WRITEFILE: Difference between revisions
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(Created page with "{{DISPLAYTITLE: _WRITEFILE}} The '''_WRITEFILE''' function writes a string into a new file, overwriting an existing file of the same name. It does OPEN, PUT and CLOSE the file in one run. It's the counterpart to _READFILE$. {{PageSyntax}} : {{Parameter|success%}} = _WRITEFILE({{Parameter|fileSpec$}}, {{Parameter|contents$}}) {{PageParameters}} * {{Parameter|success%}} is an INTEGER return value, it shows whether the write operation was success...") |
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{{PageParameters}} | {{PageParameters}} | ||
* {{Parameter|success%}} is an [[INTEGER]] return value, it shows whether the write operation was successful (-1) or not (0). Any file related [[ERROR Codes|ERROR]] may occur. | * {{Parameter|success%}} is an [[INTEGER]] return value, it shows whether the write operation was successful (-1) or not (0). Any file related [[ERROR Codes|ERROR]] may occur. | ||
** To avoid errors you should use [[ | ** To avoid errors you should use [[_DIREXISTS]] before calling this function to make sure a used path exists. | ||
* {{Parameter|fileSpec$}} is the name of the file to write as literal or variable [[STRING]], if required inclusive a full or relative path. | * {{Parameter|fileSpec$}} is the name of the file to write as literal or variable [[STRING]], if required inclusive a full or relative path. | ||
* {{Parameter|contents$}} is the literal or variable [[STRING]] which its contents shall be written into the file. | * {{Parameter|contents$}} is the literal or variable [[STRING]] which its contents shall be written into the file. | ||
Revision as of 23:53, 15 February 2024
The _WRITEFILE function writes a string into a new file, overwriting an existing file of the same name. It does OPEN, PUT and CLOSE the file in one run. It's the counterpart to _READFILE$.
Syntax
- success% = _WRITEFILE(fileSpec$, contents$)
Parameters
- success% is an INTEGER return value, it shows whether the write operation was successful (-1) or not (0). Any file related ERROR may occur.
- To avoid errors you should use _DIREXISTS before calling this function to make sure a used path exists.
- fileSpec$ is the name of the file to write as literal or variable STRING, if required inclusive a full or relative path.
- contents$ is the literal or variable STRING which its contents shall be written into the file.
Description
- Sometimes you may be in need to quickly dump a huge amount of data into a file without much fuss, e.g. the results of the pack/unpack functions _DEFLATE$ and _INFLATE$ or when copying a file in conjunction with the _READFILE$ function.
- In earlier versions of QB64(PE) you had to implement that saving process manually all the time or create a reusable custom FUNCTION for it.
- Now _WRITEFILE will simplify this, it's mainly a convenience function to wrap the following code sequence in one handy function:
fh = FREEFILE OPEN fileSpec$ FOR OUTPUT AS #fh: CLOSE #fh OPEN fileSpec$ FOR BINARY AS #fh PUT #fh, , contents$ CLOSE #fh |
Availability
none
v3.12.0
yes
yes
yes
Examples
- Example
- Implementing a simple file copy routine using _READFILE$ and _WRITEFILE.
s$ = "Makefile" d$ = "Makefile - Copy" r$ = CopyFile$(s$, d$) IF r$ = "" THEN PRINT "Sucessfully copied '"; s$; "' to '"; d$; "'." ELSE PRINT r$ END IF END FUNCTION CopyFile$ (src$, dst$) CopyFile$ = "" 'empty = success, otherwise error message buffer$ = _READFILE$(src$) IF buffer$ = "" AND _FILEEXISTS(src$) = 0 THEN CopyFile$ = "ERROR: Source file doesn't exist." ELSE succ% = _WRITEFILE(dst$, buffer$) IF NOT succ% THEN CopyFile$ = "ERROR: Couldn't write destination file." END IF END IF END FUNCTION |
See also