Thanks for reading my problem. My loop code is not working as expected. The console output must not display negative numbers but it still does display them.
While (x > 0 && Y > 0)
{
--x;
--y;
cout << x << endl;
cout << y << endl;
}
I'm still a beginner in c++.
'Y' and 'y' are different. Perhaps you want to write it this way:
while (x > 0 && y > 0)
{
// First print the value and then decrement it
cout << x << endl;
cout << y << endl;
--x;
--y;
}
Related
I am trying to use a while loop to calculate the average of 3 inputted grades, but I can not enter the next grade as the loops keep on going without giving me the chance to enter the next grade.
#include<iostream>
using namespace std;
int main()
{
int grade = 0;
int count = 0;
int total = 0;
cout << "Enter grade: ";
cin >> grade;
while (grade != -1)
{
total = total + grade;
count = count + 1;
cout << "Enter next grade: ";
cin >> grade;
}
int(average) = total / 3;
cout << "Average: " << int(average) << endl;
system("pause");
}
I tested your code with integer and it works fine.
If you only take int as input, the best is to put something to check the input type. Use cin.fail() to check if user input anything other than int.
for example:
while(cin.fail()) {
cout << "Error" << endl;
cin.clear();
cin.ignore(256,'\n');
cout << "Please enter grade:"
std::cin >> grade;
}
which I refer from https://www.codegrepper.com/code-examples/cpp/how+to+check+type+of+input+cin+c%2B%2B
and here as well Checking cin input stream produces an integer
I have this problem using Visual Studio 2017:
int x = 2, y = -3;
cout << ((--x + y && y++ - x) || x-- + (--y + x++)) << endl;
cout << "x = " << x << ", y = " << y << endl << endl;
It always shows that the result of the whole statement is 1 (which is OK) and that x = 1 and y = -2.
What I don't understand is how can y by equal to -2? In my calculation it should be -3!
I referenced to this link: https://msdn.microsoft.com/en-us/library/126fe14k.aspx
The right-hand side of the || operator is not performed because the left-hand side expression && operator evaluates to true.
So only y++ has taken place, leaving it as -2.
I'm not an expert but here are my views:
cout << ((--x + y && y++ - x) || x-- + (--y + x++)) << endl;
((--x + y && y++ - x) resolves to -4 which is non zero and hence is true. So x-- + (--y + x++)) don't have to be checked and no need to execute that code.
in the expression (--x + y && y++ - x) there is a --x so that will result in a decrement in x and y++ will result in an increment in y, ie. y=-3+1.
In this Book object I created a system to keep track of the time a book has been checked out... there is a tm* called dateCheckedOut to store the date that the book is checked out.
int Book::getHeldTime()
{
time_t now ;
time(&now);
tm* t = localtime(&now);
double difference = difftime(now, mktime(dateCheckedOut))/(60 * 60 * 24);
cout << dateCheckedOut->tm_mon << dateCheckedOut->tm_mday << dateCheckedOut->tm_year << endl; //prints out 231117, which is correct.
cout << t->tm_mon << t->tm_mday << t->tm_year << endl; //prints out 34117, which is also correct
cout << difftime(now, mktime(dateCheckedOut)) << endl; //prints out 0
cout << difference << endl; //prints out 0;
return (int)(difference); //returns 0
}
I am quite confused because I checked the date when its checked out and the date when it is loaded, both are correct, but the difftime function just returns 0. Is there anything that might cause this code to not work? Thank in advance!
P.S. dateCheckedOut only has tm_mday, tm_mon, and tm_year set to the correct value, the rest are all not set. Is that a problem?
I was trying to make use of the new Shape Transformers and Interfaces of OpenCV3.0. Unfortunately it doesn't work as expected. To ensure not making any fancy warps and getting strange results cause of that reason I initialized a transformation where nothing at all should happen. But output of the transformation for a testpoint is always [0,0] and the warped image is always completley gray. Any suggestions what could be wrong are welcome.
int main(void){
Mat img1 = imread("C:\\opencv\\sources\\samples\\data\\graf1.png", IMREAD_GRAYSCALE);
std::vector<cv::Point2f> points1, testpoints;
vector<DMatch> good_matches;
Mat respic, resmat;
points1.push_back(Point(0, 0)); //Corners 800x600 pic
points1.push_back(Point(799, 0));
points1.push_back(Point(799, 599));
points1.push_back(Point(0, 599));
Mat pointmatrix1(points1);
good_matches.push_back(DMatch(0, 0, 0));
good_matches.push_back(DMatch(1, 1, 0));
good_matches.push_back(DMatch(2, 2, 0));
good_matches.push_back(DMatch(3, 3, 0));
testpoints.push_back(Point(250, 250));
Mat testpointsmat(testpoints);
// Apply TPS
Ptr<ThinPlateSplineShapeTransformer> mytps = createThinPlateSplineShapeTransformer(0);
mytps->estimateTransformation(pointmatrix1, pointmatrix1, good_matches); // Using same pointmatrix nothing should change in res
mytps->applyTransformation(testpointsmat, resmat);
cout << "pointmatrix1 = " << endl << " " << pointmatrix1 << endl << endl;
cout << "testpointsmat = " << endl << " " << testpointsmat << endl << endl;
cout << "resmat = " << endl << " " << resmat << endl << endl; //Always [0,0] ?
imshow("img1", img1); // Just to see if I have a good picture
mytps->warpImage(img1, respic);
imwrite("Tranformed.png", respic);
imshow("Tranformed", respic); //Always completley grey ?
waitKey(0);
return 0;
}
Don't ask me why but if I add this two lines it works.
// Apply TPS
transpose(pointmatrix1, pointmatrix1); // ADD
transpose(testpoints, testpoints); // ADD
Ptr<ThinPlateSplineShapeTransformer> mytps = createThinPlateSplineShapeTransformer(0);
Now There is something strange in source code here why cols and not rows.
by LBerger
I'm working on a mini-compiler and I reached the code generation level.
I want to store a string dynamically to the heap segment, so I wrote this C++ code (cg is the file I'm generating assembly code to) :
int length = strlen("abc");
cg << "\tori\t$a0,$0," << (length + 3) * 4 << endl; // reserve space for type + length + null + size
cg << "\tori\t$v0,$0,9" << endl;
cg << "\tsyscall" << endl;
increamentSP();
cg << "\tsw\t$v0,0($sp)" << endl;
cg << "\tori\t$t1,$0,1" << endl; // store the type
cg << "\tsw\t$t1,0($v0)" << endl;
cg << "\tori\t$t1,$0," << length << endl; // store the length
cg << "\tsw\t$t1," << 4 << "($v0)" << endl;
for (int i = 0; i < length; i++)
{
cg << "\tori\t$t1,$0," << (int)p->val[i] << endl; // store the char
cg << "\tsw\t$t1," << (2 + i) * 4 << "($v0)" << endl;
}
cg << "\tsw\t$0," << (2 + length) * 4 << "($v0)" << endl;
Basically, what I'm trying to do is :
First, I want to store a flag (1) referring that this type is a string to the first location.
Then, I want to store the size of my string to the second location.
After that, I want to store my strings chars to the next locations.
Finally, I want to store a null-terminating char to the last location.
My problem is that when I try to print my string using a code like this :
la $a0,8($t0)
ori $v0,$0,4
syscall
The result is that mips prints only the letter 'a', how can I print a string stored like this? or is there any better way to store my string?
p.s. I know I can use .asciiz in the .data segment, but the problem is that in my code I might edit the string, so I don't exactly know what my string would become.
Can any one help me with that?