1、头文件
#include <fcgi_stdio.h>
2、while(FCGI_Accept()>=0)//这里进入循环，前台每请求一次fcgi服务，就循环一次
循环内处理：
char *query_string=getenv("QUERY_STRING");
3、从获得的query_string解析查询字段，进行后续操作。
4、用printf返回处理结果给web服务器，再由web服务器将结果返回给客户端。
（这里的printf函数是在fcgi_stdio.h中重新定义了的）
附：fcgi_stdio.h
/*
* fcgi_stdio.h --
*
* FastCGI-stdio compatibility package
*
*
* Copyright (c) 1996 Open Market, Inc.
*
* See the file "LICENSE.TERMS" for information on usage and redistribution
* of this file, and for a DISCLAIMER OF ALL WARRANTIES.
*
* $Id: fcgi_stdio.h,v 1.5 2001/06/22 13:21:15 robs Exp $
*/
#ifndef _FCGI_STDIO
#define _FCGI_STDIO 1
#include <stdio.h>
#include <sys/types.h>
#include "fcgiapp.h"
#if defined (c_plusplus) || defined (__cplusplus)
extern "C" {
#endif
#ifndef DLLAPI
#ifdef _WIN32
#define DLLAPI __declspec(dllimport)
#else
#define DLLAPI
#endif
#endif
/*
* Wrapper type for FILE
*/
typedef struct {
FILE *stdio_stream;
FCGX_Stream *fcgx_stream;
} FCGI_FILE;
/*
* The four new functions and two new macros
*/
DLLAPI int FCGI_Accept(void);
DLLAPI void FCGI_Finish(void);
DLLAPI int FCGI_StartFilterData(void);
DLLAPI void FCGI_SetExitStatus(int status);
#define FCGI_ToFILE(fcgi_file) (fcgi_file->stdio_stream)
#define FCGI_ToFcgiStream(fcgi_file) (fcgi_file->fcgx_stream)
/*
* Wrapper stdin, stdout, and stderr variables, set up by FCGI_Accept()
*/
DLLAPI extern FCGI_FILE _fcgi_sF[];
#define FCGI_stdin (&_fcgi_sF[0])
#define FCGI_stdout (&_fcgi_sF[1])
#define FCGI_stderr (&_fcgi_sF[2])
/*
* Wrapper function prototypes, grouped according to sections
* of Harbison & Steele, "C: A Reference Manual," fourth edition,
* Prentice-Hall, 1995.
*/
DLLAPI void FCGI_perror(const char *str);
DLLAPI FCGI_FILE *FCGI_fopen(const char *path, const char *mode);
DLLAPI int FCGI_fclose(FCGI_FILE *fp);
DLLAPI int FCGI_fflush(FCGI_FILE *fp);
DLLAPI FCGI_FILE *FCGI_freopen(const char *path, const char *mode, FCGI_FILE *fp);
DLLAPI int FCGI_setvbuf(FCGI_FILE *fp, char *buf, int bufmode, size_t size);
DLLAPI void FCGI_setbuf(FCGI_FILE *fp, char *buf);
DLLAPI int FCGI_fseek(FCGI_FILE *fp, long offset, int whence);
DLLAPI int FCGI_ftell(FCGI_FILE *fp);
DLLAPI void FCGI_rewind(FCGI_FILE *fp);
#ifdef HAVE_FPOS
DLLAPI int FCGI_fgetpos(FCGI_FILE *fp, fpos_t *pos);
DLLAPI int FCGI_fsetpos(FCGI_FILE *fp, const fpos_t *pos);
#endif
DLLAPI int FCGI_fgetc(FCGI_FILE *fp);
DLLAPI int FCGI_getchar(void);
DLLAPI int FCGI_ungetc(int c, FCGI_FILE *fp);
DLLAPI char *FCGI_fgets(char *str, int size, FCGI_FILE *fp);
DLLAPI char *FCGI_gets(char *str);
/*
* Not yet implemented
*
* int FCGI_fscanf(FCGI_FILE *fp, const char *format, ...);
* int FCGI_scanf(const char *format, ...);
*
*/
DLLAPI int FCGI_fputc(int c, FCGI_FILE *fp);
DLLAPI int FCGI_putchar(int c);
DLLAPI int FCGI_fputs(const char *str, FCGI_FILE *fp);
DLLAPI int FCGI_puts(const char *str);
DLLAPI int FCGI_fprintf(FCGI_FILE *fp, const char *format, ...);
DLLAPI int FCGI_printf(const char *format, ...);
DLLAPI int FCGI_vfprintf(FCGI_FILE *fp, const char *format, va_list ap);
DLLAPI int FCGI_vprintf(const char *format, va_list ap);
DLLAPI size_t FCGI_fread(void *ptr, size_t size, size_t nmemb, FCGI_FILE *fp);
DLLAPI size_t FCGI_fwrite(void *ptr, size_t size, size_t nmemb, FCGI_FILE *fp);
DLLAPI int FCGI_feof(FCGI_FILE *fp);
DLLAPI int FCGI_ferror(FCGI_FILE *fp);
DLLAPI void FCGI_clearerr(FCGI_FILE *fp);
DLLAPI FCGI_FILE *FCGI_tmpfile(void);
DLLAPI int FCGI_fileno(FCGI_FILE *fp);
DLLAPI FCGI_FILE *FCGI_fdopen(int fd, const char *mode);
DLLAPI FCGI_FILE *FCGI_popen(const char *cmd, const char *type);
DLLAPI int FCGI_pclose(FCGI_FILE *);
/*
* The remaining definitions are for application programs,
* not for fcgi_stdio.c
*/
#ifndef NO_FCGI_DEFINES
/*
* Replace standard types, variables, and functions with FastCGI wrappers.
* Use undef in case a macro is already defined.
*/
#undef FILE
#define FILE FCGI_FILE
#undef stdin
#define stdin FCGI_stdin
#undef stdout
#define stdout FCGI_stdout
#undef stderr
#define stderr FCGI_stderr
#undef perror
#define perror FCGI_perror
#undef fopen
#define fopen FCGI_fopen
#undef fclose
#define fclose FCGI_fclose
#undef fflush
#define fflush FCGI_fflush
#undef freopen
#define freopen FCGI_freopen
#undef setvbuf
#define setvbuf FCGI_setvbuf
#undef setbuf
#define setbuf FCGI_setbuf
#undef fseek
#define fseek FCGI_fseek
#undef ftell
#define ftell FCGI_ftell
#undef rewind
#define rewind FCGI_rewind
#undef fgetpos
#define fgetpos FCGI_fgetpos
#undef fsetpos
#define fsetpos FCGI_fsetpos
#undef fgetc
#define fgetc FCGI_fgetc
#undef getc
#define getc FCGI_fgetc
#undef getchar
#define getchar FCGI_getchar
#undef ungetc
#define ungetc FCGI_ungetc
#undef fgets
#define fgets FCGI_fgets
#undef gets
#define gets FCGI_gets
#undef fputc
#define fputc FCGI_fputc
#undef putc
#define putc FCGI_fputc
#undef putchar
#define putchar FCGI_putchar
#undef fputs
#define fputs FCGI_fputs
#undef puts
#define puts FCGI_puts
#undef fprintf
#define fprintf FCGI_fprintf
#undef printf
#define printf FCGI_printf
#undef vfprintf
#define vfprintf FCGI_vfprintf
#undef vprintf
#define vprintf FCGI_vprintf
#undef fread
#define fread FCGI_fread
#undef fwrite
#define fwrite FCGI_fwrite
#undef feof
#define feof FCGI_feof
#undef ferror
#define ferror FCGI_ferror
#undef clearerr
#define clearerr FCGI_clearerr
#undef tmpfile
#define tmpfile FCGI_tmpfile
#undef fileno
#define fileno FCGI_fileno
#undef fdopen
#define fdopen FCGI_fdopen
#undef popen
#define popen FCGI_popen
#undef pclose
#define pclose FCGI_pclose
#endif /* NO_FCGI_DEFINES */
#if defined (__cplusplus) || defined (c_plusplus)
} /* terminate extern "C" { */
#endif
#endif /* _FCGI_STDIO */