Thread overview | |||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
January 28, 2003 scanf, char*, access violation | ||||
---|---|---|---|---|
| ||||
This compiles correctly: import c.stdio; int main(char[][] args) { char[] a; char[80] b; printf('hey: '); ubyte n=scanf('%s',b); printf('.'); a=b[0..n-1]; printf('%.*s'\n,a); return 0; } But this is the output I get when I run it: hey: hey Error: Access Violation It doesn't pass the scanf(). Why? ------------------------- Carlos Santander http://carlos3.netfirms.com/ --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.449 / Virus Database: 251 - Release Date: 2003-01-27 |
January 28, 2003 Re: scanf, char*, access violation | ||||
---|---|---|---|---|
| ||||
Posted in reply to Carlos Santander B. | "Carlos Santander B." <carlos8294@msn.com> wrote in message news:b16l6l$t8p$1@digitaldaemon.com... > It doesn't pass the scanf(). Why? try this: import c.stdio; int main(char[][] args) { char[] a; char[80] b; printf('hey: '); ubyte n=scanf('%s',&b); printf('.'); a = b; printf("%.*s\n",a); return 0; } |
January 28, 2003 Re: scanf, char*, access violation | ||||
---|---|---|---|---|
| ||||
Posted in reply to Andrew Edwards | "Andrew Edwards" <aedwards@spamfreeamerica.com> escribió en el mensaje news:b16lrf$to4$1@digitaldaemon.com... | "Carlos Santander B." <carlos8294@msn.com> wrote in message | news:b16l6l$t8p$1@digitaldaemon.com... | > It doesn't pass the scanf(). Why? | | try this: | | import c.stdio; | int main(char[][] args) { | char[] a; | char[80] b; | printf('hey: '); | ubyte n=scanf('%s',&b); | printf('.'); | a = b; | printf("%.*s\n",a); | return 0; | } | | Thanks, that worked. I thought that 'char[80] x' was almost like 'char *x'... ————————————————————————— Carlos Santander http://carlos3.netfirms.com/ --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.449 / Virus Database: 251 - Release Date: 2003-01-27 |
January 28, 2003 Re: scanf, char*, access violation | ||||
---|---|---|---|---|
| ||||
Posted in reply to Andrew Edwards | "Andrew Edwards" <aedwards@spamfreeamerica.com> escribió en el mensaje news:b16lrf$to4$1@digitaldaemon.com... | "Carlos Santander B." <carlos8294@msn.com> wrote in message | news:b16l6l$t8p$1@digitaldaemon.com... | > It doesn't pass the scanf(). Why? | | try this: | | import c.stdio; | int main(char[][] args) { | char[] a; | char[80] b; | printf('hey: '); | ubyte n=scanf('%s',&b); | printf('.'); | a = b; | printf("%.*s\n",a); | return 0; | } | | Actually, it doesn't work. I hadn't checked, but when I printf 'b', it doesn't print what I wrote. ————————————————————————— Carlos Santander http://carlos3.netfirms.com/ --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.449 / Virus Database: 251 - Release Date: 2003-01-27 |
January 28, 2003 Re: scanf, char*, access violation | ||||
---|---|---|---|---|
| ||||
Posted in reply to Carlos Santander B. | > Actually, it doesn't work. I hadn't checked, but when I printf 'b', it doesn't print what I wrote.
>
b is similar to a C or C++ array, to access its content you use a loop. D is simpler though, you can type this
printf("%.*s\n", b[0 .. b.length]);
your approach printf("%.*s\n", b) passes the address of the first memory
location to printf and is therefore analagous to printf("%.*s\n", b[0]); "A
request to print the first character of the array."
|
January 29, 2003 Re: scanf, char*, access violation | ||||
---|---|---|---|---|
| ||||
Posted in reply to Andrew Edwards | "Andrew Edwards" <aedwards@spamfreeamerica.com> escribió en el mensaje news:b16lrf$to4$1@digitaldaemon.com... | "Carlos Santander B." <carlos8294@msn.com> wrote in message | news:b16l6l$t8p$1@digitaldaemon.com... | > It doesn't pass the scanf(). Why? | | try this: | | import c.stdio; | int main(char[][] args) { | char[] a; | char[80] b; | printf('hey: '); | ubyte n=scanf('%s',&b); | printf('.'); | a = b; | printf("%.*s\n",a); | return 0; | } | | After trying a lot without any success, I was forced to write my own function, and read a 'char[]' char by char. ————————————————————————— Carlos Santander http://carlos3.netfirms.com/ --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.449 / Virus Database: 251 - Release Date: 2003-01-27 |
January 29, 2003 Re: scanf, char*, access violation | ||||
---|---|---|---|---|
| ||||
Posted in reply to Carlos Santander B. | Carlos Santander B. wrote:
> "Andrew Edwards" <aedwards@spamfreeamerica.com> escribió en el mensaje
> news:b16lrf$to4$1@digitaldaemon.com...
> | "Carlos Santander B." <carlos8294@msn.com> wrote in message
> | news:b16l6l$t8p$1@digitaldaemon.com...
> | > It doesn't pass the scanf(). Why?
> |
> | try this:
> |
> | import c.stdio;
> | int main(char[][] args) {
> | char[] a;
> | char[80] b;
> | printf('hey: ');
> | ubyte n=scanf('%s',&b);
> | printf('.');
> | a = b;
> | printf("%.*s\n",a);
> | return 0;
> | }
> |
> |
>
> After trying a lot without any success, I was forced to write my own
> function, and read a 'char[]' char by char.
You don't need that. What's happening is that D arrays have both a length and a pointer, even when they have static length, so you just need to cast it to a pointer to get rid of that:
scanf ("%s", (char *) b);
Another thing. The line:
a = b;
Won't have the effect you want; "a" will have a length of 80. Use:
import string;
...
a = string.toString ((char *) b);
Instead.
|
January 29, 2003 Re: scanf, char*, access violation | ||||
---|---|---|---|---|
| ||||
Posted in reply to Burton Radons | "Burton Radons" <loth@users.sourceforge.net> escribió en el mensaje news:b17f4s$7a0$1@digitaldaemon.com... | | You don't need that. What's happening is that D arrays have both a | length and a pointer, even when they have static length, so you just | need to cast it to a pointer to get rid of that: | | scanf ("%s", (char *) b); | I also tried that. | Another thing. The line: | | a = b; I'm not doing that... | | Won't have the effect you want; "a" will have a length of 80. Use: | | import string; | | ... | a = string.toString ((char *) b); | | Instead. | ... I do this: a=b[0..strlen(b)-1]; ------------------------- Carlos Santander http://carlos3.netfirms.com/ --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.449 / Virus Database: 251 - Release Date: 2003-01-27 |
January 29, 2003 Re: scanf, char*, access violation | ||||
---|---|---|---|---|
| ||||
Posted in reply to Carlos Santander B. | This whole problem makes me believe that there should be a direct way to read char[] from the console. It has been requested before, and I think Pavel got scanf() to read that (not sure, though), but DMD should include it. ————————————————————————— Carlos Santander http://carlos3.netfirms.com/ --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.449 / Virus Database: 251 - Release Date: 2003-01-27 |
January 29, 2003 Re: scanf, char*, access violation | ||||
---|---|---|---|---|
| ||||
Posted in reply to Carlos Santander B. | Carlos Santander B. wrote: > "Burton Radons" <loth@users.sourceforge.net> escribió en el mensaje > news:b17f4s$7a0$1@digitaldaemon.com... > | > | You don't need that. What's happening is that D arrays have both a > | length and a pointer, even when they have static length, so you just > | need to cast it to a pointer to get rid of that: > | > | scanf ("%s", (char *) b); > | > > I also tried that. No you didn't, or you had bad code at another part of the program. > | Won't have the effect you want; "a" will have a length of 80. Use: > | > | import string; > | > | ... > | a = string.toString ((char *) b); > | > | Instead. > | > > ... I do this: a=b[0..strlen(b)-1]; This will lop off the last byte; slice parameters aren't inclusive. Here's your code, corrected: import c.stdio, string; void main() { char[] a; char[80] b; printf('hey: '); scanf('%s',(char*)b); printf('.'); a=toString(b); printf('%.*s'\n,a); } |
Copyright © 1999-2021 by the D Language Foundation