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What is char far datatype in c language?
The far memory type may be used for variables and constants. This memory is accessed using 24-bit addresses and may be on-chip or external.For variables, far memory is limited to 16M. Objects are limited to 64K and may not cross a 64K boundary. Variables declared far are located in the HDATA memory class.For constants (ROM variables), far memory is limited to 16M. Objects are limited to 64K and may not cross a 64K boundary. Constant variables declared far are located in the HCONST group.Declare far objects as follows: unsigned char farfar_variable; unsigned char const farfar_const_variable;
What is structure alignment in C?
Structure alignment relates to the way objects in memory must be allocated according to the underlying architecture. For instance, a machine might expect an int to be aligned upon a 4-byte boundary. If that is the case then a structure with a member int must be aligned upon a 4-byte boundary and the int member offset from that boundary by some multiple of 4 bytes. Consider the following: struct X_ { char c; int i; } X; assert (sizeof(X)==sizeof(int)+sizeof(char)); /* oops */ Assuming sizeof(int) is 4 and sizeof(char) is 1 and that an int must be aligned on a 4-byte boundary, the actual length of this structure must be 8 bytes, not the 5 we expected. If it were anything other than 8, then an array of such structures would have misalignments in 3 out of every 4 elements. Note that in order to correctly align this structure, the compiler must insert 3 padding bytes immediately after the char member. This ensures that the int member is offset 4 bytes from the start of the structure. So long as the structure itself is aligned upon a 4-byte boundary (which it now will be because 8 is a multiple of 4), the int will always be correctly aligned. Inserting padding bytes between members can often increase a structure's size far more than we might expect, particularly if there are many members. To avoid this, it is best to declare members in order of size, largest first. In this way, whenever padding is required, the padding is more likely to be placed at the end of the structure rather than between two or more members. struct X_ { char c; int i; char c2; } X; Given the same criteria as before, this structure would be 12 bytes in length. But by changing the order of the members, we can reduce this to just 8 bytes: struct X_ { int i; char c; char c2; } X; The reason this works is because a char can always be aligned on a 1-byte boundary, so two consecutive char members will easily fit inside a 4-byte word. Thus we only require 2 bytes of padding instead of 4. Note that it is never safe to assume the lengths of any data type in C other than char which is always sizeof(char)==1. The lengths of all other types are measured in terms of a char, but will vary from system to system according to the underlying architecture. Always use the sizeof() operator to determine type lengths. Note that the sizeof() operator computes data type lengths at compile time, so there is no runtime cost, nor is there any need to store the return value.
Importance of data structure?
Data structure is important since it dictates the types of operations we can perform on the data and how efficiently they can be carried out. It also dictates how dynamic we can be in dealing with our data; for example it dictates if we can add additional data on the fly or if we need to know about all of the data up front. We determine which data structures to use to store our data only after we've carefully analyzed the problem and know at least what it is we hope to do with the data; for example if we'll require random access, or sequential access, or the ability to move both forward and backward through the data.
What is the function of dos.h?
You can find a copy of that file in here: http://ftp.ibiblio.org/pub/micro/PC-stuff/freedos/files/devel/c/dos.h in case the server is down check the extracted file: #ifndef __DOS_H #define __DOS_H #include <_defs.h> #include <stddef.h> #ifdef __WATCOMC__ #pragma pack( __push, 1 ) #endif struct _R16BIT { unsigned short ax, bx, cx, dx, si, di, es, cs, ss, ds, flags; unsigned char cflag; }; struct _R8BIT { unsigned char al, ah, bl, bh, cl, ch, dl, dh; }; union _INTR { struct _R16BIT x; struct _R8BIT h; }; #define INTR _INTR struct country { int co_date; /* date format */ char co_curr[ 5 ]; /* currency symbol */ char co_thsep[ 2 ]; /* thousands separator */ char co_desep[ 2 ]; /* decimal separator */ char co_dtsep[ 2 ]; /* date separator */ char co_tmsep[ 2 ]; /* time separator */ char co_currstyle; /* currency style */ char co_digits; /* significant digits in currency */ char co_time; /* time format */ long co_case; /* case map */ char co_dasep[ 2 ]; /* data separator */ char co_fill[ 10 ]; /* filler */ }; #define COUNTRY country struct DOSERROR { int de_exterror; /* extended error */ char de_class; /* error class */ char de_action; /* action */ char de_locus; /* error locus */ }; struct date { unsigned int da_year; /* current year */ unsigned char da_day; /* day of the month */ unsigned char da_mon; /* month (1 = Jan) */ }; struct dosdate_t { unsigned char day; /* 1--31 */ unsigned char month; /* 1--12 */ unsigned int year; /* 1980--2099 */ unsigned char dayofweek; /* 0--6; 0 = Sunday */ }; struct devhdr { long dh_next; short dh_attr; unsigned short dh_strat; unsigned short dh_inter; char dh_name[ 8 ]; }; struct dfree { unsigned df_avail; /* Available clusters */ unsigned df_total; /* Total clusters */ unsigned df_bsec; /* Bytes per sector */ unsigned df_sclus; /* Sectors per cluster */ }; struct diskfree_t { unsigned total_clusters; unsigned avail_clusters; unsigned sectors_per_cluster; unsigned bytes_per_sector; }; typedef struct { char drive; char pattern [ 13 ]; char reserved [ 7 ]; char attrib; short time; short date; long size; char nameZ [ 13 ]; } dosSearchInfo; struct fatinfo { char fi_sclus; /* sectors per cluster */ char fi_fatid; /* the FAT id byte */ int fi_nclus; /* number of clusters */ int fi_bysec; /* bytes per sector */ }; struct ffblk { #ifdef __CLIB_LFN__ unsigned short cr_time; /* time of file creation */ unsigned short cr_date; /* date of file creation */ unsigned short ac_time; /* time of last file access */ unsigned short ac_date; /* date of last file access */ char ff_reserved[ 13 ]; /* reserved for use by DOS */ #else char ff_reserved[ 21 ]; /* reserved for use by DOS */ #endif char ff_attrib; /* attribute byte for file */ unsigned short ff_ftime; /* time of last write to file */ unsigned short ff_fdate; /* date of last write to file */ unsigned long ff_fsize; /* length of file in bytes */ #ifdef __CLIB_LFN__ char ff_name[ 256 ]; /* null-terminated filename */ unsigned short lfnhandle;/* DOS LFN support handle */ #else char ff_name[ 13 ]; /* null-terminated filename */ #endif }; struct find_t { #ifdef __CLIB_LFN__ unsigned short cr_time; /* time of file creation */ unsigned short cr_date; /* date of file creation */ unsigned short ac_time; /* time of last file access */ unsigned short ac_date; /* date of last file access */ char reserved[ 13 ]; /* reserved for use by DOS */ #else char reserved[ 21 ]; /* reserved for use by DOS */ #endif char attrib; /* attribute byte for file */ unsigned short wr_time; /* time of last write to file */ unsigned short wr_date; /* date of last write to file */ unsigned long size; /* length of file in bytes */ #ifdef __CLIB_LFN__ char name[ 256 ]; /* null-terminated filename */ unsigned short lfnhandle;/* DOS LFN support handle */ #else char name[ 13 ]; /* null-terminated filename */ #endif }; #define _find_t find_t struct fcb { char fcb_drive; char fcb_name[ 8 ], fcb_ext[ 3 ]; short fcb_curblk, fcb_recsize; long fcb_filsize; short fcb_date; char fcb_resv[ 10 ], fcb_currec; long fcb_random; }; struct xfcb { char xfcb_flag; char xfcb_resv[ 5 ]; char xfcb_attr; struct fcb xfcb_fcb; }; struct dostime_t { unsigned char hour; /* Hours */ unsigned char minute; /* Minutes */ unsigned char second; /* Seconds */ unsigned char hsecond; /* Hundredths of seconds */ }; struct time { unsigned char ti_min; /* minutes */ unsigned char ti_hour; /* hours */ unsigned char ti_hund; /* hundredths of seconds */ unsigned char ti_sec; /* seconds */ }; #ifdef __WATCOMC__ #pragma pack( __pop ) #endif extern int __getversion( void ); extern char ** environ; #define _version (*__getversion)() extern unsigned char _osmajor; extern unsigned char _osminor; extern int absread( int drive, int sects, long lsect, void *buffer ); extern int abswrite( int drive, int sects, long lsect, void *buffer ); extern int allocmem( unsigned size, unsigned *seg ); extern int bdos( int ah, unsigned dx, unsigned al ); extern int bdosptr( int ah, void *argument, unsigned al ); extern int _callint( union INTR *regs ); extern struct COUNTRY * country( int xcode, struct COUNTRY *ct ); extern void ctrlbrk( int ( *handler )( void ) ); extern void delay( unsigned mill ); extern void _disable( void ); extern unsigned _dos_allocmem( unsigned size, unsigned *seg ); extern unsigned _dos_close( int handle ); extern unsigned _dos_creat( const char *path, int attr, unsigned *handle ); extern unsigned _dos_creatnew( const char *path, int attr, unsigned *handle ); extern int __cdecl dosexterror( struct DOSERROR *errblk ); extern unsigned _dos_findfirst( char *filename, int attrib, void *strptr ); extern unsigned _dos_findnext( void *strptr ); extern unsigned _dos_findclose( void *strptr ); extern unsigned _dos_freemem( unsigned seg ); extern void __cdecl _dos_getdate( struct dosdate_t *ptr ); extern unsigned __cdecl _dos_getdiskfree( unsigned char dr, struct diskfree_t *d ); extern unsigned _dos_getdrive( unsigned *disk ); extern unsigned _dos_getfileattr( const char *filename, unsigned *attrs ); extern unsigned __cdecl _dos_getftime( int handle, unsigned *date, unsigned *time ); extern void __cdecl _dos_gettime( struct dostime_t *timeptr ); extern void ( interrupt far * _dos_getvect( unsigned intno ) )( ); extern void _dos_keep( unsigned char retcode, unsigned size ); extern unsigned _dos_open( const char *path, unsigned flags, unsigned *handle ); extern unsigned _dos_read( int handle, void far *buf, unsigned len, unsigned *nread ); extern unsigned _dos_setblock( unsigned newsize, unsigned seg, unsigned *max ); extern void _dos_setdate( struct dosdate_t *ptr ); extern void _dos_setdrive( unsigned disk, unsigned *total ); extern unsigned _dos_setfileattr( const char *filename, unsigned attrs ); extern unsigned _dos_setftime( int handle, unsigned date, unsigned time ); extern unsigned _dos_settime( struct dostime_t *timeptr ); extern void _dos_setvect( unsigned intno, void ( interrupt far *vect )() ); extern time_t dostounix( struct date *date, struct time *time ); extern unsigned _dos_write( int handle, void far *buf, unsigned len, unsigned *bytes ); extern void _enable( void ); extern int freemem( unsigned seg ); extern int getcbrk( void ); extern void __cdecl getdate( struct date *datep ); extern void __cdecl getdfree( unsigned char drive, struct dfree *dtable ); extern char * getdta( void ); extern void getfat( unsigned char drive, struct fatinfo *dtable ); extern void getfatd( struct fatinfo *dtable ); extern unsigned getpsp( void ); extern void __cdecl gettime( struct time *timeptr ); extern void ( interrupt far * getvect( int intno ) )( ); extern int getverify( void ); extern int inp( unsigned id ); extern unsigned inpw( unsigned id ); extern unsigned inport( unsigned id ); extern unsigned char inportb( unsigned id ); extern void keep( unsigned char retcode, unsigned size ); extern void nosound( void ); extern int outp( unsigned id, int value ); extern unsigned outpw( unsigned id, unsigned value ); extern void outport( unsigned id, unsigned value ); extern void outportb( unsigned id, unsigned char value ); extern char * parsfnm( const char *cmdline, struct fcb *ptr, int al ); extern int peek( unsigned seg, unsigned offs ); extern char peekb( unsigned seg, unsigned offs ); extern void poke( unsigned seg, unsigned offs, int value ); extern void pokeb( unsigned seg, unsigned offs, char value ); extern int randbrd( struct fcb *buf, int rnum ); extern int randbwr( struct fcb *buf, int rnum ); extern int setblock( unsigned newsize, unsigned seg ); extern int setcbrk( int value ); extern void setdate( struct date *datep ); extern void setdta( char far *dta ); extern void setpsp( unsigned psp ); extern void settime( struct time *timeptr ); extern void setvect( int intno, void ( interrupt far *vect )() ); extern void setverify( int flag ); extern void sleep( unsigned x ); extern void sound( unsigned frequency ); extern void unixtodos( time_t longtime, struct date *date, struct time *time ); extern int unlink( const char *filename ); #define disable _disable #define enable _enable #define _A_NORMAL 0x00 #define _A_RDONLY 0x01 #define _A_HIDDEN 0x02 #define _A_SYSTEM 0x04 #define _A_VOLID 0x08 #define _A_SUBDIR 0x10 #define _A_ARCH 0x20 #define FA_NORMAL _A_NORMAL #define FA_RDONLY _A_RDONLY #define FA_HIDDEN _A_HIDDEN #define FA_SYSTEM _A_SYSTEM #define FA_LABEL _A_VOLID #define FA_DIREC _A_SUBDIR #define FA_ARCH _A_ARCH #define NFDS 20 #define SEEK_SET 0 #define SEEK_CUR 1 #define SEEK_END 2 #define MK_FP( seg, ofs ) ( ( void * )\ ( ( ( unsigned long )( seg ) << 16 ) |\ ( unsigned )( ofs ) ) ) #define FP_SEG(fp) ( ( unsigned )( ( unsigned long )( fp ) >> 16 ) ) #define FP_OFF(fp) ( ( unsigned )( fp ) ) #define __peek( a,b ) ( *( ( int far * ) MK_FP ( ( a ), ( b ) ) ) ) #define __peekb( a,b ) ( *( ( char far * ) MK_FP ( ( a ), ( b ) ) ) ) #define __poke( a,b,c ) ( *( ( int far * ) MK_FP ( (a),(b)) ) = ( int )(c)) #define __pokeb( a,b,c ) ( *( ( char far * ) MK_FP ( (a),(b)) ) = ( char )(c)) #define peek( a,b ) ( *( ( int far * ) MK_FP ( ( a ), ( b ) ) ) ) #define peekb( a,b ) ( *( ( char far * ) MK_FP ( ( a ), ( b ) ) ) ) #define poke( a,b,c ) ( *( ( int far * ) MK_FP ( (a),(b)) ) = ( int )(c)) #define pokeb( a,b,c ) ( *( ( char far * ) MK_FP ( (a),(b)) ) = ( char )(c)) #ifndef __NO_INLINE_FUNCTIONS #pragma aux _enable = "sti"; #pragma aux _disable = "cli"; #pragma aux inp = "in al, dx" parm [dx] value [al] modify [ax dx]; #pragma aux inpw = "in ax, dx" parm [dx] value [ax] modify [ax dx]; #pragma aux inport = "in ax, dx" parm [dx] value [ax] modify [ax dx]; #pragma aux inportb = "in al, dx" parm [dx] value [al] modify [ax dx]; #pragma aux outp = "out dx, al" parm [dx] [al] value [al] modify [ax dx]; #pragma aux outpw = "out dx, ax" parm [dx] [ax] value [ax] modify [ax dx]; #pragma aux outport = "out dx, ax" parm [dx] [ax] modify [ax dx]; #pragma aux outportb = "out dx, al" parm [dx] [al] modify [ax dx]; #endif #endif
What are the commonly used data types in programming languages?
Data types tell the compiler how many bytes will be allocated to the type and how those bytes will be interpreted. For instance, consider the following 64-bit value: 0100101001100001011011100111010101100001011100100111100100000000 In hexadecimal notation this would be written: 0x4a616e7561727900 But what does this value actually mean? Without knowing the type it's impossible to say. It could be any of the following: - a big-endian integer: 5,359,686,481,972,721,920 - a little-endian integer: 34,184,235,089,551,690 - a big-endian float: 2.03809e+050 - a little-endian float: 2.26484e-306 - a null-terminated string: "January" All of these are perfectly valid interpretations for the exact same binary sequence. So in order for the compiler to correctly interpret this binary sequence it has to know what data type is actually being represented by that sequence. If we tell it that the sequence is a string of 8 characters then the compiler will correctly interpret the value as the null-terminated string "January".
What is the difference between '1' and 1 as far as computer memory is concerned with respect to c plus plus?
'1' is a char data type and always consume 1 byte in C++. L'1' is the wide-char equivalent (2 bytes). 1 is implicitly an integer, but its length is dependant upon the C++ implementation and the type being assigned to. If the type is a long, then its length is typically 4 bytes, while a short is typically 2 bytes. The sizeof() operator is the only way to guarantee the length of a given type other than char (which is always 1, regardless of implementation).
Can char pointer contain long address in c?
What do you mean by 'long address'?1. If you are asking about 'near' and 'far' pointers, then you should forget them; simply use Huge Memory Model.2. If you mean the address of a 'long int'-type variable, then yes, with type-cast:long l;char *p = (char *)&l;Note: for generic pointers you can use type void *
What rhymes with parr?
bar char far scar star
What is char far datatype in c language?
The far memory type may be used for variables and constants. This memory is accessed using 24-bit addresses and may be on-chip or external.For variables, far memory is limited to 16M. Objects are limited to 64K and may not cross a 64K boundary. Variables declared far are located in the HDATA memory class.For constants (ROM variables), far memory is limited to 16M. Objects are limited to 64K and may not cross a 64K boundary. Constant variables declared far are located in the HCONST group.Declare far objects as follows: unsigned char farfar_variable; unsigned char const farfar_const_variable;
Eris's gravitational field strength?
Eris is far, far away; it is yet too early to have detailed data on that.Eris is far, far away; it is yet too early to have detailed data on that.Eris is far, far away; it is yet too early to have detailed data on that.Eris is far, far away; it is yet too early to have detailed data on that.
What rhymes with char?
car, far, mar, tar, yar!(pirate), par, har (laugh), jar, bar,
A number far away from most of the numbers in a set of data?
what are numbers that are far from a data set
How massive is an explosion?
Depends entirely on type of charge & qty. Can be infinite as far as size provided enough qty available.
What is structure alignment in C?
Structure alignment relates to the way objects in memory must be allocated according to the underlying architecture. For instance, a machine might expect an int to be aligned upon a 4-byte boundary. If that is the case then a structure with a member int must be aligned upon a 4-byte boundary and the int member offset from that boundary by some multiple of 4 bytes. Consider the following: struct X_ { char c; int i; } X; assert (sizeof(X)==sizeof(int)+sizeof(char)); /* oops */ Assuming sizeof(int) is 4 and sizeof(char) is 1 and that an int must be aligned on a 4-byte boundary, the actual length of this structure must be 8 bytes, not the 5 we expected. If it were anything other than 8, then an array of such structures would have misalignments in 3 out of every 4 elements. Note that in order to correctly align this structure, the compiler must insert 3 padding bytes immediately after the char member. This ensures that the int member is offset 4 bytes from the start of the structure. So long as the structure itself is aligned upon a 4-byte boundary (which it now will be because 8 is a multiple of 4), the int will always be correctly aligned. Inserting padding bytes between members can often increase a structure's size far more than we might expect, particularly if there are many members. To avoid this, it is best to declare members in order of size, largest first. In this way, whenever padding is required, the padding is more likely to be placed at the end of the structure rather than between two or more members. struct X_ { char c; int i; char c2; } X; Given the same criteria as before, this structure would be 12 bytes in length. But by changing the order of the members, we can reduce this to just 8 bytes: struct X_ { int i; char c; char c2; } X; The reason this works is because a char can always be aligned on a 1-byte boundary, so two consecutive char members will easily fit inside a 4-byte word. Thus we only require 2 bytes of padding instead of 4. Note that it is never safe to assume the lengths of any data type in C other than char which is always sizeof(char)==1. The lengths of all other types are measured in terms of a char, but will vary from system to system according to the underlying architecture. Always use the sizeof() operator to determine type lengths. Note that the sizeof() operator computes data type lengths at compile time, so there is no runtime cost, nor is there any need to store the return value.
What rhymes with ar?
bar, car, char, czar, far, gar, jar, mar, par, scar, spar, star, tar, tsar, bazaar, bizarre, cigar, dinar, disbar, guitar, sitarcar, bar, far, gar, jar, mar, par, star, spar, tar, scar, char
11 Determines how far away the data values are from the average?
Standard deviation determines how far away the data values are from the average.
Importance of data structure?
Data structure is important since it dictates the types of operations we can perform on the data and how efficiently they can be carried out. It also dictates how dynamic we can be in dealing with our data; for example it dictates if we can add additional data on the fly or if we need to know about all of the data up front. We determine which data structures to use to store our data only after we've carefully analyzed the problem and know at least what it is we hope to do with the data; for example if we'll require random access, or sequential access, or the ability to move both forward and backward through the data.
