.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

<< < … 167 168 169 170 171 172 173 174 > >>   Sort: Date

How can I get the current date or time of day in a C program?
How can I get the current date or time of day in a C program? Just use the time, ctime, localtime and/or strftime functions. Here is a simple example: #include &lt;stdio.h> #include &lt;time.h> int main() { time_t now; time(&amp;now); printf("It's %s", ctime(&amp;now)); return 0; } C... 2015-08-07, 1471👍, 0💬

Why do all the lines end up containing copies of the last line?
I'm using fgets to read lines from a file into an array of pointers. Why do all the lines end up containing copies of the last line? You have only allocated memory for one line, linebuf. Each time you call fgets, the previous line is overwritten. fgets doesn't do any memory allocation: unless it rea... 2015-11-13, 1469👍, 0💬

How can I find the modification date and time of a file?
How can I find the modification date and time of a file? The Unix and POSIX function is stat, which several other systems supply as well. 2015-04-13, 1467👍, 0💬

How can my program discover the complete pathname to the executable from which it was invoked?
How can my program discover the complete pathname to the executable from which it was invoked? argv[0] may contain all or part of the pathname, or it may contain nothing. You may be able to duplicate the command language interpreter's search path logic to locate the executable if the name in argv[0]... 2015-03-13, 1465👍, 0💬

But I cant use all these nonstandard, system-dependent functions, because my program has to be ANSI compatible!
But I cant use all these nonstandard, system-dependent functions, because my program has to be ANSI compatible! You're out of luck. Either you misunderstood your requirement, or it's an impossible one to meet. ANSI/ISO Standard C simply does not define ways of doing these things; it is a language st... 2015-02-27, 1465👍, 0💬

How can I return a sequence of random numbers which dont repeat at all?
How can I return a sequence of random numbers which dont repeat at all? What you're looking for is often called a ``random permutation'' or ``shuffle.'' One way is to initialize an array with the values to be shuffled, then randomly interchange each of the cells with another one later in the array: ... 2015-07-24, 1464👍, 0💬

How can I insert or delete a line (or record) in the middle of a file?
How can I insert or delete a line (or record) in the middle of a file? In general, there is no way to do this. The usual solution is simply to rewrite the file. When you find yourself needing to insert data into an existing file, here are a few alternatives you can try: * Rearrange the data file so ... 2015-10-05, 1463👍, 0💬

A third-party header file I just started using is defining its own TRUE and FALSE values incompatibly ...
A third-party header file I just started using is defining its own TRUE and FALSE values incompatibly with the code I've already developed. What can I do? This is indeed an annoying situation. It's a classic namespace problem;Ideally, third-party vendors would be conscientious when defining symbols ... 2016-02-26, 1462👍, 0💬

I am reading a number with scanf and d, and then a string with gets
I'm reading a number with scanf and %d, and then a string with gets(): int n; char str[80]; printf("enter a number: "); scanf("%d", &amp;n); printf("enter a string: "); gets(str); printf("you typed %d and "%s"\n", n, str); but the compiler seems to be skipping the call to gets()! If, in response... 2015-10-23, 1461👍, 0💬

How can I send mail from within a C program?
How can I send mail from within a C program? Under Unix, open a pipe to the mail program, or perhaps /usr/lib/sendmail. 2015-04-17, 1461👍, 0💬

How can I write code to conform to these old, binary data file formats?
How can I write code to conform to these old, binary data file formats? It's hard, because of word size and byte order differences, floating-point formats, and structure padding. To get the control you need over these particulars, you may have to read and write things a byte at a time, shuffling and... 2015-09-18, 1460👍, 0💬

How can I flush pending input so that a user ...
How can I flush pending input so that a user's typeahead isn't read at the next prompt? Will fflush(stdin) work? fflush is defined only for output streams. Since its definition of ``flush'' is to complete the writing of buffered characters (not to discard them), discarding unread input would not be ... 2015-10-12, 1459👍, 0💬

I have a program that seems to run correctly
I have a program that seems to run correctly, but it crashes as it's exiting, after the last statement in main(). What could be causing this? A:There are at least three things to look for: 1. If a semicolon in a previous declaration is missing, main might be inadvertently declared as returning a str... 2015-05-29, 1457👍, 0💬

I keep getting errors due to library functions being undefined, but I am including all the right header files.
I keep getting errors due to library functions being undefined, but I am including all the right header files. In the general case of calling code in an external library, using #include to pull in the right header file(s) is only half of the story; you also have to tell the linker to search the exte... 2015-07-14, 1455👍, 0💬

How can I do graphics?
How can I do graphics? Once upon a time, Unix had a fairly nice little set of device-independent plot functions described in plot(3) and plot(5). The GNU libplot library, written by Robert Maier, maintains the same spirit and supports many modern plot devices; see http://www.gnu.org/software/pl otuti... 2015-04-17, 1454👍, 0💬

I heard that you have to include stdio.h before calling printf. Why?
I heard that you have to include stdio.h before calling printf. Why? So that a proper prototype for printf will be in scope. A compiler may use a different calling sequence for functions which accept variable-length argument lists. (It might do so if calls using variable-length argument lists were l... 2015-06-17, 1452👍, 0💬

Did C have any Year 2000 problems?
Did C have any Year 2000 problems? No, although poorly-written C programs might have. The tm_year field of struct tm holds the value of the year minus 1900; this field therefore contains the value 100 for the year 2000. Code that uses tm_year correctly (by adding or subtracting 1900 when converting ... 2015-08-03, 1445👍, 0💬

How can I write a function that takes a variable number of arguments?
How can I write a function that takes a variable number of arguments? Use the facilities of the &lt;stdarg.h> header. Here is a function which concatenates an arbitrary number of strings into malloc'ed memory: #include &lt;stdlib.h> /* for malloc, NULL, size_t */ #include &lt;stdarg.h> /... 2015-06-15, 1445👍, 0💬

Is exit(status) truly equivalent to returning the same status from main?
Is exit(status) truly equivalent to returning the same status from main? Yes and no. The Standard says that a return from the initial call to main is equivalent to calling exit. However, a return from main cannot be expected to work if data local to main might be needed during cleanup; A few very ol... 2015-07-20, 1442👍, 0💬

How can I read data from data files with particular formats?
How can I read data from data files with particular formats? How can I read ten floats without having to use a jawbreaker scanf format like "%f %f %f %f %f %f %f %f %f %f"? How can I read an arbitrary number of fields from a line into an array? In general, there are three main ways of parsing data l... 2015-10-26, 1440👍, 0💬

Dont ANSI function prototypes render lint obsolete?
Dont ANSI function prototypes render lint obsolete? Not really. First of all, prototypes work only if they are present and correct; an inadvertently incorrect prototype is worse than useless. Secondly, lint checks consistency across multiple source files, and checks data declarations as well as func... 2015-05-01, 1440👍, 0💬

How can I check whether a file exists? I want to warn the user if a requested input file is missing.
How can I check whether a file exists? I want to warn the user if a requested input file is missing. It's surprisingly difficult to make this determination reliably and portably. Any test you make can be invalidated if the file is created or deleted (i.e. by some other process) between the time you ... 2015-04-15, 1433👍, 0💬

How can I find out the size of a file, prior to reading it in?
How can I find out the size of a file, prior to reading it in? If the ``size of a file'' is the number of characters you'll be able to read from it in C (or which were written to it by a previous program), it can be difficult or impossible to determine this number exactly (other than by reading the ... 2015-04-15, 1432👍, 0💬

How can I shut off the warning ...
How can I shut off the ``warning: possible pointer alignment problem'' message which lint gives me for each call to malloc? A modern lint shouldn't be complaining about this. Once upon a time, lint did not and could not know that malloc ``returns a pointer to space suitably aligned for storage of an... 2015-05-05, 1430👍, 0💬

<< < … 167 168 169 170 171 172 173 174 > >>   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