Question

The preprocessor can be used to replace certain keywords with other words using #define. For example I could do #define name "George" and every time the preprocessor finds ‘name’ in the program it will replace it with “George”.

However, this only seems to work with code. How could I do this with strings and text? For example if I print “Hello I am name” to the screen, I want ‘name’ to be replaced with “George” even though it is in a string and not code.

I do not want to manually search the string for keywords and then replace them, but instead want to use the preprocessor to just switch the words.

Is this possible? If so how?

I am using C++ but C solutions are also acceptable.

Answer 1

#define name "George"

printf("Hello I am " name "\n");

Adjacent string literals are concatenated in C and C++.

Quotes from C and C++ Standard:

For C (quoting C99, but C11 has something similar in 6.4.5p5):

(C99, 6.4.5p5) “In translation phase 6, the multibyte character sequences specified by any sequence of adjacent character and identically-prefixed string literal tokens are concatenated into a single multibyte character sequence.”

For C++:

(C++11, 2.14.5p13) “In translation phase 6 (2.2), adjacent string literals are concatenated.”

EDIT: as requested, add quotes from C and C++ Standard. Thanks to @MatteoItalia for the C++11 quote.