How to run C++ program on your computer
To run any programming language on your local machine or computer you need a compiler first. The compiler reads each and every line of your program. It interprets line by line actually. If there is no error in the program, they only go ahead to run your particular program. In our case, we are using the "DEV C++" compiler to run our programs. You can easily download and install the "DEV C++ application file" or .exe file from the internet.
How to save C++ files on your computer
You simply go to your "DEV C++" and then click on "new" in the file section in the upper tabs. Then save the file adding the ".cpp" extension. For example, if your program name is "myfirstprogram" then save it as "myfirstprogram. cpp".
Hello World program in C++
#include <iostream>
using namespace std; // it calls the library
int main() { // it defines the method main()
cout << "Hello World!"; // 'cout' is used for printing
return 0; // it returns only one value
}
Result
Hello World!
In the above program, "using namespace std;" calls a library that has a set of signs that are used to identify and refer to objects of various kinds. Here in the 3rd line main() is a method.
How To Add Comments in C++ Programming
To add comments in C++ Programming you need to write "//", then write your comment.
For Example
#include <iostream>
using namespace std;
int main() {
int x = 22; //declaring of variable x
if (x >= 10) {
cout << "It is true";
}
else {
cout << "It is false";
}
/*
It is a comment on multiple lines
If...else is used for adding conditions in C programming
*/
return 0;
}
Here, in the above code single line comment is written after "//". But if comments contain multiple lines then we use "/* Your Comment of multiple lines */" as shown in the above code.
Declaring of Variable in C++
In all programming languages, we declare some variable for specific purposes.
#include <iostream>
using namespace std;
int main() {
int x = 5;
int y = 10;
int sum = x + y;
cout << "Value of x + y = " << sum;
}
Result
Value of x + y = 15
Here in the above code, we've declared two variables x = 5, and y=10.
'Else If' Condition in C++ Programming
#include <iostream>
using namespace std;
int main() {
int product;
cout << "Enter the number of product: ";
cin >> product;
if (product < 500) {
cout << "Total price = " << product*20;
} else if (product >= 500 && product < 1000) {
cout << "Total price = " << product*18;
} else {
cout << "Total price = " << product*15;
}
return 0;
}
Result
Enter the number of products: 400
Total price = 8000
We implemented three different conditions for an e-commerce application for the wholesale market in the code above. If you buy less than 500 items, you'll have to pay $20 for each one. If you buy more than 500 but fewer than 1000 units, you pay 18 dollars for each unit. The third condition is that if you purchase more than 1000 items, you will be charged $15 for each item.
While For - Loop in C++ Programming
We often need to run a loop inside a program to run several iterations and impose many logics, conditions, etc.
Example
In a school sport, a group of three pupils will compete in a three-round running race. After each round, you must record the time taken by each student. Calculate the average time taken by each student over the three rounds once they have completed all of the rounds, and choose the student with the lowest average timing as the best runner. If more than one student meets the minimum average timing criteria, they must all be chosen. Show the fastest runner's name and average timing.
Solution in C++
Inputs:
The time taken by three students over three rounds to complete a 100-meter run is as follows
Student A: 8, 9, 9 (in second)
Student B: 9, 8, 12 (in second)
Student C: 7, 11, 9 (in second)
Condition:
All students will be judged unfit if they fail to maintain an average timing of 12 seconds over the three rounds, or if the time average taken by all students is greater than 12 seconds.
The input of the code is below:
8
9
7
9
8
11
9
12
9
Code:
#include <iostream>
#include <cmath>
using namespace std;
int main() {
int x, T1=0, T2=0, T3=0, count=1;
double A1, A2, A3;
while (count <=9)
{
cin >> x;
if(count%3==1)
T1=T1+x;
else if(count%3==2)
T2=T2+x;
else
T3=T3+x;
count++;
}
A1= (T1/3);
A2= (T2/3);
A3= (T3/3);
if(A1>=12 && A2>=12 && A3>=12) {
cout<<"All trainees are unfit";
return 0;
}
if(A1<=A2 && A1<=A3){
cout<<"Student A"<<endl;
}
if(A2<=A1 && A2<=A3){
cout<<"Student B"<<endl;
}
if(A3<=A1 && A3<=A2){
cout<<"Student C"<<endl;
}
return 0;
}
Result:
Student A
We can say Student A takes less average time to cover 3 rounds of 100 meters runs.
Solve the following C Programs
#include<stdio.h>
int main() {
int a=2,b=2;
a=b<<a;
printf("%d", a);
return 0;
}
Output: 8
Explanation:
Operator "<<" denotes the left shifting of bits and operator ">>" denotes the right shifting of bits.
So, here operation occurs in bit level
b = 2 = binary 10; If we shift bits in the left direction by 2 places then it will be 1000 which is equal to decimal 8
So, the output will be 8 in the above code.