%20and%20varying(4)%20character%20data%20to%20the%20IFS%20stream%20file%20in%20RPGLE.png "Writing varying(2) and varying(4) character data to the IFS stream file in RPGLE") |
| Writing varying(2) and varying(4) character data to the IFS stream file in RPGLE |
Varying(2) and varying(4) are default values which are pre-assumed by the system, if we do not provide 2 and 4 it is considered by the system itself depending upon the length of the character data.
Differentiate between varying(2) and varying (4) character data in RPGLE
Varying keyword used while defining character variable to denote the variable is a varying length variable not a fixed format. Let's take an example to understand.
Varying(2) character fields
Difsdata s 20a inz('TEST')
Here, we defined standalone character field ifsdata of fixed length 20. This field will always have the length of 20 irrespective of the data it contains.
Difsdata s 20a inz('TEST') varying
or
Difsdata s 20a inz('TEST') varying(2)
Here, we defined standalone character field ifsdata of varying length 20. This field will have the length as per the data contained in it. Therefore, this field has actual length 4. We can either defined varying or varying(2) both are acceptable. If we only defined Varying the compiler assumed it to varying(2) if the variable length is from 1 to 65535.
The two bytes appended to this varying(2) length field at the start that contains the length of this field as per the length of the data contained within it.
Varying(4) character fields
Difsdata s 123520a inz('TEST')
Here, we defined standalone character field ifsdata of fixed length 123520. This field will always have the length of 123520a irrespective of the data it contains.
Difsdata s 123520a inz('TEST') varying
or
Difsdata s 123520a inz('TEST') varying(4)
Here, we defined standalone character field ifsdata of varying length 123520. This field will have the length as per the data contained in it. Therefore, this field has actual length 4. We can either defined varying or varying(4) both are acceptable. If we only defined Varying the compiler assumed it to varying(4) if the variable length is from greater than 65535.
The four bytes appended to this varying(4) length field at the start that contains the length of this field as per the length of the data contained within it.
Write char Varying(2) data to IFS in RPGLE
Here we are referring to the same program mentioned in Handling Errors while working with IFS stream file using RPGLE. We will only change the definition of the field ifsdata and write() procedure call. I am not writing all the Fixed and Fully free code here that you can refer from the link mentioned above. I am highlighting the change which i am doing to the code which is mentioned and explained in above link.
D errorifs PR * ExtProc('__errno')
D strerror PR * ExtProc('strerror')
D error_num 10I 0 value
D close PR 10i 0 extproc('close') *
D fileds 10i 0 value *file descriptor
D write PR 10i 0 extproc('write') * 32 bit, no. of byt
D fileds 10i 0 value *file descriptor
D buffer * value * pointer to byte
D noofbytes 10U 0 value * 32 bits
D open PR 10I 0 extproc('open')
D ifspath * value options(*string) *ifs path
D oflag 10I 0 value *string of 32 bits
D mode 10U 0 value options(*nopass) * 9 bits
D codepage 10U 0 value options(*nopass) *
* <-----oflag---->
D O_readonly C 1
D O_writeonly C 2
D O_readwrite C 4
D O_createfileifnotexist...
D C 8
D O_exclusivecreate...
D C 16
D O_truncateto0bytes...
D C 64
D O_appendtofile C 256
D O_converttextbycodepage...
D C 8388608
D O_openintextmode...
D C 16777216
*
* <-----mode---->
* owner,group,other (RWX)
* owner authority
D M_readowner C 256
D M_writeowner C 128
D M_executeowner C 64
* group authority
D M_readgroup C 32
D M_writegroup C 16
D M_executegroup C 8
* other people
D M_readother C 4
D M_writeother C 2
D M_executeother C 1
*
Difspath s 512a
Doflag s 10I 0
Dmode s 10U 0
Dcodepage s 10U 0
Dfiledescriptor s 10i 0
Difsdata s 65535a inz varying(2)
Dreturn_write s 10i 0 inz
Dreturn_close s 10i 0 inz
Derror_ptr S *
Derror_num S 10I 0 based(error_ptr)
Derrormsg_ptr S *
Derror_msg S 500a based(errormsg_ptr)
/free
ifspath = '/home/easyclass/helloworld';
oflag = O_writeonly +
O_createfileifnotexist;
mode =
M_readowner +
M_writeowner +
M_executeowner;
filedescriptor = open(%trim(ifspath):
oflag:
mode);
if filedescriptor < 0;
error_ptr = errorIFS();
errormsg_ptr = strerror(error_num);
return;
endif;
ifsdata = 'HELLO WORLD';
// explanation of below highlighted
// we are passing address of ifsdata variable and adding 2 bytes to the address i.e.
// start reading by shifting right to the 2 bytes from the start
// of the address since first 2 bytes contained length of the variable ifsdata.
return_write = write(filedescriptor:%addr(ifsdata)+2:%size(ifsdata));
if return_write < %size(ifsdata);
error_ptr = errorIFS();
errormsg_ptr = strerror(error_num);
return;
endif;
return_close = close(filedescriptor);
if return_close = -1;
error_ptr = errorIFS();
errormsg_ptr = strerror(error_num);
return;
endif;
*inlr = *on;
return;
/end-free
Write char Varying(4) data to IFS in RPGLE
Here we are referring to the same program mentioned in Handling Errors while working with IFS stream file using RPGLE. We will only change the definition of the field ifsdata and write() procedure call. I am not writing all the Fixed and Fully free code here that you can refer from the link mentioned above. I am highlighting the change which i am doing to the code which is mentioned and explained in above link.
* varying(2) --> 1 -65535
* varying(4) --> >65535
D errorifs PR * ExtProc('__errno')
D strerror PR * ExtProc('strerror')
D error_num 10I 0 value
D close PR 10i 0 extproc('close') *
D fileds 10i 0 value *file descriptor
D write PR 10i 0 extproc('write') * 32 bit, no. of byt
D fileds 10i 0 value *file descriptor
D buffer * value * pointer to byte
D noofbytes 10U 0 value * 32 bits
D open PR 10I 0 extproc('open')
D ifspath * value options(*string) *ifs path
D oflag 10I 0 value *string of 32 bits
D mode 10U 0 value options(*nopass) * 9 bits
D codepage 10U 0 value options(*nopass) *
* <-----oflag---->
D O_readonly C 1
D O_writeonly C 2
D O_readwrite C 4
D O_createfileifnotexist...
D C 8
D O_exclusivecreate...
D C 16
D O_truncateto0bytes...
D C 64
D O_appendtofile C 256
D O_converttextbycodepage...
D C 8388608
D O_openintextmode...
D C 16777216
*
* <-----mode---->
* owner,group,other (RWX)
* owner authority
D M_readowner C 256
D M_writeowner C 128
D M_executeowner C 64
* group authority
D M_readgroup C 32
D M_writegroup C 16
D M_executegroup C 8
* other people
D M_readother C 4
D M_writeother C 2
D M_executeother C 1
*
Difspath s 512a
Doflag s 10I 0
Dmode s 10U 0
Dcodepage s 10U 0
Dfiledescriptor s 10i 0
Difsdata s 65536a inz varying(4)
Dreturn_write s 10i 0 inz
Dreturn_close s 10i 0 inz
Derror_ptr S *
Derror_num S 10I 0 based(error_ptr)
Derrormsg_ptr S *
Derror_msg S 500a based(errormsg_ptr)
/free
ifspath = '/home/easyclass/helloworld';
oflag = O_writeonly +
O_createfileifnotexist;
mode =
M_readowner +
M_writeowner +
M_executeowner;
filedescriptor = open(%trim(ifspath):
oflag:
mode);
if filedescriptor < 0;
error_ptr = errorIFS();
errormsg_ptr = strerror(error_num);
return;
endif;
ifsdata = 'HELLO WORLD';
// explanation of below highlighted
// we are passing address of ifsdata variable and adding 4 bytes to the address i.e.
// start reading by shifting right to the 4 bytes from the start
// of the address since first 4 bytes contained length of the variable ifsdata.
return_write = write(filedescriptor:%addr(ifsdata)+4:%size(ifsdata));
if return_write < %size(ifsdata);
error_ptr = errorIFS();
errormsg_ptr = strerror(error_num);
return;
endif;
return_close = close(filedescriptor);
if return_close = -1;
error_ptr = errorIFS();
errormsg_ptr = strerror(error_num);
return;
endif;
*inlr = *on;
return;
/end-free