c++ - undeclared identifier using arrayfire -

i write function using arrayfire that:

int abc() {  static const int q = 5; double a[]  = { 0.0,  1.0,  0.0, 1.0, 1.0}; double b[]  = { 0.0, -1.0, -1.0, 1.0, 0.0 }; array c (q, 1, a); array d (q, 1, b);  return 0; } 

when try call function as: abc() in main program , try extract variables c , d , want print them using af_print(c), gives error:

error c2065: 'c' : undeclared identifier error c2065: 'd' : undeclared identifier intellisense: identifier "c" undefined intellisense: identifier "d" undefined 

the main function is:

#include <cstdio> #include <math.h> #include <cstdlib> #include "test.h"  // test.h contains function abc() ,  // arrayfire.h ,  // using namespace af;   int main(int argc, char *argv[])  { abc(); // function // here calling variables defined in abc() af_print(c); af_print(d); #ifdef win32 // pause in windows if (!(argc == 2 && argv[1][0] == '-')) {     printf("hit [enter]...");     fflush(stdout);     getchar(); } #endif  return 0; } 

any solution please.

regards

in c there 3 scopes variables can defined in:

• global scope, when variables defined outside of functions.
• local scope, when variables declared in functions, scope include function arguments.
• block scope, variables defined in blocks nested in functions, example in body of if statement.

variables in 1 scope available in current scope, , nested scopes. don't exist in parallel scopes or scopes of higher level.

more "graphically" seen somethig this:

 +---------------------+ | global scope        | |                     | | +-----------------+ | | | function scope  | | | |                 | | | | +-------------+ | | | | | block scope | | | | | +-------------+ | | | |                 | | | | +-------------+ | | | | | block scope | | | | | +-------------+ | | | +-----------------+ | |                     | | +-----------------+ | | | function scope  | | | |                 | | | | +-------------+ | | | | | block scope | | | | | +-------------+ | | | +-----------------+ | +---------------------+ 

in figure above, there 2 function scopes. variables declared in 1 of function scopes can't used other function scope, local function.

same block scope, variables declared in block can used in block , children of block.

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now how relates problem: variables c , d defined in function abc, means scope in abc function only, other functions (like main function) can't see or access variables defined in abc, variables local in scope of abc function.

there many ways solve problem of accessing these variables other functions, , common beginner way put definition of variables in global scope. in function assign variables, like

array c; array d;  void abc() {     ...     c = array(q, 1, a);     d = array(q, 1, b); } 

other solutions involve passing arguments reference , assigning them. or putting data in structure (class or struct) , returning instance of structure.