C - Check if a value is a number?
How can I check if an integer initialized from function scanf is a number? ...in the simpler way possible thanks :) ...
c
Macro undeclared, but defined in header
I'm facing a very weird problem. This is map.h: #define MAP_WIDTH 256 #define MAP_HEIGHT 256 typedef struct { char exit_n; char exit_s; char exit_w; char exit_e; } room; room map[MAP_WIDTH][MAP_HEIGHT]; void generate_map(); And this map.c: #include "map.h" void generate_map() { char room_x, room_y; ro...
Append Formatted String to String in C (not C++) Without Pointer Arithmetic?
Hi all, Wrote a very simple C function to illustrate what I would like to simplify: void main(int argc, char *argv[]){ char *me="Foo"; char *you="Bar"; char us[100]; memset(us,100,0x00); sprintf(us,"You: %s\n",you); sprintf(us+strlen(us),"Me: %s\n",me); sprintf(us+strlen(us),"We are %s and %s!\n",me,you); ...
Modify detab to accept list of tab stops
This is my version of detab, from this K&R exercise: Modify detab to accept a list of tab stops as arguments. Use the default tab setting if there are no arguments. #include <stdio.h> #include <stdlib.h> #define TAB_STOP 8 /* replaces tabs from input with the proper amount of blank spots */ int Detab() { int c, x; int co...
C: Dynamic array of pointers to array of structure
Hi, I have a structure and a bidimensional array of those structs: typedef struct { char exit_n; char exit_s; char exit_w; char exit_e; } room; room map[MAP_WIDTH][MAP_HEIGHT]; I need an array of pointers those structs. The following code compiles, but I don't get the wanted result. Any help? This is getting really confused to me, a...
how to modify detab to accept list of arguments
#include <stdio.h> #include <stdlib.h> #include <ctype.h> #define TAB_STOP 8 /* replaces tabs from input with the proper amount of blank spots */ int Detab() { int c, x; int column; x = column = 0; while((c=getchar())!=EOF) { if(c == '\n') /* reseting counter if newline */ { putchar(...
Convert a string to int (But only if really is an int)
In college I was asked if our program detects if the string enter from command line arguments is a integer which it did not(./Program 3.7). Now I am wondering how I can detect this. So input as for example a is invalid which atoi detects, but input like for example 3.6 should be invalid but atoi will convert this to an integer. #includ...
Parsing a bit field parameter, how to "discard" bits in an unsigned long?
Hey all, First of all, I want to know if this is possible: let's say I have an unsigned long which contains some abritrary unsigned shorts, which may or may not be in the number. For example: unsigned short int id1 = 3456, id2 = 30998; unsigned long long bitfld = id1|id2; Can the other 2 fields be assumed as 0? An...
asynchronous programming
Hello gcc 4.4.1 I am writing a server program where many clients will connect to the client and the server will manage the clients request and manage the state of the client. Many clients under high load would be a deciding factor in using Asynchronous programming. However, I have never done Async in C. However, from what I understand...
C Macro Question -(x) vs (-x)
I'm going through quiz answers from my professor and a question was: the correct implementation of a function like macro for absolute value is: #define abs(x) ((x)<0 ? (-x) : (x)) #define abs(x) ((x)<0 ? -(x) : (x)) Why is the second one correct vs the first one? And why do you have to use all the (). Like what are the rules invol...
Line Drawing Algorithm
I wrote a line drawing algorithm using the wu technique. It works but has issues. See below. What I'm wondering is if anyone has tackled the problem of drawing anti-aliased lines? Suprisingly, a google search results in no satisfactory algorithms. Lots of discusions, but not a single complete, robust algorithm, independent of any dep...
How to become a great open source programmer of python?
Hi, I'm a C# programmer of web applications. Weeks ago, I asked a question on stackoverflow about What should a software engineer (web) start by learning - Erlang, Haskell, Python, C++, F#. Thanks to all of those who suggested their thoughts and help to make a decision. I've found Python should be the one I should start looking forward...
What does ## mean for the C(C++) preprocessor ?
i have a c program below: #define f(g,g2) g##g2 main() { int var12=100; printf("%d",f(var,12)); } when i run just the preprocessor it expands this as { int var12=100; printf("%d",var12); } which is the reason why the output is 100. can anybody tell me how/why the preprocessor expands var##12 to var12? ...
How do I convert (latitude,longitude) into (x,y) coordinates?
What is the formula for real world (latitude,longitude) conversion into (x,y) coordinates? ...
Xilinx Microblaze C and assembly
I have an application written in C for a Xilinx Microblaze core. However, the performance isn't quite what I want so I was considering rewriting some of the core functions in assembly. I'm having trouble figuring out how to get Xilinx Platform Studio to compile both into a single ELF file though. How can I do it? ...
Want to avoid one call to sempost for eight threads
Scenario is: nthreads = 8 for j=0 = nthreads pthread_created (thread_func) for 1=0 to 1000 { // Some work. for j=0 = nthreads sempost(mutex1) // thread_func() for j=0 = nthreads semwait(mutex2) // Some work. } thread_func() { w...
Difference in linkage between C and C++?
I have read the existing questions on external/internal linkage over here on SO. My question is different - what happens if I have multiple definitions of the same variable with external linkage in different translation units under C and C++? For example: /*file1.c*/ typedef struct foo { int a; int b; int c; } foo; foo xy...
C Winsock programming: input garbage
Hi to all, I'm programming a very simple socket server following this sample code. The server is up and running and I can connect to it via telnet (using Putty, actually). Whenever a new connection is received, I spawn a new thread that is the following code: DWORD WINAPI receive_cmds(LPVOID lpParam) { char outbuffer[100]; ...
Horizontal scroll bar appears even for 1 or 2 char length
I am using a table layout panel with autoscroll = true I found several issues which don't seem to work properly. One of them is that when I have more rows then in view and the vertical scroll bar is added along with the horizontal scroll bar. Actually this horizontal scroll bar should not appear until unless it exceeds the width of th...
What's a good introductory book on Data Structures
Possible Duplicate: What is a good book to study data structures in C? Please recommend a good beginner-intermediate book on data structures. Preferably a printed book, with code in C (or language-agnostic). ...