No. of strings in format string specifier

Question

I have seen this way of using combination of strings in printf and scanf statements.

int a;
printf("Printing" "using" "multiple" "strings" "%d", a);
// The above is just an example, some usage that I saw was for printing specific integer types like int_32
// uint32_t var; printf("Value is %" PRTu32, var);

I always thought that we could only use a single string as a format specifier. Like as written in the definition of printf function it seems format can point to only one string.

int printf ( const char * format, ... );

So out of curiosity I tried the following code and it ran successfully!

char arr[] = "Hello " "World";
printf("%s",arr);      // Output - Hello World

Could anyone explain how this concatenation thing works and what is the correct way of doing it. Any help is appreciated.

Concatenation works like concatenation! The compiler sees `"foo" "bar"` and treats it the same as `"foobar"`. — William Pursell, Jan 25 '22 at 15:22
See 5.1.1.2 of https://port70.net/~nsz/c/c11/n1570.html#5.1.1.2. "Adjacent string literal tokens are concatenated." — William Pursell, Jan 25 '22 at 15:23

score 0 · Accepted Answer · answered Jan 25 '22 at 15:25

If you give a space or no space in between two string literals it concatenates the string literals.

That's one of the C feature: This is defined by the ISO C standard, adjacent string literals are automatically combined/concatinated into a single one.

No. of strings in format string specifier

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