Is there an equivalent in D for C function "strstr" that return the first occurrence of a given string within another string?

https://en.cppreference.com/w/c/string/byte/strstr

On Friday, 29 July 2022 at 11:23:55 UTC, pascal111 wrote:

https://dlang.org/library/std/string/index_of.html

I never want to break your fervour. But D has what you've been asking for a few days, or even better. Because we have a strong type like immutable(char[]). In summary, it only took me 1 minute to compile the same code:

// D 2.0.83
import std.string;
import std.stdio;

void find_str(string str, string substr)
{
    import std.typecons : No;
    auto pos = indexOf(str, substr, No.caseSensitive);
    if(pos) {
        writef("found the string '%s' in '%s' at position: %s\n", substr, str, pos);
    } else {
        writef("the string '%s' was not found in '%s'\n", substr, str);
    }
}

int main()
{
    string str = "one two three";
    find_str(str, "two");
    find_str(str, "");
    find_str(str, "nine");
    find_str(str, "n");

    return 0;
}

Search and you will definitely find it. If you can't find it, D handles this kind of thing anyway.

SDB@79

Short version:

import std.string;
import std.stdio;

void find (string str, string substr) {
    if(auto pos = str.indexOf(substr)) {
        writefln("found the string '%s' in '%s' at position: %s", substr, str, pos);
    } else {
        writefln("the string '%s' was not found in '%s'", substr, str);
    }
}

void main() {
    string str = "one two three";
    str.find("two");
    str.find("");
    str.find("nine");
    str.find("n");
}

SDB@79

On Friday, 29 July 2022 at 13:44:47 UTC, Salih Dincer wrote:

import std.string;
import std.stdio;

void find (string str, string substr) {
    if(auto pos = str.indexOf(substr)) {
        writefln("found the string '%s' in '%s' at position: %s", substr, str, pos);
    } else {
        writefln("the string '%s' was not found in '%s'", substr, str);
    }
}

void main() {
    string str = "one two three";
    str.find("two");
    str.find("");
    str.find("nine");
    str.find("n");
}

Ok! I have a problem now in understanding these new syntax. You said "str.indexOf(substr)", so I can say that the first parameter of "indexOf" is "str" itself, and second parameter is "substr" and rather than writing it in the form "indexOf(str, substr)" you written it like "str.indexOf(substr)", am I right? and if I'm right, with returning back to the definitions of "indexOf" @ https://dlang.org/phobos/std_string.html#.indexOf we won't find that there is a definition for it with just two parameters, so from where you got this new definition of this function?!

On Friday, 29 July 2022 at 14:14:54 UTC, pascal111 wrote:

If you scroll down further, you will see that there is a second set of overloads for indexOf: https://dlang.org/phobos/std_string.html#.indexOf.2

The reason there are two sets of overloads, with separate documentation, is that one set searches for a single character in a string, while the other set searches for a substring in a string.

On Friday, 29 July 2022 at 14:14:54 UTC, pascal111 wrote:

This thread is about UFCS. It can also be written as:

import std.string,
       std.stdio;

void findStr(string str) { }

void main()
{
  string str = "Hello, World!";
  str.indexOf("Wo").writeln; //7
  auto pos = "Hello, World!".indexOf("Wo");

  auto slice = str[pos..$-1];
  slice.writeln(": ", slice.length); // World: 5
  typeid(slice).writeln; // immutable(char)[]

  assert(str.indexOf("Wo") == pos);

  void find_str(string str) { }

  find_str(str);
  str.findStr();

  /* No compile:

  slice.typeid().writeln;

  slice.indedOf("Wo").assert();

  str.find_str();
  */
}

SDB@79

On Friday, 29 July 2022 at 15:39:16 UTC, Salih Dincer wrote:

import std.string,
       std.stdio;

void findStr(string str) { }

void main()
{
  string str = "Hello, World!";
  str.indexOf("Wo").writeln; //7
  auto pos = "Hello, World!".indexOf("Wo");

  auto slice = str[pos..$-1];
  slice.writeln(": ", slice.length); // World: 5
  typeid(slice).writeln; // immutable(char)[]

  assert(str.indexOf("Wo") == pos);

  void find_str(string str) { }

  find_str(str);
  str.findStr();

  /* No compile:

  slice.typeid().writeln;

  slice.indedOf("Wo").assert();

  str.find_str();
  */
}

I made this version:

auto d_strstr (const string ch, const string substr)
{

    return ch.indexOf(substr);

}

https://github.com/pascal111-fra/D/blob/main/dcollect.d

////////////testing program

module main;

import std.stdio;
import std.string;
import std.conv;
import dcollect;
import std.math;

int main(string[] args)
{
    int x;
    char[] ch;
    string ch1="Hello World!";

    writeln(ch1.d_strstr("ll"));


	return 0;
}