In programming there exists situations where you need to iterate single or a set of repetitive statement for a number of times.Such situations in C programming are handled using nested loops.C programming language supports nesting of one loop inside another.

Nested while loop

A while loop inside another while loop is called nested while loop.

Syntax of nested loop

outer_loop
{
    inner_loop
    {
        // Inner loop statement/s
    }

    // Outer loop statement/s
}

outer_loop and inner_loop is one of the valid C loop.

Syntax of Nested while loop

while (condition1)
{
    statement(s);
    while (condition2)
    {
        statement(s);
        ... ... ...
    }
    ... ... ...
}

Flowchart of Nested while loop

Nested do-while loop

A do-while loop inside another do-while loop is called nested do-while loop.

Syntax of Nested do-while loop

do
{
    statement(s);
    do
    {
        statement(s);
        ... ... ...
    }while (condition2);
    ... ... ...
}while (condition1);

Flowchart of Nested do-while loop

Nested for loop

A for loop inside another for loop is called nested for loop.

Syntax of Nested for loop

for (initialization; condition; increment/decrement)
{
    statement(s);
    for (initialization; condition; increment/decrement)
    {
        statement(s);
        ... ... ...
    }
    ... ... ...
}

Flowchart of Nested for loop