C++ Programming Code Examples
C++ > If Else and Switch Case Code Examples
If we write an entire if-else construct within either the body of the if statement or the body of an else statement.
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/* If we write an entire if-else construct within either the body of the if statement or the body of an else statement.
This is called "nesting" of ifs. This is demonstrated as - */
if (expression1)
statement;
else
{
if (expression2)
statement;
else
{
block of statement;
}
}
Structures in C++ Language
In C++, classes and structs are blueprints that are used to create the instance of a class. Structs are used for lightweight objects such as Rectangle, color, Point, etc. Unlike class, structs in C++ are value type than reference type. It is useful if you have data that is not intended to be modified after creation of struct.
C++ Structure is a collection of different data types. It is similar to the class that holds different types of data.
Syntax for Structures in C++
struct structureName{
member1;
member2;
member3;
.
.
.
memberN;
};
struct Teacher
{
char name[20];
int id;
int age;
}
s.id = 4;
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/* Structure is a collection of variables of different data types under a single name. It is similar to a class in that, both holds a collecion of data of different data types. */
#include <iostream>
using namespace std;
struct Person
{
char name[50];
int age;
float salary;
};
int main()
{
Person p1;
cout << "Enter Full name: ";
cin.get(p1.name, 50);
cout << "Enter age: ";
cin >> p1.age;
cout << "Enter salary: ";
cin >> p1.salary;
cout << "\nDisplaying Information." << endl;
cout << "Name: " << p1.name << endl;
cout <<"Age: " << p1.age << endl;
cout << "Salary: " << p1.salary;
return 0;
}
If Else Statement in C++
In computer programming, we use the if statement to run a block code only when a certain condition is met. An if statement can be followed by an optional else statement, which executes when the boolean expression is false. There are three forms of if...else statements in C++:
• if statement,
• if...else statement,
• if...else if...else statement,
Syntax for If Statement in C++
if (condition) {
// body of if statement
}
Syntax for If...Else Statement
if (condition) {
// block of code if condition is true
}
else {
// block of code if condition is false
}
Syntax for If...Else...Else If Statement in C++
if (condition1) {
// code block 1
}
else if (condition2){
// code block 2
}
else {
// code block 3
}
Syntax for If Else If Ladder in C++
if (condition)
statement 1;
else if (condition)
statement 2;
.
.
else
statement;
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/* If Else Statement in C++ Language */
#include <iostream>
using namespace std;
int main () {
// local variable declaration:
int a = 100;
// check the boolean condition
if( a < 20 ) {
// if condition is true then print the following
cout << "a is less than 20;" << endl;
} else {
// if condition is false then print the following
cout << "a is not less than 20;" << endl;
}
cout << "value of a is : " << a << endl;
return 0;
}
If Else If Ladder in C/C++
The if...else statement executes two different codes depending upon whether the test expression is true or false. Sometimes, a choice has to be made from more than 2 possibilities. The if...else ladder allows you to check between multiple test expressions and execute different statements.
In C/C++ if-else-if ladder helps user decide from among multiple options. The C/C++ if statements are executed from the top down. As soon as one of the conditions controlling the if is true, the statement associated with that if is executed, and the rest of the C else-if ladder is bypassed. If none of the conditions is true, then the final else statement will be executed.
Syntax of if...else Ladder in C++
if (Condition1)
{ Statement1; }
else if(Condition2)
{ Statement2; }
.
.
.
else if(ConditionN)
{ StatementN; }
else
{ Default_Statement; }
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/* write a C program which demonstrate use of if-else-if ladder statement */
/* Program to Print Day Names using Else If Ladder in C++*/
#include <iostream>
using namespace std;
int main()
{
int day;
cout << "Enter Day Number: ";
cin >> day;
cout << "Day is ";
if (day == 1)
cout << "Sunday" << endl;
else if (day == 2)
cout << "Monday" << endl;
else if (day == 3)
cout << "Tuesday" << endl;
else if (day == 4)
cout << "Wednesday" << endl;
else if (day == 5)
cout << "Thursday" << endl;
else if (day == 6)
cout << "Friday" << endl;
else
cout << "Saturday" << endl;
return 0;
}
Relational Operators in C++
A relational operator is used to check the relationship between two operands. C++ Relational Operators are used to relate or compare given operands. Relational operations are like checking if two operands are equal or not equal, greater or lesser, etc.
Relational Operators are also called Comparison Operators.
• == Is Equal To 4 == 9 gives us false
• != Not Equal To 4 != 9 gives us true
• > Greater Than 4 > 9 gives us false
• < Less Than 4 < 9 gives us true
• >= Greater Than or Equal To 4 >= 9 give us false
• <= Less Than or Equal To 4 <= 9 gives us true
==
Equal To Operator (==) is used to compare both operands and returns 1 if both are equal or the same, and 0 represents the operands that are not equal.
The equal to == operator returns
true - if both the operands are equal or the same
false - if the operands are unequal
int x = 10;
int y = 15;
int z = 10;
x == y // false
x == z // true
The relational operator == is not the same as the assignment operator =. The assignment operator = assigns a value to a variable, constant, array, or vector. It does not compare two operands.
!=
Not Equal To Operator (!=) is the opposite of the Equal To Operator and is represented as the (!=) operator. The Not Equal To Operator compares two operands and returns 1 if both operands are not the same; otherwise, it returns 0.
The not equal to != operator returns
true - if both operands are unequal
false - if both operands are equal.
int x = 10;
int y = 15;
int z = 10;
x != y // true
x != z // false
>
Greater than Operator (>) checks the value of the left operand is greater than the right operand, and if the statement is true, the operator is said to be the Greater Than Operator.
The greater than > operator returns
true - if the left operand is greater than the right
false - if the left operand is less than the right
int x = 10;
int y = 15;
x > y // false
y > x // true
<
Less than Operator (<) is used to check whether the value of the left operand is less than the right operand, and if the statement is true, the operator is known as the Less than Operator.
The less than operator < returns
true - if the left operand is less than the right
false - if the left operand is greater than right
int x = 10;
int y = 15;
x < y // true
y < x // false
>=
Greater than Equal To Operator (>=) checks whether the left operand's value is greater than or equal to the right operand. If the statement is true, the operator is said to be the Greater than Equal to Operator.
The greater than or equal to >= operator returns
true - if the left operand is either greater than or equal to the right
false - if the left operand is less than the right
int x = 10;
int y = 15;
int z = 10;
x >= y // false
y >= x // true
z >= x // true
<=
Less than Equal To Operator (<=) checks whether the value of the left operand is less than or equal to the right operand, and if the statement is true, the operator is said to be the Less than Equal To Operator.
The less than or equal to operator <= returns
true - if the left operand is either less than or equal to the right
false - if the left operand is greater than right
int x = 10;
int y = 15;
x > y // false
y > x // true
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/* Relational Operators are used for the comparison of the values of two operands. For example, checking if one operand is equal to the other operand or not, an operand is greater than the other operand or not, etc. Some of the relational operators are (==, >= , <= ). */
#include <iostream>
using namespace std;
main() {
int a = 21;
int b = 10;
int c ;
if( a == b ) {
cout << "Line 1 - a is equal to b" << endl ;
} else {
cout << "Line 1 - a is not equal to b" << endl ;
}
if( a < b ) {
cout << "Line 2 - a is less than b" << endl ;
} else {
cout << "Line 2 - a is not less than b" << endl ;
}
if( a > b ) {
cout << "Line 3 - a is greater than b" << endl ;
} else {
cout << "Line 3 - a is not greater than b" << endl ;
}
/* Let's change the values of a and b */
a = 5;
b = 20;
if( a <= b ) {
cout << "Line 4 - a is either less than \ or equal to b" << endl ;
}
if( b >= a ) {
cout << "Line 5 - b is either greater than \ or equal to b" << endl ;
}
return 0;
}
Comments in C++
The C++ comments are statements that are not executed by the compiler. The comments in C++ programming can be used to provide explanation of the code, variable, method or class. If we write comments on our code, it will be easier for us to understand the code in the future. Also, it will be easier for your fellow developers to understand the code. By the help of comments, you can hide the program code also. There are two types of comments in C++:
• Single Line comment
• Multi Line comment
Syntax for Single Line Comment in C++
/* This is a comment */
Syntax for Multi Line Comment in C++
/* C++ comments can also
* span multiple lines
*/
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/* program to illustrate use comments in C++ language */
#include <ostream>
using namespace std;
int main()
{
int x = 11; // x is a variable
cout<<x<<"\n";
/* declare and
print variable in C++ */
int x = 35;
cout<<x<<"\n";
// This is a comment
cout << "Hello World!";
/* Multi-line Comments
in C++ */
}
Use the three variable say a, b and c. Place b in a and c in b then place a+b in c to print the value of c to make and print Fibonacci series as shown here in the following C++ program.
The Edmonds_Karp Algorithm which is used to compute the maximum flow between the 'sink and source vertex'. It is the same as the "Ford - Fulkersson" Algorithm except that it
This represents the queue dequeue function. Every time another object or customer enters the line to wait, they join the "end of the line" and represent the "enqueue function". Queue