64-Bit Types in Java Encoder pdf417 in Java 64-Bit Types

64-Bit Types using barcode writer for j2se control to generate, create pdf417 image in j2se applications. Code 93 The off_t ty PDF-417 2d barcode for Java pe, for example, is used in the POSIX APIs such as lseek and mmap. It can be either a 32-bit size or a 64-bit size, depending on compiler flags. By default, you get a 32-bit type, but GNU allows you to replace off_t with a 64-bit type by compiling with the flag.

-D_FILE_OFFSET_BITS=64 When a 64-bi jvm pdf417 2d barcode t type appears as an argument to an integer or long integer format, the output will not be correct. Worse, because the size is different, subsequent arguments will also be incorrect or could even cause your application to crash. The warning in this case differs in different versions of gcc:.

gcc 3.x: war ning: int format, different type arg gcc 4.x: warning: format "%x" expects type "unsigned int", but argument 2 has type "off_t".

10 Debugging This warning is relevant whether you are compiling on 64-bit or 32-bit architectures. The type long long has been used by gcc and other compilers to represent 64-bit types on 32-bit architectures. The format for a long long type is ll, for example:.

printf("%lld\n", x);. The situatio n is a bit messy. On x86_64 architectures, gcc recognizes both long and long long as 64-bit types. And wouldn t you know, printf requires the format to match the type, even though the types are the same size.

On IA32, for example, gcc implements C99 s int64_t type as a long long, but on x86_64, gcc uses type long. So to build on IA32 without warnings, a printf format requires "%lld", whereas the same code compiled on x86_64 requires "%ld"..

Floating-Point Types Mixing float ing-point and integer types is just as dangerous as mixing 64-bit and 32-bit types. That s because the double type is 64 bits. Interestingly though, mixing float with double arguments is not a problem, because C promotes a float to a double when it appears in a variable argument list.

For the same reason, using a float argument to an integer format can be catastrophic, because the float is promoted to double, and integer arguments are all 32-bits. Again the warning is slightly different in different versions of gcc:. gcc 3.x: war swing barcode pdf417 ning: int format, double arg (arg 2) gcc 4.x: warning: format "%d" expects type "int", but argument 2 has type "double".

Note that in both cases, the actual argument was float, but the compiler warning takes into account the fact that the compiler promotes it to double.. String Types String types are perhaps the most likely sources of error, because they take pointers as arguments, and pointers can go wrong in so many ways. Again, the warning varies from one release to the next of gcc:. gcc gcc gcc pdf417 2d barcode for Java gcc 3.x: 3.x: 4.

x: 4.x: warning: warning: warning: warning: format argument is not a pointer (arg 2) char format, different type arg (arg 2) format "%s" expects type "char *", but argument 2 has type "int" format "%s" expects type "char *", but argument 2 has type "int *". The code res ponsible for these warnings is likely to produce crashes at runtime. If you see one of these warnings, you should inspect the code and fix it. If the code is correct as is, use an explicit type cast to remove the warning.

. The Most Basic Debugging Tool: printf 10.2.2.

4 Tip s for Creating Good Debug Messages A formatting convention can give you indication at a glance of what is going on without requiring you to read every line of printout.. Use an Easily Recognizable Format Adults read by recognizing the shapes of words, not by sounding out every letter in a word. A consistent format will take advantage of this fact by giving good messages one shape and bad messages another. Consider this rubbish, which could have come from your favorite program:.

debug> Th PDF417 for Java e LAST time I cHecked, the DVD drive is within tolerances. Relax, THE hard drive is runniNg. -- The USB port is not In flames.

It"s a good thing that the pcI bus is running. I"m optimistic because the usb port is better. Don"t paNic, but the DVd Drive is going tO explode.

The last time I checKed, THE heap is OptImal. debug> The moUse IS not in flames. running at full speed.

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