2 回答
The problem is that the second parameter of execvp
is a char * const *
, which is a "pointer to a constant pointer to non-constant data". You're trying to pass it a const char **
, which is a "pointer to a pointer to constant data".
The way to fix this is to use char **
instead of const char **
(since "pointer to X" is always allowed to be convert to "pointer to const
X", for any type X (but only at the top level of pointers):
char* p[10];
p[0] = ...;
// etc.
Note that if you do need to insert const char *
parameters, you can cast them char *
as long as you don't modify them. Although the arguments to the exec*
family of functions are declared as non-const
, they won't ever modify them (see the POSIX 2008 specification). The rationale there explains why they are declared as non-const
.
You can just use char *p[10]
.
To break it down: char *const *p
means "nonconstant pointer to constant pointer of nonconstant char" -- that is, p
is writable, p[0]
is not writable, and p[0][0]
is writable.