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2. do while Loops This slide show illustrates the order of execution of a do while loop. Christine S. Wolfe Ohio University Lancaster 2008-Aug-01 Vocabulary: do while *affect the condition (of the loop) initialization (of the loop) loop body loop repetition condition

3. In a do while loop: a set of instructions is executed at least once and is repeated as long as a condition is true.

4. body of the loop the test affect the test initialize the test } while (ThisVote != ‘Q’); { do ©Christine S. Wolfe printf(“Vote for your favorite of the following TV shows”); printf(“\n\nA – Lost”); printf(“\nB – The Office”); printf(“\nC – Dancing with the Stars”); printf("\nEnter your vote as A, B, or C: ”); fflush(stdin); scanf(“\n%c”, &ThisVote); printf(“Vote for your favorite of the following TV shows”); printf(“\n\nA – Lost”); printf(“\nB – The Office”); printf(“\nC – Dancing with the Stars”); printf("\nEnter your vote as A, B, or C: ”); fflush(stdin); scanf(“\n%c”, &ThisVote); switch(ThisVote) { case ‘A’: ++TotalVotesA; break; case ‘B’: ++TotalVotesB; break; case ‘C’: ++TotalVotesC; break; default: printf(“\n Invalid response: “); getchar(); } notice that the body is executed once BEFORE even reaching the test!

5. X = 1; { Y = X * 2; } x < 3 ++X; X = 1; { Y = X * 2; } ++X; do while ( ) x < 3 while ( ) ; while X = 1; { Y = X * 2; } ++X; x < 3 Like ALL loops, a do while loop can be written as a while loop. The opposite is NOT true. It is NOT true that all while loops can be rewritten as do while loops – at least not elegantly.

6. X = 1; { Y = X * 2; } X = 1; { Y = X * 2; } ++X; do while ( ) x < 3 while ( ) ; ++X; X < 3 XY 2 1 2 34 Ending Values X 3 Y 4 XY 2 1 2 34 Ending Values X 3 Y 4

7. INIT BLOCK includes while loop WHILE TEST AFFECT INIT BLOCK includes do while loop WHILE TEST AFFECT T F F T do