Multiple macro string concatenation in C

Before making a concatenation of two strings, the STRCAT function is generally used, even if it is a macro-defined string.

For example, the definition of macro A, B, the first reaction will use A "other" such splicing method, but will not be unresponsive to a B can also do stitching.

The foundation is not solid, good two good two.

The macro string can be spliced like this:

#define a "xxx"
#define B "YYY"

void Main ()
{
    char* str = a b;
    printf ("Str:  %s\n", str);
}

Compiled to run, the output is xxxyyy.

The reason is that C has this syntax: the string of quotes, separated by spaces in the middle, the compiler (preprocessor) will automatically help you into one.

That is, if there are macros A, B, C, D, that char* Str=a b c D; This is also possible.

This principle can also be applied to long string definitions, such as:

#include <stdio.h>

void Main ()
{
    char* sql = "SELECT name"
                "from table1"
                "where xxx=111"; c12/>printf ("sql:  %s\n", SQL);

Compilation runs, the output sql:select name from table1 where xxx=111.