.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

<< < … 10 11 12 13 14 15 16 17 > >>   Sort: Date

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, 1506👍, 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, 1506👍, 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, 1505👍, 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, 1505👍, 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, 1500👍, 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, 1499👍, 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, 1498👍, 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, 1496👍, 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, 1496👍, 0💬

Some people say that gotos are evil and that I should never use them. Isnt that a bit extreme
Some people say that gotos are evil and that I should never use them. Isnt that a bit extreme rogramming style, like writing style, is somewhat of an art and cannot be codified by inflexible rules, although discussions about style often seem to center exclusively around such rules. In the case of th... 2015-05-08, 1493👍, 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, 1490👍, 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, 1489👍, 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, 1487👍, 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, 1483👍, 0💬

I am trying to update a file in place ...
I'm trying to update a file in place, by using fopen mode "r+", reading a certain string, and writing back a modified string, but it's not working. Be sure to call fseek before you write, both to seek back to the beginning of the string you're trying to overwrite, and because an fseek or fflush is a... 2015-10-07, 1478👍, 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, 1476👍, 0💬

I am porting this program, and it calls a routine drand48, which my library doesnt have. What is it?
I am porting this program, and it calls a routine drand48, which my library doesnt have. What is it? drand48 is a Unix System V routine which returns floating point random numbers (presumably with 48 bits of precision) in the half-open interval [0, 1). (Its companion seed routine is srand48; neither... 2015-07-20, 1474👍, 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, 1474👍, 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, 1474👍, 0💬

What are the differences between C and CPP?
What are the differences between C and CPP? Q: Is C++ a superset of C? What are the differences between C and C++? Can I use a C++ compiler to compile C code? A: C++ was derived from C, and is largely based on it, but there are some legal C constructs which are not legal C++. Conversely, ANSI C inhe... 2015-01-10, 1473👍, 0💬

Why do some people write if(0 == x) instead of if(x == 0)?
Why do some people write if(0 == x) instead of if(x == 0)? It's a trick to guard against the common error of writing if(x = 0) If you're in the habit of writing the constant before the ==, the compiler will complain if you accidentally type if(0 = x) Evidently it can be easier for some people to rem... 2015-05-15, 1464👍, 0💬

I just typed in this program, and it is acting strangely. Can you see anything wrong with it?
I just typed in this program, and it is acting strangely. Can you see anything wrong with it? See if you can run lint first (perhaps with the -a, -c, -h, -p or other options ). Many C compilers are really only half-compilers, taking the attitude that it's not their problem if you didn't say what you... 2015-05-06, 1464👍, 0💬

How can I find out how much free space is available on disk?
How can I find out how much free space is available on disk? There is no portable way. Under some versions of Unix you can call statfs. Under MS-DOS, use interrupt 0x21 subfunction 0x36, or perhaps a routine such as diskfree. Another possibility is to use popen to invoke and read the output of a ``d... 2015-04-03, 1462👍, 0💬

How can I tell if standard input or output is redirected
How can I tell if standard input or output is redirected (i.e. whether ``&lt;'' or ``&gt;'' was used on the invocation command line)? You can't tell directly, but you can usually look at a few other things to make whatever decision you need to. If you want your program to take input from std... 2015-10-01, 1461👍, 0💬

<< < … 10 11 12 13 14 15 16 17 > >>   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