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How to read the content of a file to a string in C?
... (f)
{
fseek (f, 0, SEEK_END);
length = ftell (f);
fseek (f, 0, SEEK_SET);
buffer = malloc (length);
if (buffer)
{
fread (buffer, 1, length, f);
}
fclose (f);
}
if (buffer)
{
// start to process your data / extract strings here...
}
...
Big O, how do you calculate/approximate it?
...y of an algorithm. It is usually used in conjunction with processing data sets (lists) but can be used elsewhere.
A few examples of how it's used in C code.
Say we have an array of n elements
int array[n];
If we wanted to access the first element of the array this would be O(1) since it does...
How to use glOrtho() in OpenGL?
...nderer only has a certain resolution for depth. If you have your far plane set to 1000 units away and you try draw a tiny model with little faces 0.1 units away from each other, OpenGL wont be able give you the depth resolution you need and you'll get Z-fighting (flickering) between the faces.
...
How exactly does tail recursion work?
...returned) can be optimized if the compiler can make the call in a way that sets up the return address of the called function to be the return address of the function making the tail call, instead of the address from which the tail call was made.
– Steve Jessop
...
Avoid trailing zeroes in printf()
...for the first character in the range 1 to 9 (ASCII value 49-57) then null (set to 0) each char right of it - see below:
void stripTrailingZeros(void) {
//This finds the index of the rightmost ASCII char[1-9] in array
//All elements to the left of this are nulled (=0)
int i = 20;
un...
Are 2^n and n*2^n in the same time complexity?
...an't take the limit of O(f(x)/g(x)); big-O notification is shorthand for a set of functions, not a single function whose value you can limit. However, I think it's true that you can show that f(x) = O(g(x)) if lim(x->infinity) f(x)/g(x) exists.
– chepner
Feb...
What is a Y-combinator? [closed]
...variables and
assignment we can at least avoid having to use
assignment to set up the recursion.
// Here's the function that we want to recurse.
X = function (recurse, n) {
if (0 == n)
return 1;
else
return n * recurse(recurse, n - 1);
};
// This will get X to recurse.
Y = function (bu...
Kill a Process by Looking up the Port being used by it from a .BAT
...le with the below contents, it accepts the input for port number
@ECHO ON
set /p portid=Enter the Port to be killed:
echo %portid%
FOR /F "tokens=5" %%T IN ('netstat -a -n -o ^| findstr %portid% ') DO (
SET /A ProcessId=...
Deleting lines from one file which are in another file
...
Similar to Dennis Williamson's answer (mostly syntactic changes, e.g. setting the file number explicitly instead of the NR == FNR trick):
awk '{if (f==1) { r[$0] } else if (! ($0 in r)) { print $0 } } ' f=1 exclude-these.txt f=2 from-this.txt
Accessing r[$0] creates the entry for that line, n...
How to profile a bash shell script slow startup?
...
PS4='+ $(date "+%s.%N")\011 '
exec 3>&2 2>/tmp/bashstart.$$.log
set -x
add
set +x
exec 2>&3 3>&-
at the end of ~/.bashrc (or at the end of the section of any Bash script you'd like tracing to stop). The \011 is an octal tab character.
You should get a trace log in /tmp...