Is this the correct approach to do input validation with floating point values?

Question

After spending a good amount of time researching input validation, I combined a few ideas and came up with this:

Function to check a string for a valid dou

Answer 1

Perhaps the strtod() function can be of help here, as it tells you how much has been converted:

const char * buf = get_raw_data(); // somehow

char * endptr;
const double value = strtod(buf, &endptr);

if (endptr != buf + std::strlen(buf))  { /* ... error ... */ }

As the source for buf you could tokenize your input with std::string token; std::cin >> token; or something like that and use token.c_str().