Linux 中最重要的软件开发工具是 gcc。gcc是 GNU 的 C 和 C++ 编译器。实际上,gcc能够编译三种语言:C、C++ 和 Object C(C 语言的一种面向对象扩展)。利用 gcc 命令可同时编译并连接 C 和 C++ 源程序。

在学习之前需要了解的是,在使用gcc或g++执行编译的时候,具体的过程如何。如下所示:

1、预处理,生成.i的文件 [预处理器cpp]
2、将预处理后的文件不转换成汇编语言,生成文件.s [编译器egcs]
3、有汇编变为目标代码(机器代码)生成.o的文件 [汇编器as]
4、连接目标代码,生成可执行程序 [链接器ld]

通过对常用的选项,举例学习实践如下。






主要学习如下gcc选项:


-o、-x、-c、-S、-E、-pipe




主要就是使用一个最简单的C程序HelloWorld.c,如下所示:






#include <stdio.h>

int main()
{
    printf("Hello,the world!\n");
    return 0;
}



后面不再说明,除非特殊说明,否则就是指这一段简单的程序。

1、默认编译


比如,你写了一个最简单的C程序HelloWorld.c,如下所示:






#include <stdio.h>

int main()
{
    printf("Hello,the world!\n");
    return 0;
}



编译运行:

[root@shirdrn junys]# gcc HelloWorld.c
[root@shirdrn junys]# ./a.out
Hello,the world!

这时,会默认生成一个a.out文件。运行就能看到程序运行输出“Hello,the world!”。

2、-o 选项

指定目标名称,缺省的时候,gcc 编译出来的文件是a.out,如果你想指定一个其他的名称时,可以使用-o选项。

编译运行:

[root@shirdrn junys]# gcc -o HelloWorld HelloWorld.c
[root@shirdrn junys]# ./HelloWorld
Hello,the world!

就能看到程序运行输出“Hello,the world!”。

3、 -x 选项

具体格式为: -x language filename

其中,language表示语言,例如C语言的后缀名称是.c的,而C++的后缀名是.C或者.cpp;filename表示一个待执行的程序文件,可以使用任何扩展名。

实际上,该-x选项会自动忽略filename程序文件的扩展名,而将filename看成是一个language语言的程序文件并进行编译。

比如,你写了一个最简单的C程序,但是完整文件名称为HelloWorld.shirdrn,扩展名为.shridrn,代码如下所示:






#include <stdio.h>

int main()
{
    printf("Hello,the world!\n");
    return 0;
}



编译运行:

[root@shirdrn junys]# gcc -o HelloWorld.srn -x c HelloWorld.shirdrn
[root@shirdrn junys]# ./HelloWorld.srn
Hello,the world!

4、-c 选项

编译、汇编到目标代码,不进行链接,也就是只生成目标文件(扩展名为.o的目标文件)。

使用-c选项进行编译:

[root@shirdrn junys]# gcc -c HelloWorld.c

这时,可以看到,只是生成了一个HelloWorld.o的目标文件,当然它是一个二进制文件了。

5、 -S 选项

编译到汇编语言,不进行汇编和链接,就是指把文件编译成为汇编代码。

使用-S选项进行编译:

[root@shirdrn junys]# gcc -S HelloWorld.c

可以看到,生成了一个HelloWorld.s文件,使用“文本编辑器”查看该文件,可以看到生成的汇编代码,如下所示:






    .file    "HelloWorld.c"
    .section    .rodata
.LC0:
    .string    "Hello,the world!"
    .text
.globl main
    .type    main, @function
main:
    leal    4(%esp), %ecx
    andl    $-16, %esp
    pushl    -4(%ecx)
    pushl    %ebp
    movl    %esp, %ebp
    pushl    %ecx
    subl    $4, %esp
    movl    $.LC0, (%esp)
    call    puts
    movl    $0, %eax
    addl    $4, %esp
    popl    %ecx
    popl    %ebp
    leal    -4(%ecx), %esp
    ret
    .size    main, .-main
    .ident    "GCC: (GNU) 4.1.2 20070502 (Red Hat 4.1.2-12)"
    .section    .note.GNU-stack,"",@progbits



还没有将汇编代码汇编成目标文件。

6、 -E 选项


仅作预处理,不进行编译、汇编和链接,它不生成任何文件,你需要把它重定向到一个输出文件里面进行查看。

使用 -E 选项进行编译:

[root@shirdrn junys]# gcc -E HelloWorld.c
或者
[root@shirdrn junys]# gcc -E HelloWorld.c > HelloWorld.txt

你可以查看HelloWorld.txt文件,预处理要执行很多的东西,共有933行,片段如下所示:







# 1 "HelloWorld.c"
# 1 "<built-in>"
# 1 "<command line>"
# 1 "HelloWorld.c"
# 1 "/usr/include/stdio.h" 1 3 4
# 28 "/usr/include/stdio.h" 3 4
# 1 "/usr/include/features.h" 1 3 4
# 328 "/usr/include/features.h" 3 4
# 1 "/usr/include/sys/cdefs.h" 1 3 4
# 324 "/usr/include/sys/cdefs.h" 3 4
# 1 "/usr/include/bits/wordsize.h" 1 3 4
# 325 "/usr/include/sys/cdefs.h" 2 3 4
# 329 "/usr/include/features.h" 2 3 4
# 351 "/usr/include/features.h" 3 4
# 1 "/usr/include/gnu/stubs.h" 1 3 4

# 1 "/usr/include/bits/wordsize.h" 1 3 4
# 5 "/usr/include/gnu/stubs.h" 2 3 4

# 1 "/usr/include/gnu/stubs-32.h" 1 3 4
# 8 "/usr/include/gnu/stubs.h" 2 3 4
# 352 "/usr/include/features.h" 2 3 4
# 29 "/usr/include/stdio.h" 2 3 4

# 1 "/usr/lib/gcc/i386-redhat-linux/4.1.2/include/stddef.h" 1 3 4
# 214 "/usr/lib/gcc/i386-redhat-linux/4.1.2/include/stddef.h" 3 4
typedef unsigned int size_t;
# 35 "/usr/include/stdio.h" 2 3 4

# 1 "/usr/include/bits/types.h" 1 3 4
# 28 "/usr/include/bits/types.h" 3 4
# 1 "/usr/include/bits/wordsize.h" 1 3 4
# 29 "/usr/include/bits/types.h" 2 3 4

# 1 "/usr/lib/gcc/i386-redhat-linux/4.1.2/include/stddef.h" 1 3 4
# 32 "/usr/include/bits/types.h" 2 3 4

typedef unsigned char __u_char;
typedef unsigned short int __u_short;
typedef unsigned int __u_int;
typedef unsigned long int __u_long;

typedef signed char __int8_t;
typedef unsigned char __uint8_t;
typedef signed short int __int16_t;
typedef unsigned short int __uint16_t;
typedef signed int __int32_t;
typedef unsigned int __uint32_t;

__extension__ typedef signed long long int __int64_t;
__extension__ typedef unsigned long long int __uint64_t;

__extension__ typedef long long int __quad_t;
__extension__ typedef unsigned long long int __u_quad_t;
# 134 "/usr/include/bits/types.h" 3 4
# 1 "/usr/include/bits/typesizes.h" 1 3 4
# 135 "/usr/include/bits/types.h" 2 3 4

__extension__ typedef __u_quad_t __dev_t;
__extension__ typedef unsigned int __uid_t;
__extension__ typedef unsigned int __gid_t;
__extension__ typedef unsigned long int __ino_t;
__extension__ typedef __u_quad_t __ino64_t;
__extension__ typedef unsigned int __mode_t;
__extension__ typedef unsigned int __nlink_t;
__extension__ typedef long int __off_t;
__extension__ typedef __quad_t __off64_t;
__extension__ typedef int __pid_t;
__extension__ typedef struct { int __val[2]; } __fsid_t;
__extension__ typedef long int __clock_t;
__extension__ typedef unsigned long int __rlim_t;
__extension__ typedef __u_quad_t __rlim64_t;
__extension__ typedef unsigned int __id_t;
__extension__ typedef long int __time_t;
__extension__ typedef unsigned int __useconds_t;
__extension__ typedef long int __suseconds_t;

__extension__ typedef int __daddr_t;
__extension__ typedef long int __swblk_t;
__extension__ typedef int __key_t;

__extension__ typedef int __clockid_t;

__extension__ typedef void * __timer_t;

__extension__ typedef long int __blksize_t;

__extension__ typedef long int __blkcnt_t;
__extension__ typedef __quad_t __blkcnt64_t;

__extension__ typedef unsigned long int __fsblkcnt_t;
__extension__ typedef __u_quad_t __fsblkcnt64_t;

__extension__ typedef unsigned long int __fsfilcnt_t;
__extension__ typedef __u_quad_t __fsfilcnt64_t;

__extension__ typedef int __ssize_t;


typedef __off64_t __loff_t;
typedef __quad_t *__qaddr_t;
typedef char *__caddr_t;

__extension__ typedef int __intptr_t;

__extension__ typedef unsigned int __socklen_t;
# 37 "/usr/include/stdio.h" 2 3 4
# 45 "/usr/include/stdio.h" 3 4
struct _IO_FILE;

typedef struct _IO_FILE FILE;

# 65 "/usr/include/stdio.h" 3 4
typedef struct _IO_FILE __FILE;
# 75 "/usr/include/stdio.h" 3 4
# 1 "/usr/include/libio.h" 1 3 4
# 32 "/usr/include/libio.h" 3 4
# 1 "/usr/include/_G_config.h" 1 3 4
# 14 "/usr/include/_G_config.h" 3 4
# 1 "/usr/lib/gcc/i386-redhat-linux/4.1.2/include/stddef.h" 1 3 4
# 326 "/usr/lib/gcc/i386-redhat-linux/4.1.2/include/stddef.h" 3 4
typedef long int wchar_t;
# 355 "/usr/lib/gcc/i386-redhat-linux/4.1.2/include/stddef.h" 3 4
typedef unsigned int wint_t;
# 15 "/usr/include/_G_config.h" 2 3 4
# 24 "/usr/include/_G_config.h" 3 4
# 1 "/usr/include/wchar.h" 1 3 4
# 48 "/usr/include/wchar.h" 3 4
# 1 "/usr/lib/gcc/i386-redhat-linux/4.1.2/include/stddef.h" 1 3 4
# 49 "/usr/include/wchar.h" 2 3 4

# 1 "/usr/include/bits/wchar.h" 1 3 4
# 51 "/usr/include/wchar.h" 2 3 4
# 76 "/usr/include/wchar.h" 3 4
typedef struct
{
int __count;
union
{
    wint_t __wch;
    char __wchb[4];
} __value;
} __mbstate_t;
# 25 "/usr/include/_G_config.h" 2 3 4

typedef struct
{
__off_t __pos;
__mbstate_t __state;
} _G_fpos_t;
typedef struct
{
__off64_t __pos;
__mbstate_t __state;
} _G_fpos64_t;
# 44 "/usr/include/_G_config.h" 3 4
# 1 "/usr/include/gconv.h" 1 3 4
# 28 "/usr/include/gconv.h" 3 4
# 1 "/usr/include/wchar.h" 1 3 4
# 48 "/usr/include/wchar.h" 3 4
# 1 "/usr/lib/gcc/i386-redhat-linux/4.1.2/include/stddef.h" 1 3 4
# 49 "/usr/include/wchar.h" 2 3 4
# 29 "/usr/include/gconv.h" 2 3 4


# 1 "/usr/lib/gcc/i386-redhat-linux/4.1.2/include/stddef.h" 1 3 4
# 32 "/usr/include/gconv.h" 2 3 4

enum
{
__GCONV_OK = 0,
__GCONV_NOCONV,
__GCONV_NODB,
__GCONV_NOMEM,

__GCONV_EMPTY_INPUT,
__GCONV_FULL_OUTPUT,
__GCONV_ILLEGAL_INPUT,
__GCONV_INCOMPLETE_INPUT,

__GCONV_ILLEGAL_DESCRIPTOR,
__GCONV_INTERNAL_ERROR
};

enum
{
__GCONV_IS_LAST = 0x0001,
__GCONV_IGNORE_ERRORS = 0x0002
};

struct __gconv_step;
struct __gconv_step_data;
struct __gconv_loaded_object;
struct __gconv_trans_data;

typedef int (*__gconv_fct) (struct __gconv_step *, struct __gconv_step_data *,
       __const unsigned char **, __const unsigned char *,
       unsigned char **, size_t *, int, int);

typedef wint_t (*__gconv_btowc_fct) (struct __gconv_step *, unsigned char);

typedef int (*__gconv_init_fct) (struct __gconv_step *);
typedef void (*__gconv_end_fct) (struct __gconv_step *);

typedef int (*__gconv_trans_fct) (struct __gconv_step *,
      struct __gconv_step_data *, void *,
      __const unsigned char *,
      __const unsigned char **,
      __const unsigned char *, unsigned char **,
      size_t *);

typedef int (*__gconv_trans_context_fct) (void *, __const unsigned char *,
       __const unsigned char *,
       unsigned char *, unsigned char *);

typedef int (*__gconv_trans_query_fct) (__const char *, __const char ***,
     size_t *);


typedef int (*__gconv_trans_init_fct) (void **, const char *);
typedef void (*__gconv_trans_end_fct) (void *);

struct __gconv_trans_data
{

__gconv_trans_fct __trans_fct;
__gconv_trans_context_fct __trans_context_fct;
__gconv_trans_end_fct __trans_end_fct;
void *__data;
struct __gconv_trans_data *__next;
};

struct __gconv_step
{
struct __gconv_loaded_object *__shlib_handle;
__const char *__modname;

int __counter;

char *__from_name;
char *__to_name;

__gconv_fct __fct;
__gconv_btowc_fct __btowc_fct;
__gconv_init_fct __init_fct;
__gconv_end_fct __end_fct;

int __min_needed_from;
int __max_needed_from;
int __min_needed_to;
int __max_needed_to;

int __stateful;

void *__data;
};

struct __gconv_step_data
{
unsigned char *__outbuf;
unsigned char *__outbufend;

int __flags;

int __invocation_counter;

int __internal_use;

__mbstate_t *__statep;
__mbstate_t __state;

struct __gconv_trans_data *__trans;
};

typedef struct __gconv_info
{
size_t __nsteps;
struct __gconv_step *__steps;
__extension__ struct __gconv_step_data __data [];
} *__gconv_t;
# 45 "/usr/include/_G_config.h" 2 3 4
typedef union
{
struct __gconv_info __cd;
struct
{
    struct __gconv_info __cd;
    struct __gconv_step_data __data;
} __combined;
} _G_iconv_t;

typedef int _G_int16_t __attribute__ ((__mode__ (__HI__)));
typedef int _G_int32_t __attribute__ ((__mode__ (__SI__)));
typedef unsigned int _G_uint16_t __attribute__ ((__mode__ (__HI__)));
typedef unsigned int _G_uint32_t __attribute__ ((__mode__ (__SI__)));
# 33 "/usr/include/libio.h" 2 3 4
# 53 "/usr/include/libio.h" 3 4
# 1 "/usr/lib/gcc/i386-redhat-linux/4.1.2/include/stdarg.h" 1 3 4
# 43 "/usr/lib/gcc/i386-redhat-linux/4.1.2/include/stdarg.h" 3 4
typedef __builtin_va_list __gnuc_va_list;
# 54 "/usr/include/libio.h" 2 3 4
# 167 "/usr/include/libio.h" 3 4
struct _IO_jump_t; struct _IO_FILE;
# 177 "/usr/include/libio.h" 3 4
typedef void _IO_lock_t;

struct _IO_marker {
struct _IO_marker *_next;
struct _IO_FILE *_sbuf;

int _pos;
# 200 "/usr/include/libio.h" 3 4
};

enum __codecvt_result
{
__codecvt_ok,
__codecvt_partial,
__codecvt_error,
__codecvt_noconv
};
# 268 "/usr/include/libio.h" 3 4
struct _IO_FILE {
int _flags;

char* _IO_read_ptr;
char* _IO_read_end;
char* _IO_read_base;
char* _IO_write_base;
char* _IO_write_ptr;
char* _IO_write_end;
char* _IO_buf_base;
char* _IO_buf_end;

char *_IO_save_base;
char *_IO_backup_base;
char *_IO_save_end;

struct _IO_marker *_markers;

struct _IO_FILE *_chain;

int _fileno;

int _flags2;

__off_t _old_offset;

unsigned short _cur_column;
signed char _vtable_offset;
char _shortbuf[1];

_IO_lock_t *_lock;
# 316 "/usr/include/libio.h" 3 4
__off64_t _offset;
# 325 "/usr/include/libio.h" 3 4
void *__pad1;
void *__pad2;
void *__pad3;
void *__pad4;
size_t __pad5;

int _mode;

char _unused2[15 * sizeof (int) - 4 * sizeof (void *) - sizeof (size_t)];

};

typedef struct _IO_FILE _IO_FILE;

struct _IO_FILE_plus;

extern struct _IO_FILE_plus _IO_2_1_stdin_;
extern struct _IO_FILE_plus _IO_2_1_stdout_;
extern struct _IO_FILE_plus _IO_2_1_stderr_;
# 361 "/usr/include/libio.h" 3 4
typedef __ssize_t __io_read_fn (void *__cookie, char *__buf, size_t __nbytes);

typedef __ssize_t __io_write_fn (void *__cookie, __const char *__buf,
     size_t __n);

typedef int __io_seek_fn (void *__cookie, __off64_t *__pos, int __w);

typedef int __io_close_fn (void *__cookie);
# 413 "/usr/include/libio.h" 3 4
extern int __underflow (_IO_FILE *);
extern int __uflow (_IO_FILE *);
extern int __overflow (_IO_FILE *, int);
extern wint_t __wunderflow (_IO_FILE *);
extern wint_t __wuflow (_IO_FILE *);
extern wint_t __woverflow (_IO_FILE *, wint_t);
# 451 "/usr/include/libio.h" 3 4
extern int _IO_getc (_IO_FILE *__fp);
extern int _IO_putc (int __c, _IO_FILE *__fp);
extern int _IO_feof (_IO_FILE *__fp) __attribute__ ((__nothrow__));
extern int _IO_ferror (_IO_FILE *__fp) __attribute__ ((__nothrow__));

extern int _IO_peekc_locked (_IO_FILE *__fp);

extern void _IO_flockfile (_IO_FILE *) __attribute__ ((__nothrow__));
extern void _IO_funlockfile (_IO_FILE *) __attribute__ ((__nothrow__));
extern int _IO_ftrylockfile (_IO_FILE *) __attribute__ ((__nothrow__));
# 481 "/usr/include/libio.h" 3 4
extern int _IO_vfscanf (_IO_FILE * __restrict, const char * __restrict,
   __gnuc_va_list, int *__restrict);
extern int _IO_vfprintf (_IO_FILE *__restrict, const char *__restrict,
    __gnuc_va_list);
extern __ssize_t _IO_padn (_IO_FILE *, int, __ssize_t);
extern size_t _IO_sgetn (_IO_FILE *, void *, size_t);

extern __off64_t _IO_seekoff (_IO_FILE *, __off64_t, int, int);
extern __off64_t _IO_seekpos (_IO_FILE *, __off64_t, int);

extern void _IO_free_backup_area (_IO_FILE *) __attribute__ ((__nothrow__));
# 76 "/usr/include/stdio.h" 2 3 4
# 89 "/usr/include/stdio.h" 3 4

typedef _G_fpos_t fpos_t;

# 141 "/usr/include/stdio.h" 3 4
# 1 "/usr/include/bits/stdio_lim.h" 1 3 4
# 142 "/usr/include/stdio.h" 2 3 4

extern struct _IO_FILE *stdin;
extern struct _IO_FILE *stdout;
extern struct _IO_FILE *stderr;

extern int remove (__const char *__filename) __attribute__ ((__nothrow__));

extern int rename (__const char *__old, __const char *__new) __attribute__ ((__nothrow__));

extern FILE *tmpfile (void) ;
# 188 "/usr/include/stdio.h" 3 4
extern char *tmpnam (char *__s) __attribute__ ((__nothrow__)) ;

extern char *tmpnam_r (char *__s) __attribute__ ((__nothrow__)) ;
# 206 "/usr/include/stdio.h" 3 4
extern char *tempnam (__const char *__dir, __const char *__pfx)
     __attribute__ ((__nothrow__)) __attribute__ ((__malloc__)) ;

extern int fclose (FILE *__stream);

extern int fflush (FILE *__stream);

# 231 "/usr/include/stdio.h" 3 4
extern int fflush_unlocked (FILE *__stream);
# 245 "/usr/include/stdio.h" 3 4

extern FILE *fopen (__const char *__restrict __filename,
      __const char *__restrict __modes) ;

extern FILE *freopen (__const char *__restrict __filename,
        __const char *__restrict __modes,
        FILE *__restrict __stream) ;
# 274 "/usr/include/stdio.h" 3 4

# 285 "/usr/include/stdio.h" 3 4
extern FILE *fdopen (int __fd, __const char *__modes) __attribute__ ((__nothrow__)) ;
# 306 "/usr/include/stdio.h" 3 4

extern void setbuf (FILE *__restrict __stream, char *__restrict __buf) __attribute__ ((__nothrow__));

extern int setvbuf (FILE *__restrict __stream, char *__restrict __buf,
      int __modes, size_t __n) __attribute__ ((__nothrow__));

extern void setbuffer (FILE *__restrict __stream, char *__restrict __buf,
         size_t __size) __attribute__ ((__nothrow__));

extern void setlinebuf (FILE *__stream) __attribute__ ((__nothrow__));

extern int fprintf (FILE *__restrict __stream,
      __const char *__restrict __format, ...);

extern int printf (__const char *__restrict __format, ...);

extern int sprintf (char *__restrict __s,
      __const char *__restrict __format, ...) __attribute__ ((__nothrow__));

extern int vfprintf (FILE *__restrict __s, __const char *__restrict __format,
       __gnuc_va_list __arg);

extern int vprintf (__const char *__restrict __format, __gnuc_va_list __arg);

extern int vsprintf (char *__restrict __s, __const char *__restrict __format,
       __gnuc_va_list __arg) __attribute__ ((__nothrow__));

extern int snprintf (char *__restrict __s, size_t __maxlen,
       __const char *__restrict __format, ...)
     __attribute__ ((__nothrow__)) __attribute__ ((__format__ (__printf__, 3, 4)));

extern int vsnprintf (char *__restrict __s, size_t __maxlen,
        __const char *__restrict __format, __gnuc_va_list __arg)
     __attribute__ ((__nothrow__)) __attribute__ ((__format__ (__printf__, 3, 0)));

# 400 "/usr/include/stdio.h" 3 4

extern int fscanf (FILE *__restrict __stream,
     __const char *__restrict __format, ...) ;

extern int scanf (__const char *__restrict __format, ...) ;

extern int sscanf (__const char *__restrict __s,
     __const char *__restrict __format, ...) __attribute__ ((__nothrow__));

# 442 "/usr/include/stdio.h" 3 4

extern int fgetc (FILE *__stream);
extern int getc (FILE *__stream);

extern int getchar (void);

# 466 "/usr/include/stdio.h" 3 4
extern int getc_unlocked (FILE *__stream);
extern int getchar_unlocked (void);
# 477 "/usr/include/stdio.h" 3 4
extern int fgetc_unlocked (FILE *__stream);

extern int fputc (int __c, FILE *__stream);
extern int putc (int __c, FILE *__stream);

extern int putchar (int __c);

# 510 "/usr/include/stdio.h" 3 4
extern int fputc_unlocked (int __c, FILE *__stream);

extern int putc_unlocked (int __c, FILE *__stream);
extern int putchar_unlocked (int __c);

extern int getw (FILE *__stream);

extern int putw (int __w, FILE *__stream);

extern char *fgets (char *__restrict __s, int __n, FILE *__restrict __stream)
     ;

extern char *gets (char *__s) ;

# 591 "/usr/include/stdio.h" 3 4

extern int fputs (__const char *__restrict __s, FILE *__restrict __stream);

extern int puts (__const char *__s);

extern int ungetc (int __c, FILE *__stream);

extern size_t fread (void *__restrict __ptr, size_t __size,
       size_t __n, FILE *__restrict __stream) ;

extern size_t fwrite (__const void *__restrict __ptr, size_t __size,
        size_t __n, FILE *__restrict __s) ;

# 644 "/usr/include/stdio.h" 3 4
extern size_t fread_unlocked (void *__restrict __ptr, size_t __size,
         size_t __n, FILE *__restrict __stream) ;
extern size_t fwrite_unlocked (__const void *__restrict __ptr, size_t __size,
          size_t __n, FILE *__restrict __stream) ;

extern int fseek (FILE *__stream, long int __off, int __whence);

extern long int ftell (FILE *__stream) ;

extern void rewind (FILE *__stream);

# 680 "/usr/include/stdio.h" 3 4
extern int fseeko (FILE *__stream, __off_t __off, int __whence);

extern __off_t ftello (FILE *__stream) ;
# 699 "/usr/include/stdio.h" 3 4

extern int fgetpos (FILE *__restrict __stream, fpos_t *__restrict __pos);

extern int fsetpos (FILE *__stream, __const fpos_t *__pos);
# 722 "/usr/include/stdio.h" 3 4

# 731 "/usr/include/stdio.h" 3 4

extern void clearerr (FILE *__stream) __attribute__ ((__nothrow__));

extern int feof (FILE *__stream) __attribute__ ((__nothrow__)) ;

extern int ferror (FILE *__stream) __attribute__ ((__nothrow__)) ;

extern void clearerr_unlocked (FILE *__stream) __attribute__ ((__nothrow__));
extern int feof_unlocked (FILE *__stream) __attribute__ ((__nothrow__)) ;
extern int ferror_unlocked (FILE *__stream) __attribute__ ((__nothrow__)) ;

extern void perror (__const char *__s);

# 1 "/usr/include/bits/sys_errlist.h" 1 3 4
# 27 "/usr/include/bits/sys_errlist.h" 3 4
extern int sys_nerr;
extern __const char *__const sys_errlist[];
# 761 "/usr/include/stdio.h" 2 3 4

extern int fileno (FILE *__stream) __attribute__ ((__nothrow__)) ;

extern int fileno_unlocked (FILE *__stream) __attribute__ ((__nothrow__)) ;
# 780 "/usr/include/stdio.h" 3 4
extern FILE *popen (__const char *__command, __const char *__modes) ;

extern int pclose (FILE *__stream);

extern char *ctermid (char *__s) __attribute__ ((__nothrow__));
# 820 "/usr/include/stdio.h" 3 4
extern void flockfile (FILE *__stream) __attribute__ ((__nothrow__));

extern int ftrylockfile (FILE *__stream) __attribute__ ((__nothrow__)) ;

extern void funlockfile (FILE *__stream) __attribute__ ((__nothrow__));
# 850 "/usr/include/stdio.h" 3 4

# 2 "HelloWorld.c" 2

int main()
{
printf("Hello,the world!\n");
return 0;
}




7、-pipe 选项

使用管道代替编译中临时文件。

使用-pipe选项编译运行:

[root@shirdrn junys]# gcc -pipe -o HelloWorld HelloWorld.c
[root@shirdrn junys]# ./HelloWorld
Hello,the world!

该选项,使用管道代替临时文件,表面上,并没有看出有什么特别的。


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