Convert string with thousands (and decimal) separator into double

Question

User can enter double into textbox. Number might contain thousands separators. I want to validate user input, before inserting entered number into database.

Answer 1

A C solution would be to use setlocale & sscanf:

const char *oldL = setlocale(LC_NUMERIC, "de_DE.UTF-8");
double d1 = 1000.43, d2 = 0;
sscanf("1.000,43", "%'lf", &d2);
if ( std::abs(d1-d2) < 0.01 )
  printf("OK \n");
else
  printf("something is wrong! \n");
setlocale(LC_NUMERIC, oldL);