C language MCQ
June 13, 2012Memory Efficient doubly linked list
June 13, 2012Find error in the C++ code
What is the Error (if any) in the below C++ code
class TestClass
{
public:
// Constructors
TestClass():x(0) { }
TestClass(int a):x(a) { }
void printValue()
{
std::cout<< "Value :"<<x;
}
private:
int x;
};
int main()
{
TestClass obj();
obj.printValue();
}
Solution:
If we want to define an object of a class which uses default constructor then the object need to be defined as below
TestClass obj; // and NOT obj()
We are creating object in our code as
TestClass obj();
This is not creating an object, but declaring a function(prototype) obj whose return type is TestClass.
This is the problem, Since obj is not the object of class TestClass, calling function printValue using obj will give error. Hence the statement
obj.printValue();
Is an Error, but the reason is the attempt to create object in the previous statement.
When you want to create object of a class which uses 1 argument constructor (also called type-convertor constructor), the object is defined in one of the two ways:
TestClass obj(2); // Like a function call
TestClass obj = 2;
9 Comments
find error in this program
#include
#include
Using namespace Std;
int main();
{
int number;
for(i=1; i<=6, i++)
{
cout<<"Value of variable i is: "<<number<<endl;
getch();
}
#include
#include
class over
{
public:
void area(int);
void volume(int);
void area(int,int);
void volume(int,int,int);
};
void over::area(int a)
{
Int ar;
ar=a*a;
cout<<ar;
}
void over::volume(int a)
{
Int vol;
vol=a*a*a;
cout<<vol;
}
void over::area(int l,int b)
{
Int ar;
ar=l*b;
cout<<ar;
}
void over::volume(int l,int b,int h)
{
Int vol;
vol=l*b*h;
cout<<vol;
}
void main()
{
over f;
int a,l,b,h;
clrscr();
cout<>a;
cout<>l>>b>>h;
cout<<endl<<"area of square" ;
f.area(a);
cout<<endl<<"volume of square";
f.volume(a);
cout<<endl<<"area of rectangle";
f.area(l,b);
cout<<endl<<"volume of rectangle";
f.volume(l,b,h);
getch();
}
find error in this program plz
Arduino code:
#define Relay 13
#define buzzer A0
static const int sensorPin = 10; // sensor input pin
int SensorStatePrevious = LOW; // previousstate of the sensor
unsigned long minSensorDuration = 3000; // Time we wait before the sensor active as long
unsigned long minSensorDuration2 = 6000;
unsigned long SensorLongMillis; // Time in ms when the sensor was active
bool SensorStateLongTime = false; // True if it is a long active
const int intervalSensor = 50; // Time between two readings sensor state
unsigned long previousSensorMillis; // Timestamp of the latest reading
unsigned long SensorOutDuration; // Time the sensor is active in ms
//// GENERAL ////
unsigned long currentMillis; // Variabele to store the number of milleseconds since the Arduino has started
void setup() {
Serial.begin(9600); // Initialise the serial monitor
pinMode(sensorPin, INPUT); // set sensorPin as input
Serial.println(“Press button”);
pinMode(Relay,OUTPUT);
pinMode(buzzer,OUTPUT);
}
// Function for reading the sensor state
void readSensorState() {
// If the difference in time between the previous reading is larger than intervalsensor
if(currentMillis – previousSensorMillis > intervalSensor) {
// Read the digital value of the sensor (LOW/HIGH)
int SensorState = digitalRead(sensorPin);
// If the button has been active AND
// If the sensor wasn’t activated before AND
// IF there was not already a measurement running to determine how long the sensor has been activated
if (SensorState == LOW && SensorStatePrevious == HIGH && !SensorStateLongTime) {
SensorLongMillis = currentMillis;
SensorStatePrevious = LOW;
Serial.println(“Button pressed”);
}
// Calculate how long the sensor has been activated
SensorOutDuration = currentMillis – SensorLongMillis;
// If the button is active AND
// If there is no measurement running to determine how long the sensor is active AND
// If the time the sensor has been activated is larger or equal to the time needed for a long active
if (SensorState == LOW && !SensorStateLongTime && SensorOutDuration >= minSensorDuration) {
SensorStateLongTime = true;
digitalWrite(Relay,HIGH);
Serial.println(“Button long pressed”);
}
if (SensorState == LOW && SensorStateLongTime && SensorOutDuration >= minSensorDuration2) {
SensorStateLongTime = true;
digitalWrite(buzzer,HIGH);
delay(1000);
Serial.println(“Button long pressed”);
}
// If the sensor is released AND
// If the sensor was activated before
if (SensorState == HIGH && SensorStatePrevious == LOW) {
SensorStatePrevious = HIGH;
SensorStateLongTime = false;
digitalWrite(Relay,LOW);
digitalWrite(buzzer,LOW);
Serial.println(“Button released”);
}
// store the current timestamp in previousSensorMillis
previousSensorMillis = currentMillis;
}
}
void loop() {
currentMillis = millis(); // store the current time
readSensorState(); // read the sensor state
}
find errors :
#include
void main()
{ int public=10;
cout<public;
}
variable i type i,e int
#include<iostream
Using namespace Std;
int main(){
int number;
for (int i=0;i<=6;i++)
{
cout<<"Value of the variable is :"<<number;
return 0;
}
#include
#include
using namespace std;
int main() {
int number;
for (int i = 1; i <= 6; i++) {
cout << "Value of variable i is: " << i << endl;
}
return 0;
}
#include
using namespace std;
int main()
{
cout <> num;
copy= num;
while (num>0)
{
r= num%10;
rev= rev*10+r;
num= num/10;
}
if(copy==rev)
cout<<"the number is palindrome"
else
cout<<"the number is not palindrome"
return 0;
}
# include
Using namespace std;
main()
{
int a,b;
cin>>a>>b;
if(a=b)
cout<<”a is equal to b”;
cout<<”endl”;
if else (a!=b)
Cout<<”a is not equal to b”<<endl;
}