Page 55 - Programming Microcontrollers in C

40 Chapter 1 Introduction to C

desired to execute the statement at least once whether the argument is
TRUE or not. In such a case, the argument should be tested at the end
of the loop rather than at the beginning as with the while. The do/
while construct accomplishes this operation. The construction of a
do-while loop is as follows

.
.
do
{
.
.
.
} while (expression);
.

The program will enter the do construct and execute the code that
follows up to the while statement. At that time, the expression is
evaluated. If it is TRUE, program control is returned to the statement
following the do. Otherwise, if the expression evaluates to FALSE,
control will pass to the statement following the while. Notice that
there is a semicolon following the while(expression). This semi­
colon is necessary for correct operation of the do-while loop.
The following function converts the integer number n into the
corresponding ASCII string. The function has two parts: the first
part converts the number into an ASCII string, but the result is back­
ward in the array; the second part reverses the data in the array so
that the result is correct.

/* convert a positive integer to an ASCII string;
valid for positive numbers only */

void itoa(unsigned int n, char s[])
{
int i=0,j=0,temp;

/* convert the number to ASCII */

do
{