What's
a Loop?
A loop is used in C to allow
for a repeat of an action.
The loop starts the action, performs it then
returns to the start, then unless there is a
condition to tell the computer otherwise the
loop will run infinitely.
Why have a Loop?
A loop replaces the need
to type over and over again a operation that
you require the program to perform more than
once. It also allows the programmer to control
how many times the operation occurs using conditions.
What Are the Different
Types of Loop?
The first one is a
do while loop. This means the program will perform
the operation
as long as the condition(s) are true. The second one
is a while loop. This checks
if the condition is true at the start of the
operation. The loop will be performed
until this condition is found to be false.
Example of a Loop
-
You want to print out
the numbers 1 to 50
-
You will need a integer
called numbers
-
To perform this you need
to have a conditional loop.
-
Once you have printed
out The number 50 the loop needs to finish.
-
Therefore there must
be a condition whereby If the number is
greater than 50 the loop stops.
Program in C
#include <stdio.h> needed
to get access to C's standard input output library
int main() start of execution
of program
{ start of operations
int numbers; initialize
the integer numbers
numbers = 1; declare numbers
starts at 1 as you want the first number to
be printed out to be 1
while (numbers<51) The
condition Do only while the integer numbers
is less than 50
{printf("%i \n", numbers); print
out the integer numbers
numbers++; add one to
numbers integer
}
return 0; end program
return no error code
}
The For Loop
The for loop allows the program
to condense the loop into one line of code.
Program in C
#include <stdio.h>
int main()
{
int index;
for (index=0; index<51; index) this
is the loop section while the integer index
is less than 50 - then carry on & do the
loop below
{
printf("%i\n", index++); the
operation the loop is to perform in this case
print out the value of integer index then add
1 to it
}
return 0;
}
Advantages of a For
Loop
one - the programmer has
less to write
two - the computer has less
code to read so its slightly faster
three - its easier to add
more loops
Conclusion
The for loop saves the programmer
time - if he/she wanted to create the above
program without using the loop function they
would have to type out the routine 50 times.
It also allows the programmer a great degree
of control over both how many times the operation
is performed along with the ability to add many
different types of conditions that effect the
loop. |
