qudarap/tests/populate_array_test.cc

0001 // name=populate_array_test ; gcc $name.cc -std=c++11 -lstdc++ -o /tmp/$name && /tmp/$name
0002
0003 #include <iostream>
0004 #include <sstream>
0005 #include <string>
0006
0007 const int N = 16 ;
0008
0009 template<typename T>
0010 std::string desc( const T* tt, int num )
0011 {
0012     std::stringstream ss ;
0013     for(int i=0 ; i < num ; i++ ) ss << tt[i] << " " ;
0014     ss << std::endl ;
0015     std::string str = ss.str();
0016     return str ;
0017 }
0018
0019 /**
0020 populate_array_0
0021 ------------------
0022
0023 pointer-to-pointer argument enables the function
0024 to populate a structure from the calling scope
0025
0026 **/
0027
0028 template<typename T>
0029 void populate_array_0( T** arr, int num )
0030 {
0031     for(int i=0 ; i < num ; i++) (*arr)[i] = T(i) ;
0032 }
0033 void test_0()
0034 {
0035     float ss[N] ;
0036     float* ss_ptr = ss ;
0037     populate_array_0( &ss_ptr, N );
0038
0039     std::cout << "test_0: " << desc(ss, N) ;
0040 }
0041
0042 /**
0043 populate_array_1
0044 -------------------
0045
0046 BUT : no need for pointer-to-pointer
0047 because there us no need to change the location
0048 of that structure. Just need to fill it, so
0049 one level of indirection is fine.
0050
0051 **/
0052
0053 template<typename T>
0054 void populate_array_1( T* arr, int num )
0055 {
0056     for(int i=0 ; i < num ; i++) arr[i] = T(i) ;
0057 }
0058 void test_1()
0059 {
0060     float ss[N] ;
0061     populate_array_1( ss, N );
0062     std::cout << "test_1: " << desc(ss, N) ;
0063 }
0064
0065
0066 int main(int argc, char** argv)
0067 {
0068     test_0();
0069     test_1();
0070     return 0 ;
0071 }