While executing this code i was getting a error Invalid lvalue in assignment. Can any one tell how to correct this.
dataItem* d=(dataItam*)malloc(10*sizeof(dataItem));
dataItem* temp;
temp=(d+6);
(d+6)=(d+8);//error line
(d+8)=temp;//error line
The issue arises with case 3 where it tells produces an error when I attempt to compile and says "lvalue required for left operand of assignment error". How to fix this so that I can properly run the program.
View 5 Replies View RelatedI get the following error:
pointers_array.c: In function ‘readlines’:
pointers_array.c:42:37: error: lvalue required as left operand of assignment
I know what the error is saying but what it is giving it with this code:
/* readlines: read input lines */
int readlines(char *lineptr[], int maxlines) {
int len, nlines;
char *p, line[MAXLEN];
nlines = 0;
[Code] ....
I got above error in my program. My program is socket program. I am using ubuntu 11.10.
#include <netdb.h>
#include <netinet/in.h>
#include <string.h>
#include <cstdlib>
#include <iostream>
#include <stdio.h>
#define PORT 4547
/*int parseARGS(char **args, char *line) {
[Code] ....
i want to modify value of whole array by passing it to a function and make each value of array multiplied by 3 ,return the value to main and print it using pointer.
error : invalid Lvalue is the error
Code:
#include<stdio.h>
main()
{
int i,arr[10];
for (i=0;i<=9;i++)
{
printf("Enter value of arr[%d] : ",i);
scanf("%d",&arr[i]);
[Code] ....
I have the following code. According to this the values of pointers p[0] and p[1] remains unchanged since the swap is made to local variables in swap function.Now my doubt is how can I swap the pointers p[0] and p[1] inside the function swap??
Code:
#include<stdio.h>int main(){char*p[2]={"hello","good morning"};
swap(p[0],p[1]);
printf("%s %s",p[0],p[1]);return0;
}void swap(char*a,char*b){char*t; t=a; a=b; b=t;
}
I am using OpenCV to read and manipulate a set of images, which I need to store in an array to work with them. Here is a snippet of the code:
#define MAX_IMAGES 8
typedef Mat* MatPtr;
int main(int argc, char** argv) {
char imageName[] = "./res/imageX.tiff";
MatPtr datacube[MAX_IMAGES];
[code].....
I have an array of pointers to Mat objects (an OpenCV class used to hold info and data about an image), which I will use to store the images. The function imread reads an image and returns a Mat object loaded with the relevant data about the image.However, this gives me a nice segfault when the assignment takes place. Of course, I can swap it with the following code, but since I'm working with big images (2048x2048 and upwards), it's really inefficient:
for(unsigned int i = 0; i < MAX_IMAGES; i++) {
imageName[11] = 49 + i;
datacube[i] = new Mat(imread(imageName, -1));
}
Is there any way to do this elegantly and without much hassle?Again, excuse my rustiness and anything completely stupid I might have said. It's been a long time since I worked with C++. Managed to circumvent the problem by using a STD vector instead of an array. I'd still like to know the answer to this riddle...
why are the arithmetic operations like division(p/q) and multiplication(p*q) invalid on pointers?.here p and q both are pointers .
View 6 Replies View Relatedwrite a swap function to swap 2 elements in the vector?
View 3 Replies View RelatedI actually am wanting to practice on a 2 dimension char array. so, I am using the below program and getting the error - Lvalue Required For Function Main
#include <stdio.h>
#include <conio.h>
#include <string.h>
char varStringArray[1][5];
int main(void) {
clrscr();
varStringArray[0] = 'a';
printf("%c", varStringArray[0]);
return 0;
}
Trying to understand the lvalue and rvalue references, and come up with some strange codes, which compile and run, but is confusing to understand.
Define this class Thing:
class Thing {
public:
Thing(int k = 0): i(k) {};
~Thing() { std::cout << "destroying Thing (i=" << i << ")" << std::endl; }
int getValue() const { return i; };
Thing &getMe() { return *this; };
private:
int i;
};
and a non-member function:
Thing construct_Thing10() {
Thing t(10);
return t;
}
Then these two lines in main():
Thing &thg=construct_Thing10().getMe();
std::cout << "member=" << thg.getValue() << std::endl;
The output is:
destroying Thing (i=10)
member=10
My understanding is that the rhs of line 1 construct only a temporary object. getMe() then return the reference of this temp object and bind it to thg (as a lvalue reference). After line one, the temp object is really destroyed (hence the first output line). At this point thg is really binding to a destroyed, invalid object. But somehow the 2nd line still prints the correct value of 10 is because the memory storage is not yet corrupted (still holding the previous value). Is this correct?
I have the following code segment:
Code:
void Swap(Number& num1, Number& num2)
{
cout<<"Before swap:"<<num1<<" "<<num2<<endl;
Number& temp=num1;
num1=num2;
num2=temp;
cout<<"After swap:"<<num1<<" "<<num2<<endl;
}
[code]...
to which the output is:
Code:
Before swap:13 11
After swap:13 11
13 11 that seems confusing.
why doesn't Swap() swap the two Numbers?
#include <iostream>
#include <conio.h>
using namespace std;
[Code]....
appears that error on line 25 & 30 where swap1 & swap2 is not declared in this scope.
This is for homework . Must use only getchar and putchar
Code:
int main(void) {
int pch; //first
int ch; //second
[Code]....
And it works , but i need to hit ENTER two times when i have 3,5,7... chars to print result.
how to swap the first and 'mid' elements of a vector?
View 2 Replies View RelatedThe idea is to make an array and have it sort the contents inside the array in order from smallest to greatest by using a swap function. I don't know why it needs to be done this way when a sort function makes the most sense, but it is what it is.
For simplicity I want my array to only include three numbers. I was thinking {18,-2,24}. My only problem is that I am not understanding how to translate the swap function in an array. I tried using my previous swap function from another assignment and translate it to work for an array, but it doesn't work and I am completely lost and stuck. What I tried to do was this:
#include <iostream>
#include <cstdlib>
using namespace std;
const int SIZE = 3;
double myList[3] = {18, -2, 24};
void swap(myList[0], myList[1], myList[2]) {
[Code] ....
I want to swap the value of two rows in matrix among themselves, the index of rows are user defined.
void swapRows(int matrix[M][N], int m, int n, unsigned short R1, unsigned short R2) {
for (int i=0; i<m; i++) {
for (int j=0; j<n; j++) {
//dunno what to put in here
[Code] .....
How to swap two strings without using 3rd variable? could it be done using constructors? If yes how?
View 11 Replies View RelatedIm trying to swap the values of an integer and a character, however Im not sure where to insert the static_cast<type> part that I need for this to happen?
// Program to demonstrate a function template
#include <iostream>
using namespace std;
// Interchanges the values of variable1 and variable2
template<class T>
void swap_values(T& variable1, T& variable2)
[Code] ....
writing a sorting function that has an argument for a vector of ints rather than an array; it should use a selection sort algorithm.Here is what I have:
#include <iostream>
#include <vector>
#include <conio.h>
using namespace std;
void fillVector(vector<int> &aVector);
// PRECONDITION: number declared size of array a.
// POSTCONDITION: number_used is the number of values stored in a
//a[0] through a[number_used-1] have been filled with nonnegative int.
[code].....
I simply need to know how I could swap the first and last letters of the input in this program:
int main() {
cout << "---------------------------------------------------------" << endl;
cout << " Letter Swapping Program" << endl;
cout << "---------------------------------------------------------" << endl;
string word;
cout << "Please enter a word at least 3 letters long: ";
cin >> word;
[Code] ....
By all means, I know this is a messy program and is not the most concise way to write it....
I'm using code blocks ....
1.Write a program to swap positions of digits of a user entered three-digit integer N, where N is equal or between 101 and 999. (i.e. if user enters 389 your program should print 983. If user enters 300 program should print 003). Repeatedly ask user for correct N, if he/she enters an integer N which is not in the range.
2. Given that y= 4*( 1- 1/3 + 1/5- 1/7+ 1/9-...plus or minus 1/N) Write a program using a for-loop or a while-loop to compute and print the sum of first 50 terms of y.
3. a) Write a user-defined function funGx to compute G(x), where
5 if x<-10
x^2 +(5/x) if -10 <=x<-5
x^2 - (5/x-5) if -5<=x<5
x^2 -(5/x) if 5<=x<10
-5 if x>=10
b) Call the user-defined function funGx in main function to compute and print G(x)values for x= -15.5 , x=5, and x= 0.5 in an informative sentence.
So I been working on this c++ project and I need to be able to take three seperate strings and send them to function to put them in alphabetical order through a-z and use the swap function to return them in order. I been searching for problems like this but I haven't fame across any. I can copy my code onto here as well as a more detailed description of what I'm needing to do onto here if needed.
View 4 Replies View RelatedI am trying to realize a simple code with thread and lambda function.
My goal is to swap 2 variable . I launch 2 thread,
The first:
Put his value in a shared variable and notify it .
wait until an event on a condition variable occur.
read from shared value .
The second wait until an event on a condition variable occur.
Wake up
read from shared value .
Put his value in a shared variable and notify it.
This is the code
thread t1([&p1]()->void{
m.lock();
nt++;
if(nt==1) {
//first thread
unique_lock<mutex> u1(m); ***
[Code] .....
Why it say error "abort() has been called " on the istr ***
I am reading a book currently on data structures in c++. The questions I have is how I would be able to swap two adjacent elements by adjusting only the links (not the data) using, a) singly linked lists, doubly linked lists.
For the single linked list which I am somewhat familiar with (by the content of the book), I would consider taking the Node A, and copying its data into a new Node temp, then re-routing the pointer from whatever connected to Node A, now to Node temp. now I want to re-route the pointer of Node B to Node temp and Node temp to whatever Node was being connected from Node B. Is this the correct approach?
I am having problems with my game of fifteen. I have implemented the swap> I know the swap takes place[using GDB] but the swap does not show on the screen even if GDB says it has taken place. I am getting no errors from the move function so I know that something is taking place. I was thinking that the problem may be in the draw function but it looks okay to me. I have looked at this over and over but I don't know why the draw is not printing the move to the screen.
#define _XOPEN_SOURCE 500
#include <cs50.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
// board's minimal dimension
#define MIN 3
// board's maximal dimension
#define MAX 9
[Code] ....