Loops (b)
In This Section:
Increment and Decrement, The For Statement, Simple For Loops
A for loop repeats a function for a specific number of times.
Increment and decrement
For loops use increment and decrement operators.
- increment means to loop again, counting up (1, 2, 3, 4, ...) The symbol for increment is ++
- decrement means to loop again, counting down (... 4, 3, 2, 1) The symbol for decrement is --
Let's study increment first. When you increment something, you add 1 to it. For example, if loop = 1, then ++loop = 2. If I increment again, then ++loop = 3.
NOTE: In simple for loops, we can write the increment before or after the variable: ++loop or loop++. In other expressions, however, these two are quite different.)
The for statement
To write a for loop, we must use the for statment, which contains three parts:
- initialize the counter: set the counter to begin at 1 (or any other number)
- set how many times you want it to loop
- increment the loop
Here is a sample for statement with these three parts:
for(loop = 1; loop < 4; ++loop)
This statement says, "Starting at 1, if the loop is less than 4, then loop again." This means that you will loop 3 times, because when you reach 4, the loop will stop.
NOTE: You can use any variable in a for statement, instead of "loop". Some programmers use "count" or "input".
Simple for loop
Let's write a simple for loop that repeats "Have a great day!" three times on the screen.
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#include<stdio.h>
void main( )
{
int loop;
for(loop = 1; loop < 4; ++loop)
printf("\nHave a great day!");
}
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Type this source code in your editor and save it as floop.c then compile it, link it, and run it.
Now let's write a for loop that repeats "Have you paid those parking tickets yet?" six times on the screen:
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#include<stdio.h>
void main( )
{
int count;
for(count = 1; count < 7; ++count)
printf("\nHave you paid those parking tickets yet?");
}
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Notice that we have changed three things: the name of the variable (count), the number of times to repeat the loop count < 7; and the question.
Type this source code in your editor and save it as parking.c then compile it, link it, and run it.
