digitalmars.D.learn - string to char conv
- zeus (21/21) Aug 13 2018 i have the following code in d and i get as result 4D77EB, also i
- Jonathan M Davis (6/27) Aug 13 2018 Why are you casting the string to a char*? That's just going to make wri...
- zeus (3/11) Aug 13 2018 Needed char* for while (isspace(*testi)) --testi; etc
- Jonathan M Davis (18/32) Aug 13 2018 Why would you be calling C functions for basic stuff like that? Just use
- Jonathan M Davis (19/62) Aug 13 2018 I suppose that I should point out that you almost never want to use char...
i have the following code in d and i get as result 4D77EB, also i
have the following code in c++ wich give me as results
0xABCDEF123abcdef12345678909832190000011111111 how i can get in d
0xABCDEF123abcdef12345678909832190000011111111 instead of 4D77EB
// D
void test(string test){
char* testi = cast(char*)(test);
writeln(testi);
}
void main()
{
test("0xABCDEF123abcdef12345678909832190000011111111");
}
// C++
void test(string str){
const char* testi = str.c_str();
printf("%s\n", testi);
}
int main(int argc, char const *argv[]){
test("0xABCDEF123abcdef12345678909832190000011111111");
}
Aug 13 2018
On Monday, August 13, 2018 6:06:22 PM MDT zeus via Digitalmars-d-learn
wrote:
i have the following code in d and i get as result 4D77EB, also i
have the following code in c++ wich give me as results
0xABCDEF123abcdef12345678909832190000011111111 how i can get in d
0xABCDEF123abcdef12345678909832190000011111111 instead of 4D77EB
// D
void test(string test){
char* testi = cast(char*)(test);
writeln(testi);
}
void main()
{
test("0xABCDEF123abcdef12345678909832190000011111111");
}
// C++
void test(string str){
const char* testi = str.c_str();
printf("%s\n", testi);
}
int main(int argc, char const *argv[]){
test("0xABCDEF123abcdef12345678909832190000011111111");
}
Why are you casting the string to a char*? That's just going to make writeln
print out the pointer value. If you want to print out the value of the
string, then just pass the string to writeln.
- Jonathan M Davis
Aug 13 2018
On Tuesday, 14 August 2018 at 00:24:53 UTC, Jonathan M Davis wrote:On Monday, August 13, 2018 6:06:22 PM MDT zeus via Digitalmars-d-learn wrote:Needed char* for while (isspace(*testi)) --testi; etc[...]Why are you casting the string to a char*? That's just going to make writeln print out the pointer value. If you want to print out the value of the string, then just pass the string to writeln. - Jonathan M Davis
Aug 13 2018
Jonathan M Davis <newsgroup.d jmdavisprog.com> On Monday, August 13, 2018 6:42:02 PM MDT zeus via Digitalmars-d-learn wrote:On Tuesday, 14 August 2018 at 00:24:53 UTC, Jonathan M Davis wrote:Why would you be calling C functions for basic stuff like that? Just use std.ascii.isWhite (or std.uni.isWhite if you want Unicode whitespace) if you want to check whether a character is whitespace, and there's really no reason to use pointers with D strings. But if you just want to strip the whitespace off of the front of a string, then use std.string.stripLeft. e.g. auto result = str.stripLeft(); Or a more general solution would involve using std.algorithm.searching.find to find a specific character, or a character which matches a predicate. stripLeft is basically a more efficient version of auto result = str.find!(a => !isWhite(a))(); Very little D code is ever going to be doing anything with char* unless it's calling toStringz on a string to pass it to a C function, because there is no D equivalent. Using char* loses the length of the string and loses out on bounds-checking. And since D strings are not zero-terminated, it usually does not work well at all to operate on a char* as if it were a string. - Jonathan M DavisOn Monday, August 13, 2018 6:06:22 PM MDT zeus via Digitalmars-d-learn wrote:Needed char* for while (isspace(*testi)) --testi; etc[...]Why are you casting the string to a char*? That's just going to make writeln print out the pointer value. If you want to print out the value of the string, then just pass the string to writeln. - Jonathan M Davis
Aug 13 2018
On Monday, August 13, 2018 6:24:53 PM MDT Jonathan M Davis via Digitalmars- d-learn wrote:On Monday, August 13, 2018 6:06:22 PM MDT zeus via Digitalmars-d-learn wrote:I suppose that I should point out that you almost never want to use char* in D unless interacting with C or C++. Strings in D are not zero-terminated. They are dynamic arrays of characters. String literals do have a '\0' one past their end so that you can pass string literals to C functions which take const char*, and std.string.toStringz can be used to convert a string to a zero-terminated immutable(char)*, but in general, you just don't use zero-terminated strings in D, and writeln is far more flexible than printf, since it will accept pretty much any type. I'd suggest that you read the documentation for the writeln family of functions: https://dlang.org/phobos/std_stdio.html#.writeln https://dlang.org/phobos/std_stdio.html#.writefln https://dlang.org/phobos/std_stdio.html#.write https://dlang.org/phobos/std_stdio.html#.writef and the documentation for formattedWrite explains the flags accepted by the various functions that accept format strings (e.g. writefln or format): https://dlang.org/phobos/std_format.html#.formattedWrite - Jonathan M Davisi have the following code in d and i get as result 4D77EB, also i have the following code in c++ wich give me as results 0xABCDEF123abcdef12345678909832190000011111111 how i can get in d 0xABCDEF123abcdef12345678909832190000011111111 instead of 4D77EB // D void test(string test){ char* testi = cast(char*)(test); writeln(testi); } void main() { test("0xABCDEF123abcdef12345678909832190000011111111"); } // C++ void test(string str){ const char* testi = str.c_str(); printf("%s\n", testi); } int main(int argc, char const *argv[]){ test("0xABCDEF123abcdef12345678909832190000011111111"); }Why are you casting the string to a char*? That's just going to make writeln print out the pointer value. If you want to print out the value of the string, then just pass the string to writeln.
Aug 13 2018