Lab Fri 2/15 - Sample solution

Problem a, b, and c are from Wed's class. Make SURE you 
understand the answer. If not, ask a TA.  Once you
are solid on a,b,c - start on question d.

a) int count = 0; // initialization
while( count < 5 ) {  // condition
   System.out.println(count);  // body
   count++;   // same as count = count + 1;  update
}
count 0,1,2,3,4,5
Output
0
1
2
3
4

b) int count = 0;
while( count < 5 ) {
   count++;
   System.out.print(count + " ");
}
count 0,1,2,3,4,5
Output
1 2 3 4 5


c) int count = 0;
while( count < 5 ) {
   System.out.println(count);
}

infinite loop


What is the output from the following code segments?


d) int count = 0;
do {
   System.out.println(count);
   count++;
} while( count < 0 );
System.out.println( "count after loop = " + count);

0
count after loop = 1


e) int count = 0;
while( count < 0 ) {
   System.out.println(count);
   count++;
} 
System.out.println( "count after loop = " + count);

count after loop = 0

f) 
String str = "aabcaddjoabla";
int count = 0;
int index = 0;
while( index < str.length() ) {
   if( 'a' == str.charAt(index)) {
      count++;
   }
   index++;
}
System.out.println(count);

5
This program count the number of times the letter 'a'
appears in the string.

g) What is wrong with the following code segment?
String str = "aabcaddjoabla";
int count = 0;
int index = 0;
while( index < str.length() ) {
   if( 'a' == str.charAt(index)) {
      count++;
   }
   else index++;
}
System.out.println(count);

When the character 'a' is seen, the loop update
(index++) is not performed. Compare to part f above.