.NET C C++ CSS DBA General HTML Java JavaScript JSP JUnit MySQL Networking Oracle Perl Perl PHP PL/SQL RSS Software QA SQL Server Struts Unix Windows XHTML XML

<< < … 4 5 6 7 8 9 10 11 12 13 14 … > >>   Sort: Date

Does C have an equivalent to Pascals with statement?
Does C have an equivalent to Pascals with statement? No. The way in C to get quick and easy access to the fields of a structure is to declare a little local structure pointer variable (which, it must be admitted, is not quite as notationally convenient as a with statement and doesn't save quite as m... 2015-01-14, 1592👍, 0💬

Why cant I open a file by its explicit path?
Why can't I open a file by its explicit path? The call fopen("c:\newdir\file.dat", "r") is failing. The file you actually requested--with the characters \n and \f in its name--probably doesn't exist, and isn't what you thought you were trying to open. In character constants and string literals, the ... 2015-04-08, 1590👍, 0💬

What is assert and when would I use it?
What is assert and when would I use it? It is a macro, defined in &lt;assert.h>, for testing ``assertions''. An assertion essentially documents an assumption being made by the programmer, an assumption which, if violated, would indicate a serious programming error. For example, a function which ... 2015-01-12, 1588👍, 0💬

Why does the simple line-copying loop while ...
Why does the simple line-copying loop while(!feof(infp)) { fgets(buf, MAXLINE, infp); fputs(buf, outfp); } copy the last line twice? p> In C, end-of-file is only indicated after an input routine has tried to read, and failed. (In other words, C's I/O is not like Pascal's.) Usually, you should just c... 2015-11-13, 1587👍, 0💬

Should I use symbolic names like TRUE and FALSE for Boolean constants, or plain 1 and 0?
Should I use symbolic names like TRUE and FALSE for Boolean constants, or plain 1 and 0? It's your choice. Preprocessor macros like TRUE and FALSE (and, of course, NULL) are used for code readability, not because the underlying values might ever change. It's a matter of style, not correctness, wheth... 2016-02-29, 1584👍, 0💬

I am getting strange syntax errors inside lines I have ifdeffed out.
I am getting strange syntax errors inside lines I have ifdeffed out. Under ANSI C, the text inside a ``turned off'' #if, #ifdef, or #ifndef must still consist of ``valid preprocessing tokens.'' This means that the characters " and ' must each be paired just as in real C code, and the pairs mustn't c... 2015-12-14, 1584👍, 0💬

My ANSI compiler complains about a mismatch when it see
My ANSI compiler complains about a mismatch when it sees extern int func(float); int func(x) float x; { ... You have mixed the new-style prototype declaration ``extern int func(float);'' with the old-style definition ``int func(x) float x;''. It is usually possible to mix the two styles but not in t... 2016-01-13, 1583👍, 0💬

Why doesn't sizeof tell me the size of the block of memory pointed to by a pointer?
Why doesn't sizeof tell me the size of the block of memory pointed to by a pointer? sizeof tells you the size of the pointer. There is no portable way to find out the size of a malloc'ed block. (Remember, too, that sizeof operates at compile time 2016-03-21, 1582👍, 0💬

What if a built-in logical or relational operator `returns something other than 1? ....
Isn't #defining TRUE to be 1 dangerous, since any nonzero value is considered ``true'' in C? What if a built-in logical or relational operator ``returns'' something other than 1? It is true (sic) that any nonzero value is considered true in C, but this applies only ``on input'', i.e. where a Boolean... 2016-02-29, 1582👍, 0💬

Suggesting that there can be 62 seconds in a minute?
Suggesting that there can be 62 seconds in a minute? Q: Why can tm_sec in the tm structure range from 0 to 61, suggesting that there can be 62 seconds in a minute? A: That's actually a buglet in the Standard. There can be 61 seconds in a minute during a leap second. It's possible for there to be two... 2015-01-05, 1582👍, 0💬

fopen isnt letting me open files like "$HOME/.profile" and "~/.myrcfile".
fopen isn't letting me open files like "$HOME/.profile" and "~/.myrcfile". Under Unix, at least, environment variables like $HOME, along with the home-directory notation involving the ~ character, are expanded by the shell, and there's no mechanism to perform these expansions automatically when you ... 2015-04-06, 1580👍, 0💬

I am starting to think about multinational character sets ....
I'm starting to think about multinational character sets, and I'm worried about the implications of making sizeof(char) be 2 so that 16-bit character sets can be represented. If type char were made 16 bits, sizeof(char) would still be 1, and CHAR_BIT in &lt;limits.h> would be 16, and it would si... 2016-03-02, 1578👍, 0💬

What is hashing?
What is hashing? Hashing is the process of mapping strings to integers, usually in a relatively small range. A ``hash function'' maps a string (or some other data structure) to a bounded number (the ``hash bucket'') which can more easily be used as an index in an array, or for performing repeated co... 2015-01-07, 1577👍, 0💬

My programs prompts and intermediate output dont always show up on the screen ...
My program's prompts and intermediate output don't always show up on the screen, especially when I pipe the output through another program. It's best to use an explicit fflush(stdout) whenever output should definitely be visible (and especially if the text does not end with \n). Several mechanisms a... 2015-11-11, 1575👍, 0💬

Is there a way to switch on strings?
Is there a way to switch on strings? Not directly. Sometimes, it's appropriate to use a separate function to map strings to integer codes, and then switch on those: #define CODE_APPLE 1 #define CODE_ORANGE 2 #define CODE_NONE 0 switch(classifyfunc(string)) { case CODE_APPLE: ... case CODE_ORANGE: ..... 2015-02-04, 1575👍, 0💬

Is it acceptable for one header file to #include another?
Is it acceptable for one header file to #include another? It's a question of style, and thus receives considerable debate. Many people believe that ``nested #include files'' are to be avoided: the prestigious Indian Hill Style Guide disparages them; they can make it harder to find relevant definitio... 2016-02-16, 1570👍, 0💬

Why does everyone say not to use scanf? What should I use instead?
Why does everyone say not to use scanf? What should I use instead? scanf has a number of problems, its %s format has the same problem that gets() has --it's hard to guarantee that the receiving buffer won't overflow. More generally, scanf is designed for relatively structured, formatted input (its n... 2015-10-21, 1570👍, 0💬

I am splitting up a program into multiple source files for the first time ...
I'm splitting up a program into multiple source files for the first time, and I'm wondering what to put in .c files and what to put in .h files. (What does ``.h'' mean, anyway?) As a general rule, you should put these things in header (.h) files: macro definitions (preprocessor #defines) structure, ... 2016-02-18, 1569👍, 0💬

I am appalled that the ANSI Standard leaves so many issues undefined ...
I'm appalled that the ANSI Standard leaves so many issues undefined. Isn't a Standard's whole job to standardize these things? It has always been a characteristic of C that certain constructs behaved in whatever way a particular compiler or a particular piece of hardware chose to implement them. Thi... 2015-11-18, 1568👍, 0💬

Are the outer parentheses in return statements really optional?
Are the outer parentheses in return statements really optional? Yes. Long ago, in the early days of C, they were required, and just enough people learned C then, and wrote code which is still in circulation, that the notion that they might still be required is widespread. (As it happens, parentheses... 2015-02-02, 1567👍, 0💬

Does C have circular shift operators?
Does C have circular shift operators? No. (Part of the reason why is that the sizes of C's types aren't precisely defined----but a circular shift makes most sense when applied to a word of a particular known size.) You can implement a circular shift using two regular shifts and a bitwise OR: (x &... 2015-01-28, 1567👍, 0💬

People keep saying that the behavior of ...
People keep saying that the behavior of i = i++ is undefined, but I just tried it on an ANSI-conforming compiler, and got the results I expected. A compiler may do anything it likes when faced with undefined behavior (and, within limits, with implementation-defined and unspecified behavior), includi... 2015-11-18, 1566👍, 0💬

How can I find out how much memory is available?
How can I find out how much memory is available? Your operating system may provide a routine which returns this information, but it's quite system-dependent. (Also, the number may vary over time.) If you're trying to predict whether you'll be able to allocate a certain amount of memory, just try it-... 2015-03-30, 1566👍, 0💬

How can I write a function which takes a variable number of arguments
How can I write a function which takes a variable number of arguments and passes them to some other function (which takes a variable number of arguments)? In general, you cannot. Ideally, you should provide a version of that other function which accepts a va_list pointer. Suppose you want to write a... 2015-06-05, 1565👍, 0💬

<< < … 4 5 6 7 8 9 10 11 12 13 14 … > >>   Sort: Date

.NET C C++ CSS DBA General HTML Java JavaScript JSP JUnit MySQL Networking Oracle Perl Perl PHP PL/SQL RSS Software QA SQL Server Struts Unix Windows XHTML XML