multiple string literals to const char* in same assignment statement

Question

I'm new to c++ and I came across below code snippet which looks strange for me.

const char* keys = "hello" "world";
std::cout << keys << std::endl;

Above code prints helloworld in the console. Is it syntactically valid to assign two string literals to a const char* in the same statement? if so, how it will be stored in memory?

"hello" "world" == "helloworld"

Melon
– Melon

2019-03-22 08:11:40 +00:00
Commented Mar 22, 2019 at 8:11 — Melon
– Melon, Commented Mar 22, 2019 at 8:11

john · Accepted Answer · 2019-03-22 08:10:46Z

5

It's a rule of C++ (and C) adjacent string literals are concatenated prior to compilation (but after macro expansion IIRC).

This happens anywhere, not just as part of an assignment statement.

answered Mar 22, 2019 at 8:10

john

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2 Comments

Vencat Over a year ago

so the string literals are concatenated prior to compilation and stored contiguously in read only data segment.

john Over a year ago

They're stored contiguously, but using a read only data segment is an implementation detail that won't be true for some systems.

P.W · Accepted Answer · 2019-03-22 08:12:32Z

4

A character sequence within quotes (or even empty quotes) with or without an encoding prefix is a string-literal as per [lex.string].

And as per [lex.string]/13:

...adjacent string-literals are concatenated.

So

const char* keys = "hello" "world";

is same as:

const char* keys = "helloworld";

answered Mar 22, 2019 at 8:12

P.W

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