There may be a situation, when you need to
execute a block of code several number of times. In general, statements are
executed sequentially: The first statement in a function is executed first,
followed by the second, and so on.
Programming languages provide various control
structures that allow for more complicated execution paths.
A loop statement allows us to execute a
statement or group of statements multiple times and following is the general
form of a loop statement in most of the programming languages:
while loop in C
A while loop statement in C programming language repeatedly executes
a target statement as long as a given condition is true.
Syntax:
The syntax of a while loop
in C programming language is:
while(condition)
{
statement(s);
}
Here, statement(s) may be a single statement or a block
of statements. The condition may be any expression, and true is
any nonzero value. The loop iterates while the condition is true.
When the condition becomes false, program control passes to
the line immediately following the loop.
Flow Diagram:
Here, key point of the while loop
is that the loop might not ever run. When the condition is tested and the
result is false, the loop body will be skipped and the first statement after
the while loop will be executed.
Example:
#include <stdio.h>
int main ()
{
/* local variable
definition */
int a = 10;
/* while loop execution
*/
while( a < 20 )
{
printf("value
of a: %d\n", a);
a++;
}
return 0;
}
When the above code is compiled and executed, it produces
the following result:
value of a: 10
value of a: 11
value of a: 12
value of a: 13
value of a: 14
value of a: 15
value of a: 16
value of a: 17
value of a: 18
value of a: 19
do...while loop in C
Unlike for and while loops, which test the loop condition at the top of the loop,
thedo...while loop in C programming language checks its condition at the
bottom of the loop.
A do...while loop is similar to a while loop,
except that a do...while loop is guaranteed to execute at least one time.
Syntax:
The syntax of a do...while loop
in C programming language is:
do
{
statement(s);
}while( condition );
Notice that the conditional expression appears at the end of
the loop, so the statement(s) in the loop execute once before the condition is
tested.
If the condition is true, the flow of control jumps back up
to do, and the statement(s) in the loop execute again. This process repeats
until the given condition becomes false.
Flow Diagram:
Example:
#include <stdio.h>
int main ()
{
/* local variable
definition */
int a = 10;
/* do loop execution */
do
{
printf("value
of a: %d\n", a);
a = a + 1;
}while( a < 20 );
return 0;
}
When the above code is compiled and executed, it produces
the following result:
value of a: 10
value of a: 11
value of a: 12
value of a: 13
value of a: 14
value of a: 15
value of a: 16
value of a: 17
value of a: 18
value of a: 19
for loop in C
A for loop is a repetition control structure that allows you to
efficiently write a loop that needs to execute a specific number of times.
Syntax:
The syntax of a for loop
in C programming language is:
for ( init; condition; increment )
{
statement(s);
}
Here is the flow of control in a for loop:
1.
The init step
is executed first, and only once. This step allows you to declare and
initialize any loop control variables. You are not required to put a statement
here, as long as a semicolon appears.
2.
Next, the condition is evaluated. If it is true, the
body of the loop is executed. If it is false, the body of the loop does not
execute and flow of control jumps to the next statement just after the for
loop.
3.
After the body of the for loop
executes, the flow of control jumps back up to theincrement statement.
This statement allows you to update any loop control variables. This statement
can be left blank, as long as a semicolon appears after the condition.
4.
The condition is now evaluated
again. If it is true, the loop executes and the process repeats itself (body of
loop, then increment step, and then again condition). After the condition
becomes false, the for loop terminates.
Flow Diagram:
Example:
#include <stdio.h>
int main ()
{
/* for loop execution
*/
for( int a = 10; a <
20; a = a + 1 )
{
printf("value
of a: %d\n", a);
}
return 0;
}
When the above code is compiled and executed, it produces
the following result:
value of a: 10
value of a: 11
value of a: 12
value of a: 13
value of a: 14
value of a: 15
value of a: 16
value of a: 17
value of a: 18
value of a: 19
|Footer Menu |
| Introduction | Basic Syntax | Data Types | Variables | Arrays | Constants and Literals |
| Decision Making | Functions | L values and R values | Loops | Nested if statements | Nested loops |
| Nested Switch Statements | Operators | Pointers | Scope Rules |
| Strings | Storage Classes | Structures | Switch Statement |
|Footer Menu |
| Introduction | Basic Syntax | Data Types | Variables | Arrays | Constants and Literals |
| Decision Making | Functions | L values and R values | Loops | Nested if statements | Nested loops |
| Nested Switch Statements | Operators | Pointers | Scope Rules |
| Strings | Storage Classes | Structures | Switch Statement |
No comments:
Post a Comment