NSMutableString getCString misbehaves, does not show some characters

Question

Hi everyone,
This is my first time here.
I have written a small tool for Cocoa / MacOSX 10.5 and I am trying to save a text to a file, but some characters such as # appear as hex 0x0.
Source: -----
int len = [results length] * sizeof(char);
char *buffer = malloc(len);
[results getCString: buffer maxLength: len-1 encoding: NSWindowsCP1250StringEncoding];
NSData *dt = [NSData dataWithBytes: buffer length: len];
[fileManager createFileAtPath: @"/Volumes/MacBackup/results.sh" contents: dt attributes:nil];
The # and the final 2-3 characters appear as 0x0 in a hex viewer. I have tried almost all encodings, but to no avail. Can anyone tell me how to make it work? Do I have to enter the # directly in the char buffer as ASCII char or am I missing something about the encoder?
Btw, I am a newb at Mac programming, but I come from a solid Windows programming background, but please don't hold that against me :P.
Message was edited by: TTDeath
Message was edited by: TTDeath

Answer 1

Hi TT, and welcome to the Dev Forum!
TTDeath wrote:
I have written a small tool for Cocoa / MacOSX 10.5 and I am trying to save a text to a file, but some characters such as # appear as hex 0x0.
int len = [results length] * sizeof(char); // <-- need to add one here
char *buffer = malloc(len);
The NSString length method doesn't count a terminator; i.e. it's analogous to strlen(), so if you convert an ASCII C string to a NSString object, the return from [results length] will be the same as strlen(source). I'm not sure there wasn't something else going on at your end, since this length error only strips the trailing char from the source string. In any case, the following code should work for you:
// made from MAC OS X->Command Line Utility->Foundation Tool template
#import <Foundation/Foundation.h>
int main (int argc, const char * argv[]) {
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
// insert code here...
NSLog(@"Hello, World!");
NSString *results = @"A string with # embedded
int len = [results length] * sizeof(char) + 1; // <--
char *buffer = malloc(len);
BOOL bError = [results getCString: buffer
maxLength: len encoding: NSWindowsCP1250StringEncoding];
NSLog(@"getCString returns %d", bError);
NSData *dt = [NSData dataWithBytes: buffer length: len];
NSLog(@"dt=%@", dt);
NSFileManager *fileManager = [NSFileManager defaultManager];
// I don't recommend testing in a system directory -
// remember to substitute your home dir name here:
bError = [fileManager createFileAtPath: @"/Users/Ray/results.sh"
contents: dt attributes:nil];
NSLog(@"createFileAtPath returns %d", bError);
[pool drain];
return 0;
// [Session started at 2009-12-05 16:47:41 -0800.]
// 2009-12-05 16:47:41.045 TT[463:10b] Hello, World!
// 2009-12-05 16:47:41.048 TT[463:10b] getCString returns 1
// 2009-12-05 16:47:41.049 TT[463:10b] dt=<41207374 72696e67
// 20776974 68202320 656d6265 64646564 0a00>
// 2009-12-05 16:47:41.054 TT[463:10b] createFileAtPath returns 1
// rays-imac:~ Ray$ cat results.sh
// A string with # embedded
- Ray