Hi, I posted this message on gcc/bug forum earlier. I repost the same contents here. I need experts to shed light on C/C++ data type size inconsistencies when running 64-bit and 32-bit ELF executables compiled by GNU/GCC g++/gcc Following are results of C/C++ data type size from code " cout << "data type" << sizeof(data type) << endl " : | 32-bit | 64-bit ------------------------------- int | 4 | 4 ------------------------------- long int | 4 | 8 ------------------------------- signed long int | 4 | 4 ------------------------------- ulong | 4 | 8 (sys/types.h) ------------------------------- long double | 12 | 16 Thank in advance, Tom -- View this message in context: http://www.nabble.com/Size-of-C-C%2B%2B-data-type-from-GNU-GCC-g%2B%2B-compiled-ELF-64-bit-LSB-executable%2C-AMD-x86-64-vs.-ELF-32-bit-LSB-executable%2C-Intel-80386-tf3942845.html#a11184115 Sent from the gcc - Help mailing list archive at Nabble.com.