The lesson will show you how to:
Q. How do you make a blonde laugh on a Saturday?
A. Tell her a joke on a Wednesday
Iteration, for loops
The basic format of the for statement
is:
for (start condition; continue condition; re-evaluation)
program statement;
/* Sample program using a for statement
*/
#include <stdio.h>
int main(void)
{
int count;
for (count = 1; count <=10; count = count + 1)
printf(“%d”, count);
printf(”\n”);
return 0;
}
Sample program output
1 2 3 4 5 6 7 8 9 10
The program declares an integer variable count. The first
part of the for statement
for (count = 1
Initializes the value of count to 1. The for loop continues
whilst the condition
count <=10
Evaluates to TRUE. A s the variable count has just been
initialized to 1, this condition is TRUE and so the program
statement
printf(“%d”, count
);
Is executed, which prints the value of count to the screen,
followed by a space character. Next, the remaining statement
of the for is executed
count = count + 1)
Which adds one to the current value of count. Control now
passes back to the conditional test,
count <= 10
Which evaluates as TRUE, so the program statement
printf(“%d”, count);
Is executed. Count is incremented again, the condition re-evaluated
etc, until count reaches a value of 11. When this occurs
the conditional test
count <= 10
Evaluates as FALSE, and the for loop terminates, and program
control passes to the statement
printf(“\n”);
Which prints a new line, and then the program terminates,
as there are no more statements left to execute.
// sample program using a for statement
#include <stdio.h>
int main(void)
{
int n, t_number;
t_number = 0;
for (n = 1; n <= 200; n = n + 1)
t_number = t_number + n;
printf(“The 200th triangular_number is %d\n”,
t_number);
return 0;
}
Sample program output
The 200th triangular_number is 20100
The above program uses a for loop to calculate the sum
of the numbers from 1 to 200 inclusive (said to be the triangular
number).
An example of using a for loop to print out characters
#include <stdio.h>
int main(void)
{
char letter;
for (letter = ‘A’; letter <= ‘E’;
letter = letter + 1)
{
printf(“%c”, letter);
}
return 0;
}
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