file condition or error. */
#define EOF (-1)
/*
* The maximum length of a file name. You should use GetVolumeInformation
* instead of this constant. But hey, this works.
* Also defined in io.h.
*/
#ifndef FILENAME_MAX
#define FILENAME_MAX (260)
#endif
/*
* The maximum number of files that may be open at once. I have set this to
* a conservative number. The actual value may be higher.
*/
#define FOPEN_MAX (20)
/* After creating this many names, tmpnam and tmpfile return NULL */
#define TMP_MAX 32767
/*
* Tmpnam, tmpfile and, sometimes, _tempnam try to create
* temp files in the root directory of the current drive
* (not in pwd, as suggested by some older MS doc's).
* Redefining these macros does not effect the CRT functions.
*/
#define _P_tmpdir "\\"
#ifndef __STRICT_ANSI__
#define P_tmpdir _P_tmpdir
#endif
#define _wP_tmpdir L"\\"
/*
* The maximum size of name (including NUL) that will be put in the user
* supplied buffer caName for tmpnam.
* Inferred from the size of the static buffer returned by tmpnam
* when passed a NULL argument. May actually be smaller.
*/
#define L_tmpnam (16)
#define _IOFBF 0x0000 /* full buffered */
#define _IOLBF 0x0040 /* line buffered */
#define _IONBF 0x0004 /* not buffered */
#define _IOMYBUF 0x0008 /* stdio malloc()'d buffer */
#define _IOEOF 0x0010 /* EOF reached on read */
#define _IOERR 0x0020 /* I/O error from system */
#define _IOSTRG 0x0040 /* Strange or no file descriptor */
#ifdef _POSIX_SOURCE
# define _IOAPPEND 0x0200
#endif
/*
* The buffer size as used by setbuf such that it is equivalent to
* (void) setvbuf(fileSetBuffer, caBuffer, _IOFBF, BUFSIZ).
*/
#define BUFSIZ 512
/* Constants for nOrigin indicating the position relative to which fseek
* sets the file position. Enclosed in ifdefs because io.h could also
* define them. (Though not anymore since io.h includes this file now.) */
#ifndef SEEK_SET
#define SEEK_SET (0)
#endif
#ifndef SEEK_CUR
#define SEEK_CUR (1)
#endif
#ifndef SEEK_END
#define SEEK_END (2)
#endif
#ifndef RC_INVOKED
#ifndef __VALIST
#ifdef __GNUC__
#define __VALIST __gnuc_va_list
#else
#define __VALIST char*
#endif
#endif /* defined __VALIST */
/*
* The structure underlying the FILE type.
*
* Some believe that nobody in their right mind should make use of the
* internals of this structure. Provided by Pedro A. Aranda Gutiirrez
* <paag@tid.es>.
*/
#ifndef _FILE_DEFINED
#define _FILE_DEFINED
typedef struct _iobuf
{
char* _ptr;
int _cnt;
char* _base;
int _flag;
int _file;
int _charbuf;
int _bufsiz;
char* _tmpfname;
} FILE;
#endif /* Not _FILE_DEFINED */
/*
* The standard file handles
*/
#ifndef __DECLSPEC_SUPPORTED
extern FILE (*_imp___iob)[]; /* A pointer to an array of FILE */
#define _iob (*_imp___iob) /* An array of FILE */
#else /* __DECLSPEC_SUPPORTED */
__MINGW_IMPORT FILE _iob[]; /* An array of FILE imported from DLL. */
#endif /* __DECLSPEC_SUPPORTED */
#define stdin (&_iob[STDIN_FILENO])
#define stdout (&_iob[STDOUT_FILENO])
#define stderr (&_iob[STDERR_FILENO])
#ifdef __cplusplus
extern "C" {
#endif
/*
* File Operations
*/
_CRTIMP FILE* __cdecl fopen (const char*, const char*);
_CRTIMP FILE* __cdecl freopen (const char*, const char*, FILE*);
_CRTIMP int __cdecl fflush (FILE*);
_CRTIMP int __cdecl fclose (FILE*);
/* MS puts remove & rename (but not wide versions) in io.h also */
_CRTIMP int __cdecl remove (const char*);
_CRTIMP int __cdecl rename (const char*, const char*);
_CRTIMP FILE* __cdecl tmpfile (void);
_CRTIMP char* __cdecl tmpnam (char*);
#ifndef __STRICT_ANSI__
_CRTIMP char* __cdecl _tempnam (const char*, const char*);
_CRTIMP int __cdecl _rmtmp(void);
#ifndef NO_OLDNAMES
_CRTIMP char* __cdecl tempnam (const char*, const char*);
_CRTIMP int __cdecl rmtmp(void);
#endif
#endif /* __STRICT_ANSI__ */
_CRTIMP int __cdecl setvbuf (FILE*, char*, int, size_t);
_CRTIMP void __cdecl setbuf (FILE*, char*);
/*
* Formatted Output
*/
_CRTIMP int __cdecl fprintf (FILE*, const char*, ...);
_CRTIMP int __cdecl printf (const char*, ...);
_CRTIMP int __cdecl sprintf (char*, const char*, ...);
_CRTIMP int __cdecl _snprintf (char*, size_t, const char*, ...);
_CRTIMP int __cdecl vfprintf (FILE*, const char*, __VALIST);
_CRTIMP int __cdecl vprintf (const char*, __VALIST);
_CRTIMP int __cdecl vsprintf (char*, const char*, __VALIST);
_CRTIMP int __cdecl _vsnprintf (char*, size_t, const char*, __VALIST);
#ifndef __NO_ISOCEXT /* externs in libmingwex.a */
int __cdecl snprintf(char* s, size_t n, const char* format, ...);
__CRT_INLINE int __cdecl
vsnprintf (char* s, size_t n, const char* format, __VALIST arg)
{ return _vsnprintf ( s, n, format, arg); }
int __cdecl vscanf (const char * __restrict__, __VALIST);
int __cdecl vfscanf (FILE * __restrict__, const char * __restrict__,
__VALIST);
int __cdecl vsscanf (const char * __restrict__,
const char * __restrict__, __VALIST);
#endif
/*
* Formatted Input
*/
_CRTIMP int __cdecl fscanf (FILE*, const char*, ...);
_CRTIMP int __cdecl scanf (const char*, ...);
_CRTIMP int __cdecl sscanf (const char*, const char*, ...);
/*
* Character Input and Output Functions
*/
_CRTIMP int __cdecl fgetc (FILE*);
_CRTIMP char* __cdecl fgets (char*, int, FILE*);
_CRTIMP int __cdecl fputc (int, FILE*);
_CRTIMP int __cdecl fputs (const char*, FILE*);
_CRTIMP char* __cdecl gets (char*);
_CRTIMP int __cdecl puts (const char*);
_CRTIMP int __cdecl ungetc (int, FILE*);
/* Traditionally, getc and putc are defined as macros. but the
standard doesn't say that they must be macros.
We use inline functions here to allow the fast versions
to be used in C++ with namespace qualification, eg., ::getc.
_filbuf and _flsbuf are not thread-safe. */
_CRTIMP int __cdecl _filbuf (FILE*);
_CRTIMP int __cdecl _flsbuf (int, FILE*);
#if !defined _MT
__CRT_INLINE int __cdecl getc (FILE* __F)
{
return (--__F->_cnt >= 0)
? (int) (unsigned char) *__F->_ptr++
: _filbuf (__F);
}
__CRT_INLINE int __cdecl putc (int __c, FILE* __F)
{
return (--__F->_cnt >= 0)
? (int) (unsigned char) (*__F->_ptr++ = (char)__c)
: _flsbuf (__c, __F);
}
__CRT_INLINE int __cdecl getchar (void)
{
return (--stdin->_cnt >= 0)
? (int) (unsigned char) *stdin->_ptr++
: _filbuf (stdin);
}
__CRT_INLINE int __cdecl putchar(int __c)
{
return (--stdout->_cnt >= 0)
? (int) (unsigned char) (*stdout->_ptr++ = (char)__c)
: _flsbuf (__c, stdout);}
#else /* Use library functions. */
_CRTIMP int __cdecl getc (FILE*);
_CRTIMP int __cdecl putc (int, FILE*);
_CRTIMP int __cdecl getchar (void);
_CRTIMP int __cdecl putchar (int);
#endif
/*
* Direct Input and Output Functions
*/
_CRTIMP size_t __cdecl fread (void*, size_t, size_t, FILE*);
_CRTIMP size_t __cdecl fwrite (const void*, size_t, size_t, FILE*);
/*
* File Positioning Functions
*/
_CRTIMP int __cdecl fseek (FILE*, long, int);
_CRTIMP long __cdecl ftell (FILE*);
_CRTIMP void __cdecl rewind (FILE*);
#ifdef __USE_MINGW_FSEEK /* These are in libmingwex.a */
/*
* Workaround for limitations on win9x where a file contents are
* not zero'd out if you seek past the end and then write.
*/
int __cdecl __mingw_fseek (FILE *, long, int);
int __cdecl __mingw_fwrite (const void*, size_t, size_t, FILE*);
#define fseek(fp, offset, whence) __mingw_fseek(fp, offset, whence)
#define fwrite(buffer, size, count, fp) __mingw_fwrite(buffer, size, count, fp)
#endif /* __USE_MINGW_FSEEK */
/*
* An opaque data type used for storing file positions... The contents of
* this type are unknown, but we (the compiler) need to know the size
* because the programmer using fgetpos and fsetpos will be setting aside
* storage for fpos_t structres. Actually I tested using a byte array and
* it is fairly evident that the fpos_t type is a long (in CRTDLL.DLL).
* Perhaps an unsigned long? TODO? It's definitely a 64-bit number in
* MSVCRT however, and for now `long long' will do.
*/
#ifdef __MSVCRT__
typedef long long fpos_t;
#else
typedef long fpos_t;
#endif
_CRTIMP int __cdecl fgetpos (FILE*, fpos_t*);
_CRTIMP int __cdecl fsetpos (FILE*, const fpos_t*);
/*
* Error Functions
*/
_CRTIMP int __cdecl feof (FILE*);
_CRTIMP int __cdecl ferror (FILE*);
#ifdef __cplusplus
inline int __cdecl feof (FILE* __F)
{ return __F->_flag & _IOEOF; }
inline int __cdecl ferror (FILE* __F)
{ return __F->_flag & _IOERR; }
#else
#define feof(__F) ((__F)->_flag & _IOEOF)
#define ferror(__F) ((__F)->_flag & _IOERR)
#endif
_CRTIMP void __cdecl clearerr (FILE*);
_CRTIMP void __cdecl perror (const char*);
#ifndef __STRICT_ANSI__
/*
* Pipes
*/
_CRTIMP FILE* __cdecl _popen (const char*, const char*);
_CRTIMP int __cdecl _pclose (FILE*);
#ifndef NO_OLDNAMES
_CRTIMP FILE* __cdecl popen (const char*, const char*);
_CRTIMP int __cdecl pclose (FILE*);
#endif
/*
* Other Non ANSI functions
*/
_CRTIMP int __cdecl _flushall (void);
_CRTIMP int __cdecl _fgetchar (void);
_CRTIMP int __cdecl _fputchar (int);
_CRTIMP FILE* __cdecl _fdopen (int, const char*);
_CRTIMP int __cdecl _fileno (FILE*);
_CRTIMP int __cdecl _fcloseall(void);
_CRTIMP FILE* __cdecl _fsopen(const char*, const char*, int);
#ifdef __MSVCRT__
_CRTIMP int __cdecl _getmaxstdio(void);
_CRTIMP int __cdecl _setmaxstdio(int);
#endif
#ifndef _NO_OLDNAMES
_CRTIMP int __cdecl fgetchar (void);
_CRTIMP int __cdecl fputchar (int);
_CRTIMP FILE* __cdecl fdopen (int, const char*);
_CRTIMP int __cdecl fileno (FILE*);
#endif /* Not _NO_OLDNAMES */
#define _fileno(__F) ((__F)->_file)
#ifndef _NO_OLDNAMES
#define fileno(__F) ((__F)->_file)
#endif
#if defined (__MSVCRT__) && !defined (__NO_MINGW_LFS)
#include <sys/types.h>
__CRT_INLINE FILE* __cdecl fopen64 (const char* filename, const char* mode)
{
return fopen (filename, mode);
}
int __cdecl fseeko64 (FILE*, off64_t, int);
#ifdef __USE_MINGW_FSEEK
int __cdecl __mingw_fseeko64 (FILE *, off64_t, int);
#define fseeko64(fp, offset, whence) __mingw_fseeko64(fp, offset, whence)
#endif
__CRT_INLINE off64_t __cdecl ftello64 (FILE * stream)
{
fpos_t pos;
if (fgetpos(stream, &pos))
return -1LL;
else
return ((off64_t) pos);
}
#endif /* __NO_MINGW_LFS */
#endif /* Not __STRICT_ANSI__ */
/* Wide versions */
#ifndef _WSTDIO_DEFINED
/* also in wchar.h - keep in sync */
_CRTIMP int __cdecl fwprintf (FILE*, const wchar_t*, ...);
_CRTIMP int __cdecl wprintf (const wchar_t*, ...);
_CRTIMP int __cdecl swprintf (wchar_t*, const wchar_t*, ...);
_CRTIMP int __cdecl _snwprintf (wchar_t*, size_t, const wchar_t*, ...);
_CRTIMP int __cdecl vfwprintf (FILE*, const wchar_t*, __VALIST);
_CRTIMP int __cdecl vwprintf (const wchar_t*, __VALIST);
_CRTIMP int __cdecl vswprintf (wchar_t*, const wchar_t*, __VALIST);
_CRTIMP int __cdecl _vsnwprintf (wchar_t*, size_t, const wchar_t*, __VALIST);
_CRTIMP int __cdecl fwscanf (FILE*, const wchar_t*, ...);
_CRTIMP int __cdecl wscanf (const wchar_t*, ...);
_CRTIMP int __cdecl swscanf (const wchar_t*, const wchar_t*, ...);
_CRTIMP wint_t __cdecl fgetwc (FILE*);
_CRTIMP wint_t __cdecl fputwc (wchar_t, FILE*);
_CRTIMP wint_t __cdecl ungetwc (wchar_t, FILE*);
#ifdef __MSVCRT__
_CRTIMP wchar_t* __cdecl fgetws (wchar_t*, int, FILE*);
_CRTIMP int __cdecl fputws (const wchar_t*, FILE*);
_CRTIMP wint_t __cdecl getwc (FILE*);
_CRTIMP wint_t __cdecl getwchar (void);
_CRTIMP wchar_t* __cdecl _getws (wchar_t*);
_CRTIMP wint_t __cdecl putwc (wint_t, FILE*);
_CRTIMP int __cdecl _putws (const wchar_t*);
_CRTIMP wint_t __cdecl putwchar (wint_t);
_CRTIMP FILE* __cdecl _wfdopen(int, wchar_t *);
_CRTIMP FILE* __cdecl _wfopen (const wchar_t*, const wchar_t*);
_CRTIMP FILE* __cdecl _wfreopen (const wchar_t*, const wchar_t*, FILE*);
_CRTIMP FILE* __cdecl _wfsopen (const wchar_t*, const wchar_t*, int);
_CRTIMP wchar_t* __cdecl _wtmpnam (wchar_t*);
_CRTIMP wchar_t* __cdecl _wtempnam (const wchar_t*, const wchar_t*);
_CRTIMP int __cdecl _wrename (const wchar_t*, const wchar_t*);
_CRTIMP int __cdecl _wremove (const wchar_t*);
_CRTIMP void __cdecl _wperror (const wchar_t*);
_CRTIMP FILE* __cdecl _wpopen (const wchar_t*, const wchar_t*);
#endif /* __MSVCRT__ */
#ifndef __NO_ISOCEXT /* externs in libmingwex.a */
int __cdecl snwprintf (wchar_t* s, size_t n, const wchar_t* format, ...);
__CRT_INLINE int __cdecl
vsnwprintf (wchar_t* s, size_t n, const wchar_t* format, __VALIST arg)
{ return _vsnwprintf ( s, n, format, arg);}
int __cdecl vwscanf (const wchar_t * __restrict__, __VALIST);
int __cdecl vfwscanf (FILE * __restrict__,
const wchar_t * __restrict__, __VALIST);
int __cdecl vswscanf (const wchar_t * __restrict__,
const wchar_t * __restrict__, __VALIST);
#endif
#define _WSTDIO_DEFINED
#endif /* _WSTDIO_DEFINED */
#ifndef __STRICT_ANSI__
#ifdef __MSVCRT__
#ifndef NO_OLDNAMES
_CRTIMP FILE* __cdecl wpopen (const wchar_t*, const wchar_t*);
#endif /* not NO_OLDNAMES */
#endif /* MSVCRT runtime */
/*
* Other Non ANSI wide functions
*/
_CRTIMP wint_t __cdecl _fgetwchar (void);
_CRTIMP wint_t __cdecl _fputwchar (wint_t);
_CRTIMP int __cdecl _getw (FILE*);
_CRTIMP int __cdecl _putw (int, FILE*);
#ifndef _NO_OLDNAMES
_CRTIMP wint_t __cdecl fgetwchar (void);
_CRTIMP wint_t __cdecl fputwchar (wint_t);
_CRTIMP int __cdecl getw (FILE*);
_CRTIMP int __cdecl putw (int, FILE*);
#endif /* Not _NO_OLDNAMES */
#endif /* __STRICT_ANSI */
#ifdef __cplusplus
}
#endif
#endif /* Not RC_INVOKED */
#endif /* _STDIO_H_ */
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如何用c语言计算小数点后位数
具体实现可参考:include <stdio.h>#include <stdlib.h>#include <string.h>int main(int argc, char* argv[]){ char a[128]; while(scanf("%s",a)!=EOF) { if(strstr(a,".")!=NULL) printf("%d\\n",strlen(strstr(a,".")+1)); else printf("0\\n"); ...
解饺正安: stdio.h是标准输入输出的头文件,i代表input,o代表output,而.h这是头文件的扩展名.代码写多了你自然会明白,如果是初学者,就不必要深究下去.你记住是头文件就是了
麻栗坡县18520524085: C语言中的编码预处理的命令<stdio.h>是什么意思! - ?
解饺正安: stdio.h就是指“standard input&output" 意思就是说标准输入输出头文件! 所以了,用到标准输入输出函数时,就要调用这个头文件! 这个头文件中所声明关于标准输入输出的常用函数列表如下: 函数名 函数原型 具体功能 scanf int scanf(...
麻栗坡县18520524085: c语言中的#include<stdio.h>是什么意思 - ?
解饺正安: 头文件名,扩展名为.h的文件就是头文件. stdio.h是输入输出流函数的头文件,包含了一系列输入输出的函数,你必须在程序的开头调用它#include,才能使用它所包含的函数.
麻栗坡县18520524085: stdio.h里面的是什么意思 - ?
解饺正安: stdio.h,头文件,包含stdio.h头文件的意思 是库函数,标准输入输出函数 include 称为文件包含命令,其意义是把尖括号""或引号<>内指定的文件包含到本程序中,成为本程序的一部分.被包含的文件通常是由系统提供的,其扩展名为.h 而...
麻栗坡县18520524085: c语言中#include <stdio.h>是什么意思 - ?
解饺正安: 包含标准头文件stdio.h. 1、#include 是C语言预编译命令之一. include并不属于C语言关键字.以#开头的#include是预编译命令,即不是在运行过程中生效,而是在编译的时候就会生效. include的效果为,在编译时把被包含的文件中的内容,放到被编译的c文件对应位置. 2、stdio.h是C语言库文件的头文件之一,包含了常用的标准输入输出. 比如printf,scanf等语句都是在stdio.h中的. 3、在源文件中包含了stdio.h 就等于声明了stdio.h中的所有函数,并使该文件中的所有宏定义在源文件中可用. 即使用printf,scanf等语句不会引起警告, 同时可以使用诸如NULL一类的宏定义.
麻栗坡县18520524085: 电脑上的#include <stdio.h>是什么意思?
解饺正安: 在使用标准输入输出函数时要调用标准输入输出头文件, stdio.h =standard input&output
麻栗坡县18520524085: C语言中每个程序前都有 #include "stdio.h" 是什么意思? - ?
解饺正安: stdio.h是C编译系统提供的一个文件名,stdio是“standard input & output”的缩写,即有关标准输入输出的信息.在程序中用到系统提供的标准函数库中的输入输出函数时,应在程序的开头写上#include.若用不到系统提供的标准函数库中的输入输出函数,声部声明也无所谓.
麻栗坡县18520524085: 在C语言中 头文件stdio.h加引号"stdio.h"是什么意思 - ?
解饺正安: Stdio.h是标准输入输出头文件,里面包含了标准输入输出函数的声明, printf就是其中的一个, 如果程序不使用输入输出功能可以不包含此头文件,但是这种情况很少,一般C程序都会包含此头文件.一般情况下 系统自带头文件就用<> 自己写的头文件就用""
麻栗坡县18520524085: c语言中#include〈stdio.h〉是能够输入输出的意思?在程序中才能输入或者输出一个数? - ?
解饺正安: #include 是编译预处理命令 stdio 是 standard input & output"(标准输入输出).h 是头文件 输入输出函数被定义在这个头文件里面了,只有包含这个头文件才能进行输入输出.
麻栗坡县18520524085: 编程中 #include <stdio.h> 是什么意思? - ?
解饺正安: 头文件,包含stdio.h头文件的意思include 称为文件包含命令,其意义是把尖括号""或引号<>内指定的文件包含到本程序中,成为本程序的一部分.被包含的文件通常是由系统提供的,其扩展名为.h 而stdio为standard input output的缩写,意为...