Question

Given that scanf has (const char *) in the documentation from Microsoft and the answer to this question what the heck is going when I do the same for (char **) promotion to (const char **)?

Basically why does this compile?

#include <stdio.h> int main(int argc, char **argv) {        char szArray[50];     int  i = 0;     strcpy(szArray,'10');     /* the following code is upcasting the (char *) to (const char *) */     sscanf(szArray,'%d',&i);     return 0;   } 

And why won’t this compile?

#include <stdio.h> void processargs(const char **p) {  } int main(int argc, char **argv) {     processargs(argv);               return 0;   } 

Both seem to be doing the same thing to a pointer!

Answer 1

char** -> const char ** is dangerous, since you might end up accidentally modifying the underlying const object.

The correct way to write what you want is:

void processargs(const char * const *p) {  }