I have seen many questions on SO about this particular subject but none of them has any answer for me, so I thought of asking this question. I wanted to generate a random number between [-1, 1]. How I can do this? ...
[Original title referred to 'sizeof function'.] I tried these and they all worked: char *p; printf("Size of *p is %d\n",sizeof(*p)); //result =1 printf("Size of p is %d\n",sizeof( p)); //result =4 printf("Size of p is %d\n",sizeof( //result =4 I wonder why the first printf is 1, the 2nd and 3rd is 4? So what arguments can size...
Given a string of hex values i.e. e.g. "0011223344" so that's 0x00, 0x11 etc. How do I add these values to a char array? Equivalent to say: char array[4] = { 0x00, 0x11 ... }; ...
I have a C++ application that makes a HTTPS connection to one of our servers. In my ideal world, I would like the following to occur: App Starts App makes Windows trust the server's root CA (no GUI please, just system calls) App talks to server, does its work, etc. App makes windows forget about the server's root CA done I do NOT wan...
I want to have an variable-length array contained within a structure, but am having trouble initializing it correctly. struct Grid { int rows; int cols; int grid[]; } int main() { struct Grid testgrid = {1, 3, {4, 5, 6}}; } Everything I try gives me an 'error: non-static initialization of a flexible array member' error. ...
Hi, We have a utility written in C which reads columns extracted from a database using a stored procedure and outputs a csv file. Simple huh. However when reading a smallint column, it crashes out and not being the greatest C programmer on the planet, I can't nail it. As a workaround can you change the data type in a stored procedure e....
I have a C file in which we are moving the logging infrastructure. So if ( logging_level >= LEVEL_FINE ) printf("Value at %p is %d\n", p, i); becomes do_log2(LEVEL_FINE, "Value at %p is %d\n", _ptr(p), _num(i)); do_log2 means log with 2 arguments. So I need a C parsing and modification infrastructure to do this. Which tool can...
Hey Folks, I have a question. I have a legacy application which used bit fields in a structure. Something like this struct sample { BYTE one: 2; BYTE two : 1; BYTE three: 5; } sampletest; So "three" can have a value of MAX 31 only. Now I have a requirement to increase the MAX value of three. I am planning to r...
This post originated from http://stackoverflow.com/questions/1492918/how-do-you-get-what-kind-of-encoding-your-system-uses-in-c-c I tried using nl_langinfo(CODESET) but I got ANSI_X3.4-1968 instead of UTF-8 (which is what I get when typing: locale charmap). Am I using nl_langinfo() wrong? How should I use it? ...
I need to get the memory usage of the current process in C. Can someone offer a code sample of how to do this on a Linux platform? I'm aware of the cat /proc/<your pid>/status method of getting memory usage, but I have no idea how to capture that in C. BTW, it's for a PHP extension I'm modifying (granted, I'm a C newbie). If there are ...
Hi, In my program I read from the serial device (Linux, 8N1) without any problem. But in the case I want to write a single bit, I get nothing out on the interface. I assume that my serial output settings are wrong. But there aren't that many ways how to set c_oflag... My code: #define TTYDEVICE "/dev/ttyS0" #define BAUDRATE B9600 in...
If I have a buffer which contains the data of a file, how can I get a file descriptor from it? This is a question derived from how to untar file in memory ...
So, I have a big piece of legacy software, coded in C. It's for an embedded system, so if something goes wrong, like divide by zero, null pointer dereference, etc, there's not much to do except reboot. I was wondering if I could implement just main() as c++ and wrap it's contents in try/catch. That way, depending on the type of exceptio...
Hi, I was trying to compile the Linux kernel. I am getting the following error:- "No rule to make target arch/x86/kernel/entry_32.o', needed by arch/x86/kernel/built-in.o'." Before this I configured the kernel(didn't do anything extra except the default options). configured the kernel using "make gconfig". The config was generated. I...
Have an array of chars like char members[255]. How can I empty it completely without using a loop? char members[255]; By "empty" I mean that if it had some values stored in it then it should not. For example if I do strcat then old value should not remain members = "old value"; //empty it efficiently strcat(members,"new"); // should...
How is derivative of a f(x) is typically calculated programmatically to ensure maximum accuracy? I am implementing the Newton-Raphson method and it requires taking of the derivative of a function. thanks ...
I have a char* array as follows: char *tbl[] = { "1", "2", "3" }; How do I use the sizeof operator to get the number of elements of the array, here 3? The below did work, but is it correct? int n = sizeof(tbl) / sizeof(tbl[0]) ...
I am implementing an avl tree for my assignment. #include <string.h> #include <stdlib.h> #include <stdio.h> #include <assert.h> struct TreeNode { char *item; struct TreeNode *left; struct TreeNode *right; signed char balance; }; typedef struct TreeNode Node; void _print_avl (Node *, int , const char *); Node * get_new_node (...
Hi, as the questions says, is the C preprocessor able to do it? E.g.: #define PI 3.1416 #define OP PI/100 #define OP2 PI%100 Is there any way OP and/or OP2 get calculated in the preprocessing phase? Thanks. ...
I've been working/coding in C#/Java for some years, so the basics etc. don't give me to much a hard time. But I've never done anything larger than small commandline learning programs in c. Now I'm trying to make a mobile phone emulator for Linux and I have no clue how to structure my code when its not object oriented. I have 3 big books...