Control flow statements in C

Control Flow Statements are also C program statement. Which are used to specify the order in which my program get executed at run time. To control the order of program we use control flow statement.

Why we use control flow statements?

Our program execute in sequential order. But we want control the sequence of the program then we use control flow statement. We cannot write the large program using sequential programming. We only achieve it with the help of Conditional programming.

Two type programming order we use in C.

• Sequential Programming
• Conditional Programming

1. Sequential Programming

Only simple program we write in sequence order. It is not enough for large programming.

Example of simple Sequential programming:

	
    //Abstraction program
    void main()
    {
    int a = 10, b = 20, c;
    c = a + b;
    printf("Result is:- %d",c);
    
    getch();
    }
    

Conditional Programming

We cannot write the large program using Sequential programming. We only achieve it with the help of conditional along with Sequential programming.

Example of Conditional programming:

	
    //Greater number program
    void main()
    {
    int a = 2, b = 5;
    
    	if(a>b)
    	{
        printf("A is Greater.");
        }
        else
        {
        printf("B is Greater.");
        }
        
     getch()   
    }
    

In C we have three type of control flow statement.

Table of Control Flow Statements

Conditional Statement

if statement also called simple if statement.

Syntax of if condition:

	
    if(condition)
    {
    statement 1;
    }
    

Example of simple if conditional program using even-odd program.

	
    void main()
    {
    int num;
    printf("Enter the any number = ");
    scanf("%d",&num);
    if(num%2==0)
    {
    pritf("Number is even.");
    }
    getch();
    }
    

In above example you will see the even-odd number program which is without else condition.

Nested if condition

Nested if condition mean if condition within the if condition. You can write many nested if condition it's up to you.

Syntax of nested if condition:

    if(expression1)
    {
    	if(expression2)
        {
        statement1;
        }
        statement2;
    }

Working of nested if condition

If first if condition is false than it will simply come out from the all if condition. If first if condition is true than it will go to second if condition. If second if condition is also true than it will print the statement1 and statement2. If first if condition is true and second if condition is false than it will only print the statement2.

Example of nested if condition if both condition is true.

    void main()
    {
    clrscr();
    	if(2<5)
        {
            if(4<8)
            {
            printf("Ture\n");
            }
            printf("True");
        }
        getch();
    }
	

Output:

    True
    True
	

Example of nested if condition if both condition is false.

    void main()
    {
    clrscr();
    	if(2>5)
        {
        	if(4>8)
            {
            printf("Ture\n");
            }
            printf("True");
        }
        printf("It will print nothing because both condition is false.");
        getch();
    }
	

Output:

	
    It will print nothing because both condition is false.
    

if else condition

In if else condition executes the body of if when it is true and executes the body of else if (if) condition is false.

Example of if else condition if it is true:

    int num=5;
    if(num < 8)
	{
    printf("True");
    }
    else
    {
    printf("False");
    }
	

Output:

	True
    

Example of if else condition if it is false:

    int num = 5;
    if(num > 8)
	{
    printf("True");
    }
    else
    {
    printf("False");
    }
	

Output:

	False
    

Nested if else

Nested if else are used when there are more than one or more condition expression.

Syntax of nested if else

    if(expression)
    {
    statement1;
    }
    else if(expression2)
    {
    statement2
    }
    else if(expression3)
    {
    statement3
    }
    

Example of nested if else program

    void main()
    {
	int a=4,b=2,c=7;
	clrscr();
	if(a > b && a > c)
	{
	printf("a is greater.");
	}
	else if(b > a && b > c)
	{
	printf("b is greater.");
	}
	else
	{
	printf("c is greater");
	}
    getch();
}

Output:

    c is greater.