here is my count char program:

import std.stdio;
import std.string;

void main()
{
     char* s;
     char string[100];

writef("please input your text=");
scanf("%s",&string);
writef("your text length is=",string.length);
}

does my program work properly?. when i try to run it, d compiler tell that
can't convert string to int. please show me the way to convert string into integer. (if you don't mind i need your correction in my simple char program). thank you very much...GBU

import std.stdio : readln, writef, writefln;

void main()
{
    writef("Please input your text: ");
    auto s = readln();
    writefln("Your text length is: %s", s.length);
}

Note that strings in D are *not* NUL-terminated like they are in C. Your code wouldn't work since the .length of a char[100] is *always* 100.  The following is untested, but should work:

import std.string : toString;

void main()
{
    char[100] c_string_buffer;
    scanf("%s", c_string_buffer.ptr);
    auto d_string = toString(c_string_buffer.ptr);
}

.ptr gives you a pointer to an array's first element, so (char[100]).ptr
is a char*.

In this case, toString(char*) assumes its argument is a C-style NUL-terminated string, and converts it to a D string.  Note that it will return a slice of the input data, so that in this particular case, d_string must not outlive c_string_buffer.

	-- Daniel

On Tue, 19 Jun 2007 21:48:06 -0400, pieter Valdano pattiruhu wrote:

> here is my count char program:
> 
> import std.stdio;
> import std.string;
> 
> void main()
> {
>      char* s;
>      char string[100];
> 
> writef("please input your text=");
> scanf("%s",&string);
> writef("your text length is=",string.length);
> }

The main problem is that you are trying to write D as if it was C. There are large differences that make D coding a whole lot easier.

For example, here is a way of doing it :

  import std.stdio;

  void main()
  {
    char[] s;

    writef("please input your text=");
    s = readln();
    writef("your text length is=",s.length);
  }

The differences are that D can use a variable-length array rather than a fixed-length one that one typically uses in C. Also in D, it is rare to use pointers such as 'char *p' because it knows a lot more about arrays and pointer usage than C does, which means you don't have to code as much.

Note that when readln() runs, it collects all the characters typed including the Return/Enter key so that the last character in the buffer is always '\n'.


-- 
Derek
(skype: derek.j.parnell)
Melbourne, Australia
20/06/2007 12:13:29 PM

Daniel Keep Wrote:

> 
> import std.stdio : readln, writef, writefln;
> 
> void main()
> {
>     writef("Please input your text: ");
>     auto s = readln();
>     writefln("Your text length is: %s", s.length);
> }
> 
> Note that strings in D are *not* NUL-terminated like they are in C. Your code wouldn't work since the .length of a char[100] is *always* 100.  The following is untested, but should work:
> 
> import std.string : toString;
> 
> void main()
> {
>     char[100] c_string_buffer;
>     scanf("%s", c_string_buffer.ptr);
>     auto d_string = toString(c_string_buffer.ptr);
> }
> 
> .ptr gives you a pointer to an array's first element, so (char[100]).ptr
> is a char*.
> 
> In this case, toString(char*) assumes its argument is a C-style NUL-terminated string, and converts it to a D string.  Note that it will return a slice of the input data, so that in this particular case, d_string must not outlive c_string_buffer.
> 
> 	-- Daniel

thank you very much mr.daniel...God Bless U

It's really bad to teach someone write buffer overflow vulnerable code

>
> import std.stdio : readln, writef, writefln;
>
> void main()
> {
>     writef("Please input your text: ");
>     auto s = readln();
>     writefln("Your text length is: %s", s.length);
> }
>
> Note that strings in D are *not* NUL-terminated like they are in C.
> Your code wouldn't work since the .length of a char[100] is *always*
> 100.  The following is untested, but should work:
>
> import std.string : toString;
>
> void main()
> {
>     char[100] c_string_buffer;
>     scanf("%s", c_string_buffer.ptr);
>     auto d_string = toString(c_string_buffer.ptr);
> }
>
> .ptr gives you a pointer to an array's first element, so (char[100]).ptr
> is a char*.
>
> In this case, toString(char*) assumes its argument is a C-style
> NUL-terminated string, and converts it to a D string.  Note that it will
> return a slice of the input data, so that in this particular case,
> d_string must not outlive c_string_buffer.
>
> 	-- Daniel



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