c - Does the preprocessor prepare a list of unique constant strings before the compiler goes into action? -


in code below, have 2 different local char* variables declared in 2 different functions.

each variable initialized point constant string, , contents of 2 strings identical.

checking in runtime, variables initialized point same address in memory.

so compiler must have assigned same (constant) value each 1 of them.

how possible?

#include <stdio.h>  void printpointer() {     char* p = "abc";     printf("%p\n",p); }  int main() {     char* p = "abc";     printf("%p\n",p);     printpointer();     return 0; }

it has nothing preprocessor. compiler explicitly allowed (not required) standard share memory identical string literals. details on when happens, must consult compiler's documentation.

for example, here's relevant documentation vc2013:

in cases, identical string literals may pooled save space in executable file. in string-literal pooling, compiler causes references particular string literal point same location in memory, instead of having each reference point separate instance of string literal. enable string pooling, use /gf compiler option.


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