//Java Program to count the total number of characters in a string
import java.util.*;
public class CountChars
{
public static void main(String args[])
{
Scanner in=new Scanner(System.in);
String s; int i;
System.out.println("Enter a String");
s=in.nextLine();
for(i=0;i<s.length();i++)
if(s.charAt(i)=='\0')
break;
System.out.println("The String "+s+" has "+i+" characters");
}
}
Output:
//Java Program to count the total number of characters in a string
import java.util.*;
public class CountChars
{
public static void main(String args[])
{
Scanner in=new Scanner(System.in);
String s; int i;
System.out.println("Enter a String");
s=in.nextLine();
for(i=0;i<s.length();i++)
if(s.charAt(i)=='\0')
break;
System.out.println("The String "+s+" has "+i+" characters");
}
}
You have already learned that cout is used to output (print) values. Now we will use cin to get user input.
cin is a predefined variable that reads data from the keyboard with the extraction operator (>>).
In the following example, the user can input a number, which is stored in the variable x. Then we print the value of x:
int x;
cout << "Type a number: "; // Type a number and press enter
cin >> x; // Get user input from the keyboard
cout << "Your number is: " << x; // Display the input valuecout is pronounced "see-out". Used for output, and uses the insertion operator (<<)
cin is pronounced "see-in". Used for input, and uses the extraction operator (>>)
In this example, the user must input two numbers. Then we print the sum by calculating (adding) the two numbers:
int x, y;
int sum;
cout << "Type a number: ";
cin >> x;
cout << "Type another number: ";
cin >> y;
sum = x + y;
cout << "Sum is: " << sum;Variables are containers for storing data values.
In C++, there are different types of variables (defined with different keywords), for example:
int - stores integers (whole numbers), without decimals, such as 123 or -123double - stores floating point numbers, with decimals, such as 19.99 or -19.99char - stores single characters, such as 'a' or 'B'. Char values are surrounded by single quotesstring - stores text, such as "Hello World". String values are surrounded by double quotesbool - stores values with two states: true or falseTo create a variable, you must specify the type and assign it a value:
type variable = value;Where type is one of C++ types (such as int), and variable is the name of the variable (such as x or myName). The equal sign is used to assign values to the variable.
To create a variable that should store a number, look at the following example:
Create a variable called myNum of type int and assign it the value 15:
int myNum = 15;
cout << myNum;You can also declare a variable without assigning the value, and assign the value later:
int myNum;
myNum = 15;
cout << myNum;Note that if you assign a new value to an existing variable, it will overwrite the previous value:
int myNum = 15; // myNum is 15
myNum = 10; // Now myNum is 10
cout << myNum; // Outputs 10A demonstration of other data types:
int myNum = 5; // Integer (whole number without decimals)
double myFloatNum = 5.99; // Floating point number (with decimals)
char myLetter = 'D'; // Character
string myText = "Hello"; // String (text)
bool myBoolean = true; // Boolean (true or false)The cout object is used together with the << operator to display variables.
To combine both text and a variable, separate them with the << operator:
int myAge = 35;
cout << "I am " << myAge << " years old.";To add a variable to another variable, you can use the + operator:
int x = 5;
int y = 6;
int sum = x + y;
cout << sum;To declare more than one variable of the same type, use a comma-separated list:
int x = 5, y = 6, z = 50;
cout << x + y + z;C++ Identifiers
All C++ variables must be identified with unique names.
These unique names are called identifiers.
Identifiers can be short names (like x and y) or more descriptive names (age, sum, totalVolume).
Note: It is recommended to use descriptive names in order to create understandable and maintainable code:
Example
// Good
int minutesPerHour = 60;
// OK, but not so easy to understand what m actually is
int m = 60;
The general rules for constructing names for variables (unique identifiers) are:
- Names can contain letters, digits and underscores
- Names must begin with a letter or an underscore (_)
- Names are case sensitive (
myVar and myvar are different variables) - Names cannot contain whitespaces or special characters like !, #, %, etc.
- Reserved words (like C++ keywords, such as
int) cannot be used as names.
When you do not want others (or yourself) to override existing variable values, use the const keyword (this will declare the variable as "constant", which means unchangeable and read-only):
Example
const int myNum = 15; // myNum will always be 15
myNum = 10; // error: assignment of read-only variable 'myNum'
You should always declare the variable as constant when you have values that are unlikely to change:
Example
const int minutesPerHour = 60;
const float PI = 3.14;Comments can be used to explain C++ code, and to make it more readable. It can also be used to prevent execution when testing alternative code. Comments can be singled-lined or multi-lined.
Single-line comments start with two forward slashes (//).
Any text between // and the end of the line is ignored by the compiler (will not be executed).
This example uses a single-line comment before a line of code:
// This is a comment
cout << "Hello World!";This example uses a single-line comment at the end of a line of code:
cout << "Hello World!"; // This is a commentMulti-line comments start with /* and ends with */.
Any text between /* and */ will be ignored by the compiler:
/* The code below will print the words Hello World!
to the screen, and it is amazing */
cout << "Hello World!";It is up to you which you want to use. Normally, we use // for short comments, and /* */ for longer.
The cout object, together with the << (Stream insertion) operator, is used to output values/print text:
#include <iostream>
using namespace std;
int main() {
cout << "Hello World!";
return 0;
}cout objects as you want. However, note that it does not insert a new line at the end of the output:#include <iostream>
using namespace std;
int main() {
cout << "Hello World!";
cout << "I am learning C++";
return 0;
}C++ New LinesTo insert a new line, you can use the \n character (escape sequence) :
Example
#include <iostream>
using namespace std;
int main() {
cout << "Hello World! \n";
cout << "I am learning C++";
return 0;
}Tip: Two \n characters after each other will create a blank lineExample
#include <iostream>
using namespace std;
int main() {
cout << "Hello World! \n\n";
cout << "I am learning C++";
return 0;
}Another way to insert a new line, is with the endl manipulator:
Example
#include <iostream>
using namespace std;
int main() {
cout << "Hello World!" << endl;
cout << "I am learning C++";
return 0;
}Both \n and endl are used to break lines. However, \n is used more often and is the preferred way.Let's break up the following code to understand it better:
#include <iostream>
using namespace std;
int main() {
cout << "Hello World!";
return 0;
}Line 1: #include <iostream> is a header file library that lets us work with input and output objects, such as cout (used in line 5). Header files add functionality to C++ programs.
Line 2: using namespace std means that we can use names for objects and variables from the standard library.
Don't worry if you don't understand how #include <iostream> and using namespace std works. Just think of it as something that (almost) always appears in your program.
Line 3: A blank line. C++ ignores white space.
Line 4: Another thing that always appear in a C++ program, is int main(). This is called a function. Any code inside its curly brackets {} will be executed.
Line 5: cout (pronounced "see-out") is an object used together with the insertion operator (<<) to output/print text. In our example it will output "Hello World".
Note: Every C++ statement ends with a semicolon ;.
Note: The body of int main() could also been written as:int main () { cout << "Hello World! "; return 0; }
Remember: The compiler ignores white spaces. However, multiple lines makes the code more readable.
Line 6: return 0 ends the main function.
Line 7: Do not forget to add the closing curly bracket } to actually end the main function.
You might see some C++ programs that runs without the standard namespace library. The using namespace std line can be omitted and replaced with the std keyword, followed by the :: operator for some objects:
#include <iostream>
int main() {
std::cout << "Hello World!";
return 0;
}It is up to you if you want to include the standard namespace library or not.
In programming languages, loops are used to execute a set of instructions/functions repeatedly when some conditions become true. There are three types of loops in Java.
| Comparison | for loop | while loop | do while loop |
|---|---|---|---|
| Introduction | The Java for loop is a control flow statement that iterates a part of the programs multiple times. | The Java while loop is a control flow statement that executes a part of the programs repeatedly on the basis of given boolean condition. | The Java do while loop is a control flow statement that executes a part of the programs at least once and the further execution depends upon the given boolean condition. |
| When to use | If the number of iteration is fixed, it is recommended to use for loop. | If the number of iteration is not fixed, it is recommended to use while loop. | If the number of iteration is not fixed and you must have to execute the loop at least once, it is recommended to use the do-while loop. |
| Syntax | for(init;condition;incr/decr){
// code to be executed
}
| while(condition){
//code to be executed
}
| do{
//code to be executed
}while(condition);
|
| Example | //for loop
for(int i=1;i<=10;i++){
System.out.println(i);
}
| //while loop
int i=1;
while(i<=10){
System.out.println(i);
i++;
}
| //do-while loop
int i=1;
do{
System.out.println(i);
i++;
}while(i<=10);
|
| Syntax for infinitive loop | for(;;){
//code to be executed
}
| while(true){
//code to be executed
}
| do{
//code to be executed
}while(true); |
//To find the sum of two compatible matrices
#include<iostream>
using namespace std;
main()
{
int r1,c1,r2,c2,i,j,sum[50][50];
cout<<"Enter the order of the first matrix\n";
cin>>r1>>c1;
int arr1[r1][c1];
cout<<"Enter the elements of the first matrix\n";
for(i=0;i<r1;i++)
{
for(j=0;j<c1;j++)
cin>>arr1[i][j];
}
cout<<"Enter the order of the second matrix\n";
cin>>r2>>c2;
int arr2[r2][c2];
cout<<"Enter the elements of the second matrix\n";
for(i=0;i<r2;i++)
{
for(j=0;j<c2;j++)
cin>>arr2[i][j];
}
if(r1==r2&&c1==c2)
{
for(i=0;i<r1;i++)
{
for(j=0;j<c1;j++)
sum[i][j]=arr1[i][j]+arr2[i][j];
}
cout<<"The resultant matrix is:\n";
for(i=0;i<r1;i++)
{
for(j=0;j<c1;j++)
cout<<sum[i][j]<<" ";
cout<<"\n";
}
}
else
cout<<"Matrices are not compatible …";
}
#include<iostream>
using namespace std;
class Factorial
{
public:
int f=1,n,i;
void Fact()
{
cout<<"Enter a Number\n";
cin>>n;
for(i=1;i<=n;i++)
f*=i;
cout<<"Factorial of "<<n<<" is "<<f;
}
};
main()
{
Factorial obj;
obj.Fact();
}
#include<iostream>
using namespace std;
class Sum
{
public:
int a,b,c;
void input()
{
cout<<"Enter 2 Numbers\n";
cin>>a>>b;
}
void Calculate()
{
c=a+b;
}
void Display()
{
cout<<"Sum = "<<c;
}
};
main()
{
Sum obj;
obj.input();
obj.Calculate();
obj. Display();
}
#include<iostream>
using namespace std;
main()
{
int SUM(int,int);
int a=10,b=20,sum;
sum=SUM(a,b);
cout<<"Sum of 2 numbers = "<<sum;
}
int SUM(int x,int y)
{
return(x+y);
}
//WAP TO ADD 2 MATRICES
#include<iostream>
using namespace std;
main()
{
int i,j,n;
cout<<"Enter the Size of the Matrix"<<endl;
cin>>n;
int a[n][n],b[n][n],c[n][n];
cout<<"Enter the elements of the Matrix a"<<endl;
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
cin>>a[i][j];
}
cout<<"Enter the elements of the Matrix b"<<endl;
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
cin>>b[i][j];
}
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
c[i][j]=a[i][j]+b[i][j];
}
cout<<"The Sum of the Two Matrices:"<<endl;
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
cout<<c[i][j]<<" ";
cout<<endl;
}
}
import java.util.*;
class DDA
{
public static void main(String args[])
{
Scanner in=new Scanner(System.in);
int i,j,n;
System.out.println("Enter the Size of the Matrix");
n=in.nextInt();
int a[][]=new int[n][n];
System.out.println("Enter the elements of the Matrix");
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
a[i][j]=in.nextInt();
}
System.out.println("The Martix:");
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
System.out.print(a[i][j]+" ");
System.out.println();
}
}
}
//WAP IN C++ TO ADD 2 MATRICES
#include<iostream>
using namespace std;
main()
{
int a[10][10],i,j,n;
cout<<"Enter the Size of the Matrix";
cin>>n;
cout<<"Enter the elements of the Matrix"<<endl;
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
cin>>a[i][j];
}
cout<<"The Martix:"<<endl;
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
{
cout<<a[i][j]<<" ";
}
cout<<endl;
}
}
import java.util.*;
class Sum_Array
{
public static void main(String args[])
{
Scanner in=new Scanner(System.in);
int N,i,sum=0;
System.out.println("Enter the size of the array");
N=in.nextInt();
int arr[]=new int[N];
System.out.println("Enter "+N+" Numbers");
for(i=0;i<N;i++)
{
arr[i]=in.nextInt();
sum=sum+arr[i];
}
System.out.println("The Sum of the elements of the array is: "+sum);
}
}
//Program to find product of 2 matrices
#include<iostream>
using namespace std;
main()
{
int A[10][10],B[10][10],C[10][10],i,j,k,n;
cout<<"Enter the size of the Matrix\n";
cin>>n;
cout<<"Enter the elements of Matrix A\n";
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
cin>>A[i][j];
}
cout<<"Enter the elements of Matrix B\n";
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
cin>>B[i][j];
}
for(i=0;i<n;i++)
for(j=0;j<n;j++)
{
C[i][j]=0;
for(k=0;k<n;k++)
C[i][j]=C[i][j]+A[i][k]*B[k][j];
}
cout<<"The product of the 2 matrices :\n";
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
cout<<C[i][j]<<" ";
cout<<endl;
}
}
#include <iostream>
using namespace std;
main()
{
int N,i;
cout<<"Enter the size of the array\n";
cin>>N;
int arr[N];
cout<<"Enter "<<N<<" Numbers\n";
for(i=0;i<N;i++)
cin>>arr[i];
cout<<"The elements of the array are:\n";
for(i=0;i<N;i++)
cout<<arr[i]<<"\n";
}
import java.util.*;
public class Main
{
public static void main(String args[])
{
Scanner in=new Scanner(System.in);
int N,i;
System.out.println("Enter the size of the array");
N=in.nextInt();
int arr[]=new int[N];
System.out.println("Enter "+N+" Numbers");
for(i=0;i<N;i++)
arr[i]=in.nextInt();
System.out.println("The elements of the array are:");
for(i=0;i<N;i++)
System.out.println(arr[i]);
}
}
#include <iostream>
using namespace std;
main()
{
int N,i,sum=0;
cout<<"Enter the size of the array\n";
cin>>N;
int arr[N];
cout<<"Enter "<<N<<" Numbers\n";
for(i=0;i<N;i++)
{
cin>>arr[i];
sum=sum+arr[i];
}
cout<<"The Sum of the elements of the array is: "<<sum;
}
import java.util.*;
public class Main
{
public static void main(String args[])
{
Scanner in=new Scanner(System.in);
char ch;
System.out.println("Enter a Character to check whether it is a vowel or a Constant");
ch=in.next().charAt(0);
if(ch=='a'||ch=='e'||ch=='i'||ch=='o'||ch=='u')
System.out.println(ch+" is a Vowel.");
else
System.out.println(ch+" is a Constant.");
}
}
//C++ Program to accept a letter and check Whether a character is Vowel or Consonant.
#include<iostream>
using namespace std;
main()
{
char ch;
cout<<"Enter a Character to check whether it is a vowel or a Constant\n";
cin>>ch;
if(ch=='a'||ch=='e'||ch=='i'||ch=='o'||ch=='u')
cout<<ch<<" is a Vowel.";
else
cout<<ch<<" is a Constant.";
}
//Write a Program in C++ to find Sum of 2 Numbers using assignment statement.
#include<iostream>
using namespace std;
main()
{
int a=10,b=20,sum;
sum=a+b;
cout<<"Sum= "<<sum;
}
public class Sum
{
public static void main(String args[])
{
int a=10,b=20,sum;
sum=a+b;
System.out.println("Sum= "+sum);
}
}
#include<iostream>
#include<cmath>
using namespace std;
main()
{
int a,b,c,Min;
cout<<"Enter 3 Numbers\n";
cin>>a>>b>>c;
Min=min(a,b);
Min=min(Min,c);
cout<<"Smallest Number= "<<Min;
}
import java.util.*;
class Min
{
public static void main(String args[])
{
Scanner in=new Scanner(System.in);
int a,b,c,min;
System.out.println("Enter 3 Numbers");
a=in.nextInt();
b=in.nextInt();
c=in.nextInt();
min=Math.min(a,b);
min=Math.min(min,c);
System.out.println("Smallest Number= "+min);
}
}
#include<iostream>
#include<cmath>
using namespace std;
main()
{
double a,d;
cout<<"Enter the side of the Square\n";
cin>>a;
d=sqrt(2)*a;
cout<<"Side of the Square= "<<a<<"\n";
cout<<"Diagonal of the Square= "<<d<<"\n";
}
import java.util.*;
class Diagonal
{
public static void main(String args[])
{
Scanner in=new Scanner(System.in);
double a,d;
System.out.println("Enter the side of the Square");
a=in.nextInt();
d=Math.sqrt(2)*a;
System.out.println("Side of the Square= "+a);
System.out.println("Diagonal of the Square= "+d);
}
}
/* Question: The final velocity of a vehicle can be calculated by using the formula:
V2=u2+2as;
where u= initial velocity, a=acceleration, s=distance covered
Write a Program in C++ to calculate and Display the final velocity by taking initial velocity, acceleration and the distance covered as inputs. */
#include<iostream>
#include<cmath>
using namespace std;
main()
{
int u,a,s;
double v;
cout<<"Enter the initial Velocity, acceleration and distance covered\n";
cin>>u>>a>>s;
v=sqrt((u*u)+(2*a*s));
cout<<"Final Velocity = "<<v;
}
//Java Program to count the total number of characters in a string import java.util.*; public class CountChars { public static void mai...
