Immediate arrays

[Paul N]

Is there a way to have an array temporarily without giving it a name?
For instance, can you do something along the lines of:

char *str;

str = { "Tom", "Dick", "Harry" } [2];

Many thanks.
Paul.

 

[Victor Bazarov]

Is there a way to have an array temporarily without giving it a name?
For instance, can you do something along the lines of:

char *str;

str = { "Tom", "Dick", "Harry" } [2];

No. Why would you need that? Why not simply

const char* str;
...
str = "Harry";

?

V

 

[SG]

Is there a way to have an array temporarily without giving it a name?
For instance, can you do something along the lines of:

char *str;

str = { "Tom", "Dick", "Harry" } [2];

char const* func(unsigned index) {
assert(index<3);
return "Tom\0 "
"Dick\0"
"Harry"+(index*5);
}



But seriously, don't do that.

Cheers!
SG

 

[Andrey Tarasevich]

Is there a way to have an array temporarily without giving it a name?
For instance, can you do something along the lines of:

char *str;

str = { "Tom", "Dick", "Harry" } [2];

The feature exists in C99 version of C, but not in standard C++

// C99 compound literal
const char *str = (const char*[]) { "Tom", "Dick", "Harry" } [2];

So, your only hope is that your compiler borrows it from C as an extension.

 

[Johannes Schaub]

Is there a way to have an array temporarily without giving it a name?
For instance, can you do something along the lines of:

char *str;

str = { "Tom", "Dick", "Harry" } [2];

Yes, but you need a utility first to create it on demand:

template<typename T> using id = T;

So then it looks natural

str = id<char const*[]>{"Tom", "Dick", "Harry"}[2];

Hope it helps.

 

[Johannes Schaub]

Is there a way to have an array temporarily without giving it a name?
For instance, can you do something along the lines of:

char *str;

str = { "Tom", "Dick", "Harry" } [2];

Yes, but you need a utility first to create it on demand:

template<typename T> using id = T;

So then it looks natural

str = id<char const*[]>{"Tom", "Dick", "Harry"}[2];

Hope it helps.

But note: as the array is a temporary, the pointer "str" will point to
unallocated memory after that assignment expression has been evaluated,
because at the end of a full expression, all temporaries not directly bound
by references will be destroyed.

 

[SG]

Yes, but you need a utility first to create it on demand:
    template<typename T> using id = T;
So then it looks natural
    str = id<char const*[]>{"Tom", "Dick", "Harry"}[2];
Hope it helps.

But note: as the array is a temporary, the pointer "str" will point to
unallocated memory after that assignment expression has been evaluated,

I don't think so. The array of pointers will vanish, but the arrays of
characters will stay. string literals are stored in static memory, are
they not?

SG

 

[Johannes Schaub]

Yes, but you need a utility first to create it on demand:
template<typename T> using id = T;
So then it looks natural
str = id<char const*[]>{"Tom", "Dick", "Harry"}[2];
Hope it helps.

But note: as the array is a temporary, the pointer "str" will point to
unallocated memory after that assignment expression has been evaluated,

I don't think so. The array of pointers will vanish, but the arrays of
characters will stay. string literals are stored in static memory, are
they not?

Yes, it was my mistake. What you say is right. I canceled the above note a
few minutes after I sent the message, but apparently it wasn't removed from
all usenet servers.