Win 7 64-bit gcc 4.8.2 (64-bit) cygwin ref: http://stackoverflow.com/questions/23900921/c-scanf-la-returns-0 I don?t know whether you or cygwin supports the gcc runtime library. The reference shows that sscanf works correctly in a Linux environment but not a cygwin environment. The thought is that the fault is in the runtime library. sscanf() doesn't handle "%la" correctly and crashes on "%a". Sample code and output: # include <stdio.h> # include <iostream> #include <cstdlib> using namespace std; int main(int argc, char** argv) { char buffer[30]; double x = 5.0; sprintf(buffer, "%a", 1.2); sscanf(buffer, "%la", &x); cout << " Example 1.2 buffer -> " << buffer << endl; cout << " Example 1.2 scanf <- " << x << endl; return 0; } output Example 1.2 buffer -> 0x1.3333333333333p+0 Example 1.2 scanf <- 0
