I found some interesting code lines:
#include <stdio.h>
int main()
{
printf("Hi there");
return main();
}
It compiles ok (VS2013) and ends up in stackoverflow error because of the recursive call to main(). I didn't know that the return statement accepts any parameter that can be evaluated to the expected return data type, in this example even int main().
Standard C or Microsoft-ish behaviour?
I didn't know that the return statement accepts any parameter that can be evaluated to the expected return data type,
Well, a return statement can have an expression.
Quoting C11 standard, chapter 6.8.6.4, The return statement.
If a
returnstatement with an expression is executed, the value of the expression is returned to the caller as the value of the function call expression.
so, in case of return main();, the main(); function call is the expression.
And regarding the behaviour of return main();, this behaves like a normal recursive function, the exception being an infinite recursion in this case.
Standard
Cor Microsoft-ish behaviour?
As long as C standard is considered, it does not impose any restriction upon calling main() recursively.
However, FWIW, AFAIK, in C++, it is not allowed.
You can redirect the JOIN operation to another macro, which then does the actual pasting, in order to enforce expansion of its arguments: #define VAL1CHK 20 #define NUM 1 #define JOIN1(A, B, C) A##B##C #define JOIN(A, B, C) JOIN1(A, B, C) int x = JOIN(VAL,NUM,CHK); This technique is often used...
As mentioned in the cgo documentation: As Go doesn't have support for C's union type in the general case, C's union types are represented as a Go byte array with the same length. Another SO question: Golang CGo: converting union field to Go type or a go-nuts mailing list post...
If you need bit k (k = 0 ..15), you can do the following: return (lfsr >> k) & 1; This shifts the register kbit positions to the right and masks the least significant bit....
pub_l = malloc(sizeof(pub_l)); is simply not needed. Nor is priv_l = malloc(sizeof(priv_l));. Remove them both from your function. You should be populating your out-parameters; instead you're throwing out the caller's provided addresses to populate and (a) populating your own, then (b) leaking the memory you just allocated. The result is...
javascript,function,getelementbyid,jslint
You missed document prefix. As getElementById is defined on document object you've to call it using document object as follow: document.getElementById("player").play(); // ^^^^^^ Docs...
c,binary-tree,binary-search-tree
a sample to modify like as void inorder ( struct btreenode *, int ** ) ; int* sort(int *array, int arr_size) { struct btreenode *bt = NULL; int i, *p = array; for ( i = 0 ; i < arr_size ; i++ ) insert ( &bt, array[i] ) ;...
string,function,haskell,if-statement,recursion
Your code doesn't handle the case where a line is shorter than the maximum length. This is somewhat obscured by another bug: n is decremented until a whitespace is found, and then f is called recursively passing this decremented value of n, effectively limiting all subsequent lines to the length...
javascript,function,onload,getelementbyid,appendchild
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c,pointers,dynamic-memory-allocation,behavior,realloc
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You have declared coordinate startPt, endPt; in main() and you are trying to access them Readcoordinate(). To resolve error you should declarecoordinate startPt, endPt;inReadcoordinate()` or pass them as argument. coordinate Readcoordinate() { coordinate startPt; cout << "Enter Longitude(in degrees)" << endl; cin >> startPt.latitude >> startPt.longitude >> startPt.city; return startPt;...
int wordCounter(char usStr[]) { int index= sizeof(usStr); int result = 0; for (int i=0; i<index; i++){ if(usStr[index]== ' ') result++; }//end of the loop return result+1; } //try this one. ...
Programs simply do not take integers as arguments, they take strings. Those strings can be decimal representations of integers, but they are still strings. So you are asking how to do something that simply doesn't make any sense. Twenty is an integer. It's the number of things you have if...
c,memory-management,out-of-memory,realloc
When you allocate/deallocate memory many times, it may create fragmentation in the memory and you may not get big contiguous chunk of the memory. When you do a realloc, some extra memory may be needed for a short period of time to move the data. If your algorithm does...
c,arrays,pebble-watch,cloudpebble
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The scanf family of functions are good for simple parsing, but not for more complicated things like you seem to do. You could probably solve it by using e.g. strstr to find the comment starter "//", terminate the string there, and then remove trailing space....
javascript,function,select,options
Something like this? (function (){ var parent = document.getElementById("MediaCategory"); for(var i=0; i< parent.children.length; i++){ var child = parent.children[i]; if(child.text === "Archive") { parent.removeChild(child); } } })(); ...
If you are only looking for fields that match the input, you'll want to search the database using the input string. In other words, write your query string so that it only gives you results that match the user input. This will be much faster than searching through every returned...
There are few fixes required in the code: CallIntMethod should be (*env)->CallIntMethod class Test should be public Invocation should be jint age = (*env)->CallIntMethod(env, mod_obj, mid, NULL); Note that you need class name to call a static function but an object to call a method. (cls2 -> person) mid =...
Are DETUNE1 and DETUNE2 calculated every time it is called? Very unlikely. Because you are calling sqrt with constants, most compilers would optimize the call to the sqrt functions and replace it with a constant value. GCC does that at -O1. So does clang. (See live). In the general...
Important: scanf(" %s", name); has no bounds checking on the input. If someone enters more than 255 characters into your program, it may give undefined behaviour. Now, you have the char array you have the count (number of char in the array), why do you need to bother doing stuffs...
c,visual-studio-2012,linker,static-libraries
C++ uses something called name mangling when it creates symbol names. It's needed because the symbol names must contain the complete function signature. When you use extern "C" the names will not be mangled, and can be used from other programming languages, like C. You clearly make the shunt library...
c,while-loop,char,scanf,getchar
That's because scanf() left the trailing newline in input. I suggest replacing this: ch = getchar(); With: scanf(" %c", &ch); Note the leading space in the format string. It is needed to force scanf() to ignore every whitespace character until a non-whitespace is read. This is generally more robust than...
Well according to this page: http://www.keil.com/support/man/docs/armccref/armccref_BABJFEFG.htm You have __BIG_ENDIAN which is defined when compiling for a big endian target....
The pointer + offset notation is used as a convenient means to reference memory locations. In your case, the pointer is provided by malloc() after allocating sufficient heap memory, and represents an array of M + 2 elements of type char, thus the notation as used in your code represents...
The only difference between the two is the scope of the else. Without the braces, it spans until the end of the full statement, which is the next ;, i.e the next line: else putchar(ch); /* end of else */ lastch = ch; /* outside of if-else */ With the...
javascript,jquery,html,function
You need to put all the calculations into the calc() function: function calc() { // Get Years var years = (document.getElementById('years').value); // Variables var years; var gallons = 1100 * 365; var grain = 45 * 365; var forest = 30 * 365; var co2 = 20 * 365; var...
From printf's manual: The field width An optional decimal digit string (with nonzero first digit) specifying a minimum field width. If the converted value has fewer characters than the field width, it will be padded with spaces on the left (or right, if the left-adjustment flag has been given). Instead...
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javascript,function,methods,overloading
fn.length will return the number of parameters defined in fn. Will arguments.length return the number of which arguments? The already existing function's? No. arguments is an array-like local variable that's available inside of a function. It contains the number of arguments passed to the function. The rest of your...
c,char,segmentation-fault,user-input,scanf
I'm not saying that it cannot be done using scanf(), but IMHO, that's not the best way to do it. Instead, use fgets() to read the whole like, use strtok() to tokenize the input and then, based on the first token value, iterate over the input string as required. A...
function,reporting-services,crystal-reports,ssrs-2008,ssrs-2008-r2
It's a tricky question because grouping in SSRS is handled outside of functions, so the equivalent to condfld is explained here. The short answer is the cell will generally obey the grouping that you have applied to the row. So onto the percent, you'll need an expression (right click on...
Javascript is a client-side language. Session are server-side component. If you want to update session when user does something on your page, you should create a ajax request to the server. Or maybe use some client side variables that, for some aspects, are similar to session (they will be forever...
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In your first code, Case 1: return reverse(i++); will cause stack overflow as the value of unchanged i will be used as the function argument (as the effect of post increment will be sequenced after the function call), and then i will be increased. So, it is basically calling the...
c,arrays,segmentation-fault,initialization,int
In your code, int i is an automatic local variable. If not initialized explicitly, the value held by that variable in indeterministic. So, without explicit initialization, using (reading the value of ) i in any form, like array[i] invokes undefined behaviour, the side-effect being a segmentation fault. Isn't it automatically...
r,function,optimization,mathematical-optimization
I think you want to minimize the square of a-fptotal ... ff <- function(x) myfun(x)^2 > optimize(ff,lower=0,upper=30000) $minimum [1] 28356.39 $objective [1] 1.323489e-23 Or find the root (i.e. where myfun(x)==0): uniroot(myfun,interval=c(0,30000)) $root [1] 28356.39 $f.root [1] 1.482476e-08 $iter [1] 4 $init.it [1] NA $estim.prec [1] 6.103517e-05 ...
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c,algorithm,security,math,encryption
This is not a power operator. It is the XOR operator. The thing that you notice for the XOR operator is that x ^ k ^ k == x. That means that your encryption function is already the decryption function when called with the same key and the ciphertext instead...
You need to use brackets notation to access property by variable: function myFunc( array, fieldToCompare, valueToCompare ) { if( array[fieldToCompare] == "Thiago" ) alert(true); } And wrap name in quotes: myFunc( myArray, 'name', "Thiago" ); ...
What strlen does is basically count all bytes until it hits a zero-byte, the so-called null-terminator, character '\0'. So as long as the string contains a terminator within the bounds of the memory allocated for the string, strlen will correctly return the number of char in the string. Note that...
While you declared the variable averMen, you have not initialized it. The query which should be calculating averMen is calculating averWomen instead. Try changing ... SELECT AVG(DATEDIFF(BIRTH_DATE,CURDATE())) INTO averWomen FROM PLAYERS WHERE sex = 'M'; into SELECT AVG(DATEDIFF(BIRTH_DATE,CURDATE())) INTO averMen FROM PLAYERS WHERE sex = 'M'; ...
This code is broken for two reasons: Accessing a variable twice between sequence points, for other purposes than to determine which value to store, is undefined behavior. There are no sequence points between the evaluation of function parameters. Meaning anything could happen, your program might crash & burn (or more...
Yes, temp_uart_count will contain the actual number of bytes read, and obviously that number will be smaller or equal to the number of elements of temp_uart_data. If you get 0, it means that the end of file (or an equivalent condition) has been reached and there is nothing else to...
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In binary any numbers LSB (Least Significant Bit) is set or 1 means the number is odd, and LSB 0 means the number is even. Lets take a look: Decimal binary 1 001 (odd) 2 010 (even) 3 011 (odd) 4 100 (even) 5 101 (odd) SO, the following line...
java,function,recursion,sum,digit
You aren't actually recursing. You've setup your base case, but when solving a problem recursively you should have code within the function that calls the function itself. So you're missing a line that calls sumDigits, with a smaller argument. Consider two important parts of a recursive soutlion: The base case....
Every time you are creating your string, you are not appending a null terminator, which causes the error. So change this: for(j=0; j<rem_len; j++) { if(j != i) { remaining_for_next[index_4_next] = remaining[j]; index_4_next++; } } to this: for(j=0; j<rem_len; j++) { if(j != i) { remaining_for_next[index_4_next] = remaining[j]; index_4_next++; }...
a,b,c = 1,2,3 while i<n: a,b,c = myfunction(a,b,c) i +=1 ...