C++ :: Validate Unsigned Operations?
Oct 12, 2012
I've sometimes encountered unexpected runtime issues caused by unsigned values being decremented below zero.
Example 1: "unsigned_value += negative_integer_value;"
Example 2: "for( size_t i = size - 1; i >= 0; --i )"
My compiler doesn't provide any compile-time or run-time warnings.
As far as I know, it's not possible to overload operators of primitive data types to check if the unsigned value is decremented below zero.
Any clever strategy to trace such cases at debug runtime, without having to add asserts all over the code? It's important that it does not affect performance in release mode.
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Apr 3, 2014
How can i write a function that will read an "unsigned integer" into a variable of type "unsigned short int"? i can not use cin >> inside the function.. so i am looking for atleast a hint!
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Oct 5, 2012
I am new to C++ and I want to validate the xml based on the XML Schema in C++. Some tools/libraries to achieve that.
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Jul 14, 2013
How would I validate the date?
struct Inventory {
char SKU[SKU_SIZE];
char category[CAT_SIZE];
int qty;
double cost;
char date[CAT_SIZE];
[Code] .....
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Oct 24, 2013
For the following program, I'd like to make sure the user input is between 1 and 40 characters. To do this, how would I complete the if statement below?
Code:
char p_input[41];
printf("Enter a name (1-40 characters):");
fgets(p_input, 41, stdin);
if (p_input ....??
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Jul 2, 2013
Im having trouble with the while loop, this program should ask the user for their name, if incorrect it should send an error msg and ask for input again...after the correct name is entered the program should prompt the user to enter a password, again if incorrect it should send an error msg and ask for input again.
the code below does what it should when asking for a name..HOWEVER it does not allow the user to enter a password and instead jumps straight to the error msg..
#include<iostream>
#include<string>
#include<iomanip>
using namespace std;
int main() {
// Variables
string username;
string password;
[Code] .....
After the correct name is entered, the program displays this:
"Welcome, Sadia Rajput."
"To continue, enter your password: That is incorrect, enter password: "
I would prefer to do this using the while loops and not bool statements
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Jun 21, 2014
I am trying to build a employee management system using C, and I have done alot so far. Everything seems to work fine, but then I thought that I should let the user store the data of their employees permanently, therefore I created a file and then I store the user's given data in the txt file.
Here is the code:
#include<stdio.h>
#include<conio.h>
#include<string.h>
[Code].....
But there is some problem, and I don't seem to understand what is the problem in the code, it's just that whenever the user enters any id to search, and presses any key then nothing appears just a blank screen! I wanted to know that how can I check the ID from the text file and then display the details of the employee of that id!
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Apr 30, 2012
How to validate if the item you want to add in the cart is already exists in listView items? for example I already add CH001 which is the productId of Chocolate strawberry, then I accidentally add again that product Id and I what I want is that it should not be accepted on my listview again because CH001 is already on my cart.
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Aug 5, 2014
I'm having a problem with the two while statements in my UDF.
- 1. It will run both while loops twice...?
- 2. It now goes into a continuous loop.
- 3. When it did work, it would only return 1 value to the main()...?
#include <iostream> // for use of "cin" & "cout", endl...
#include <iomanip> // for formatting setw function
#include <cmath> // for the general math computations
#include <string> // for creating descriptive strings
#include <sstream> // used to convert a string to an integer
//user defined function
int userValue (int);
[code].....
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Sep 24, 2014
How to validate the data if the data already exist in the table record in c#?
For example I wanted to add the student roll no. if roll no. is 134 and if we are adding rollno. 134 student then we get the warning like roll no. 134 is already exist ....
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Mar 30, 2014
unsigned char key[32];
139 unsigned char rfseed[32];
173 f = fopen("/dev/urandom","rb");
174 fread(key,1,32,f);
175 fread(rfseed,1,32,f);
I am having problems copying outputs of the above code into other unsigned char other[32]. I need to keep the output of dev/urandom for backup. But, when I try to assign the values by memcpy(other, key, 32), the values do not match. The same problem happens by assigning values index by index in a loop.
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Mar 12, 2014
I'm used to writing enums for enumerated types. However I have this:
enum Colour
{
BLUE = 0x01,
BLACK = 0x02,
WHITE = 0x04,
GREEN = 0x08,
RED = 0x10
};
Now each of the enumerated types are not exclusive, so I'd like to do this:
Colour c = BLUE | BLACK;
Of course that doesn't work. gcc gives "invalid conversion from 'int' to 'Colour' [-fpermissive]".
typedef int Colour;
static const Colour BLUE = 0x01;
static const Colour BLACK = 0x02;
static const Colour WHITE = 0x04;
static const Colour GREEN = 0x08;
static const Colour RED = 0x10;
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Feb 4, 2014
So I think I am having syntactical problem with my code.
Code:
int main() {
vector<int> ivec;
int score;
[Code] ....
I get an error from my compiler on the ?10th? line (Nested condition line) that says |19|error: invalid operands of types 'int' and '<unresolved overloaded function type>' to binary 'operator<<'|
The purpose of the program is to take input and store it in a vector and then change the value to be between 1-6. I made this for the purpose of learning about nested conditional operations.
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Mar 16, 2014
Code:
#include<stdio.h>
#include<conio.h>
void main()
{
float i;
i=0.7;
[Code] ....
If i do run the above program in turbo C/C++ complier, it outputs "h". But,if i change the code as i=0.6 and if (i<0.6), it outputs "w". Even if i change it to i=0.8 and if(i<0.8), then also it outputs "w".
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Dec 8, 2014
Trying to write 4 bytes ints in a binary file and extract them after... I'm using the exclusive or (^) to isolate single bytes to write to and extract from the file since the write() function accepts only chars, only the beginning and end results are not the same...
#include <iostream>
#include <ctime>
#include <fstream>
#include <cstdlib>
using namespace std;
[Code] .....
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May 29, 2013
I've been thinking over this for long time... For example, when a button is clicked, print a string "clicked" after 5 seconds. (the button won't be blocked)
Thread should be the only way to do this:
btn.on_click = []() {
thread thrd([]() { sleep_5_seconds(); cout << "clicked" << endl; });
thrd.start();
};
the local variable thrd is destructed right after it starts, which may cause a crash, so use new operator:
btn.on_click = []() {
thread* thrd = new thread([]() { sleep_5_seconds << "clicked" << endl; });
thrd->start();
};
The thrd never get deleted
How would you solve problem like this?
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Oct 7, 2014
int main()
{
char rORc, choice;
int sizerc;
[Code]....
when I input the character which is the underscore, and the row # it should display the table and sort that specific row. Why is the if statement skipped? This is not the complete program but has everything needed.
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Aug 25, 2013
I intend to reference this thread from another thread so I do not clutter that thread with code
/* This code is relied on by some of the functions I will post */
typedef unsigned long long zxumax;
typedef signed long long zxsmax;
[Code]....
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Feb 11, 2015
I'm working on a class project, and I'm having a difficulty. Suppose I have: string a = "21" and string b = "30"; normally, a+b=2130 (i.e concatenation of the characters in the string) but suppose I want a+b=51 (i.e. numerical addition) how do I go about this?
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Oct 27, 2012
How we can write coloured text to a text file in c? Can I use cprintf funtion with any kind editing
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Oct 30, 2014
I'm doing a bitwise operations on 2 bytes in a buffer, then storing the result in a variable. However, I sometimes get a non-zero value for the variable even though I'm expecting a zero value.
The relevant portion of the code is as follows.
unsigned int result = 0;
long j = 0, length;
unsigned char *data;
data = (unsigned char *)malloc(sizeof(unsigned char)*800000);
[Code] ......
I'm expecting result to be zero when my data[j] and data[j+1] are 0xb6 and 0xab respectively, which is the case for most of the time. However, for certain values of j, my result is strangely not zero.
j = 62910, result = 64
j = 78670, result = 64
j = 100594, result = 64
j = 165658, result = 512
j = 247990, result = 128
j = 268330, result = 512
j = 326754, result = 1
j = 415874, result = 256
j = 456654, result = 1024
j = 477366, result = 512
It appears that these strange result values are all powers of 2, with a 1 bit appearing somewhere in the unsigned int.
I'm not changing the value of result anywhere else in the code, and when I print out (unsigned int)(((data[j]^0xb6)<<8)|(data[j+1]^0xab)), I get 0, but somehow when it gets stored in result, it's no longer zero.
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Oct 24, 2013
Here's the code I'm writing:
Code:
#include <stdio.h>
#include <stdlib.h>
char* getTeamCode(char* team);
[Code]....
Why the placement of the code on line 21 above matters.
It grabs the correct string just fine. If I write a printf just below it, it prints the string it should correctly. However, if I do a printf of the string OSUteamCode below the fopen call on line 23, it prints blank.
So the first thing I did was move it below the fopen line. It worked, finding and outputting the first game in "game.csv" just fine, but not the other 11. Debugging with printf shows that the contents of OSUteamCode again disappear after the fopen call in the addLineCSV function.
I'm not understanding why that happens. The only thing I can figure is there's something going on with the file I/O commands that I just don't understand, but I can't find anything online that explains what that might be.
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Jan 9, 2015
I just started learning C++ a week ago and have been stuck on a project for the past 2 days now. I am building a limited purpose calculator which finds the value of one of five operations. Visual studio doesn't underline any errors in my program but every time I try to run it I get an error message. I believe it has something to do with the if/else but Im not sure.
#include <iostream>
using namespace std;
int main(){
int a;
int b;
int sum = a + b;
[Code] ....
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Jul 10, 2014
I've been assigned to build a program which completes mathematical operations using matrices. I have to use dynamically allocated 2d arrays, and can only use * to dereference and not []. I have this code so far, but the multiply_matrix function does not work with most values. I've looked at other similar posts, which have a similar algorithm to mine, but mine does not work for some reason.
/*
*(*matrix(matrix+i)+j)
*/
#include <iostream>
//for sleep() which allows user to see messages before screen is cleared
#include <unistd.h>
using namespace std;
[Code] .....
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Jul 13, 2013
how to use template parameters to perform arithmetic operations on objects.
I feel that it would best to demonstrate my issue rather than try and explain it.
Sample:
// Fundamental object structure
template<int T> struct myInt
{
myInt() { value = T; };
[Code]....
What I don't know is how to get a hold of the T variable to add them through the 'add' structure. Also, might any of this have to do with sequence wrappers?
seq_c<T,c1,c2,... cn> is essentially what I'm thinking of. Where T in this case is the type and c to the nth c are the values.
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Apr 21, 2013
I am trying to write a program to perform point operations on a elliptic curve in a prime field I am using the standard formulaes for point additions and doubling in my code and these operations are performed by functions that are called but I am getting output for certain points but not all.
Code:
structure point_multiply(int x, int y, int k ) {
int xk;
int yk,m;
xk=x;
yk=y;
m=1;
int xL,yL,s,e;
[code].....
s1, s2, s3 etc are structures which hold a 2 integers which act as x and y co-ordinates.I am getting output by entering k=3,g=4, h=5 and many other cases mostly with small numbers but not for larger numbers.
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